QGIS 2.0 UserGuide Id - PDFCOFFEE.COM (2024)

QGIS User Guide Rilis 2.0

QGIS Project

16 May 2014

Daftar Isi

1

Pendahuluan

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Konvensi 2.1 Konvensi GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Konvensi Teks atau Papan Ketik . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Petunjuk Spesifik Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Kata Pengantar

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Keistimewaan 4.1 Lihat data . . . . . . . . . . . . . . . . . . . . . . . 4.2 Jelajahi data dan menyusun peta . . . . . . . . . . . 4.3 Membuat, menyunting, mengelola dan ekspor data . 4.4 Analisis data . . . . . . . . . . . . . . . . . . . . . 4.5 Terbitkan peta di Internet . . . . . . . . . . . . . . . 4.6 Memperpanjang fungsionalitas QGIS melalui plugin 4.7 Python Console . . . . . . . . . . . . . . . . . . . .

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7 7 7 8 8 8 8 9

Apa yang baru pada QGIS 2.0 5.1 Antarmuka Pengguna . . 5.2 Penyedia Data . . . . . . 5.3 Simbologi . . . . . . . . 5.4 Penyusun Peta . . . . . . 5.5 Pelabelan . . . . . . . . . 5.6 Programmability . . . . . 5.7 Alat Analisis . . . . . . . 5.8 Plugin . . . . . . . . . . . 5.9 Umum . . . . . . . . . . 5.10 Legenda Pelapis (layer) . 5.11 Peramban . . . . . . . . .

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11 11 11 12 13 14 14 15 15 15 16 16

Memulai 6.1 Pemasangan (Instalasi) . . . . . . . 6.2 Contoh data . . . . . . . . . . . . . 6.3 Sesi Contoh . . . . . . . . . . . . . 6.4 Memulai dan Menghentikan QGIS 6.5 Pilihan Baris Perintah . . . . . . . 6.6 Proyek . . . . . . . . . . . . . . . 6.7 Keluaran (Output) . . . . . . . . .

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17 17 17 18 19 19 21 21

QGIS GUI 7.1 Bar Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Toolbar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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7.3 7.4 7.5 8

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Legenda Peta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tampilan Peta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Status Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Peralatan Umum 8.1 Fitur Identifikasi . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 Shortcut Papanketik . . . . . . . . . . . . . . . . . . . . . . . 8.3 Konteks Bantuan . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 Rendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 Mengukur . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6 Dekorasi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7 Peralatan Anotasi . . . . . . . . . . . . . . . . . . . . . . . . . 8.8 Bookmark Spasial . . . . . . . . . . . . . . . . . . . . . . . . 8.9 Proyek-proyek Nesting . . . . . . . . . . . . . . . . . . . . . . 8.10 Menambahkan Lapisan Teks Delimited (Delimited Text Layer)

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35 35 36 37 37 38 40 42 43 44 45

Konfigurasi QGIS 9.1 Panel dan Toolbar . . . . . . 9.2 Properti Proyek . . . . . . . . 9.3 Opsi . . . . . . . . . . . . . . 9.4 Penyesuaian (Customization)

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47 47 48 48 55

10 Working with Projections 10.1 Overview of Projection Support . . . . 10.2 Global Projection Specification . . . . 10.3 Define On The Fly (OTF) Reprojection 10.4 Custom Coordinate Reference System .

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57 57 57 58 59

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11 QGIS Peramban 12 Pekerjaan dengan Data Vektor 12.1 Supported Data Formats . . . 12.2 The Vector Properties Dialog 12.3 Editing . . . . . . . . . . . . 12.4 Query Builder . . . . . . . . 12.5 Field Calculator . . . . . . .

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13 Pekerjaan dengan Data Raster 113 13.1 Working with Raster Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 13.2 Raster Properties Dialog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 13.3 Raster Calculator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 14 Pekerjaan dengan Data OGC 121 14.1 QGIS as OGC Data Client . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 14.2 QGIS as OGC Data Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 15 Pekerjaan dengan Data GPS 133 15.1 GPS Plugin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 15.2 Live GPS tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 16 GRASS GIS Integration 16.1 Starting the GRASS plugin . . . . . . . . . 16.2 Loading GRASS raster and vector layers . . 16.3 GRASS LOCATION and MAPSET . . . . . 16.4 Importing data into a GRASS LOCATION . 16.5 The GRASS vector data model . . . . . . . 16.6 Creating a new GRASS vector layer . . . . . 16.7 Digitizing and editing a GRASS vector layer 16.8 The GRASS region tool . . . . . . . . . . . 16.9 The GRASS toolbox . . . . . . . . . . . . . ii

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139 139 140 140 143 143 144 144 147 147

17 QGIS kerangka pengolahan 17.1 Pengantar . . . . . . . . . . . . . . . . . . . . 17.2 The toolbox . . . . . . . . . . . . . . . . . . . 17.3 The graphical modeler . . . . . . . . . . . . . 17.4 The batch processing interface . . . . . . . . . 17.5 Using processing algorithms from the console 17.6 The history manager . . . . . . . . . . . . . . 17.7 Configuring external applications . . . . . . . 17.8 The SEXTANTE Commander . . . . . . . . .

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157 157 159 166 172 174 179 180 186

18 Print Composer 18.1 First steps . . . . . . . 18.2 Rendering mode . . . 18.3 Composer Items . . . 18.4 Item alignment . . . . 18.5 Atlas generation . . . 18.6 Creating Output . . . 18.7 Manage the Composer

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189 190 192 193 206 207 209 210

19 Plugin 19.1 Plugin QGIS . . . . . . . . . . . . . . . . 19.2 Menggunakan QGIS Plugin Inti . . . . . . 19.3 Plugin Mengambil Koordinat . . . . . . . 19.4 Plugin Pengelola DB . . . . . . . . . . . . 19.5 Plugin Pengonversi Dxf2Shp . . . . . . . . 19.6 eVis Plugin . . . . . . . . . . . . . . . . . 19.7 Plugin fTools . . . . . . . . . . . . . . . . 19.8 Plugin Alat GDAL . . . . . . . . . . . . . 19.9 Plugin Georeferencer . . . . . . . . . . . . 19.10 Plugin Interpolasi . . . . . . . . . . . . . . 19.11 Plugin Mengedit Diluar Jaringan (Offline) . 19.12 Oracle GeoRaster Plugin . . . . . . . . . . 19.13 Plugin Raster Analisis Terrain . . . . . . . 19.14 Heatmap Plugin . . . . . . . . . . . . . . 19.15 Plugin Grafik Jalan . . . . . . . . . . . . . 19.16 Plugin Spasial Query . . . . . . . . . . . . 19.17 Plugin SQL Anywhere . . . . . . . . . . . 19.18 Topology Checker Plugin . . . . . . . . . 19.19 Plugin Statistik Zonal . . . . . . . . . . .

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211 211 214 214 215 216 217 226 229 232 235 236 237 239 240 243 244 245 246 248

20 Bantuan dan Dukungan 20.1 Milis . . . . . . . 20.2 IRC . . . . . . . . 20.3 BugTracker . . . . 20.4 Blog . . . . . . . 20.5 Plugin . . . . . . . 20.6 Wiki . . . . . . .

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21 Appendix 253 21.1 GNU General Public License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 21.2 GNU Free Documentation License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 22 Literatur dan Referensi Web

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Indeks

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iv

BAB 1

Pendahuluan

Dokumen ini merupakan buku petunjuk asli dari perangkat lunak yang dijelaskan QGIS. Perangkat lunak dan perangkat keras yang dijelaskan dalam dokumen ini dalam banyak kasus merupakan merek dagang terdaftar dan karena itu tunduk pada persyaratan hukum. QGIS menggunakan Lisensi Publik Umum GNU (GNU General Public License). Temukan informasi lebih lanjut pada QGIS alamat web http://www.qgis.org. Detil, data, hasil dll. pada dokumen ini telah ditulis ulang dan diverifikasi dengan sebaik mungkin pengetahuan dan tanggungjawab dari penulis dan editor. Bagaimanapun juga, dimungkinkan adanya kesalahan pada isi dokumen ini. Oleh karena itu, semua data tidak bertanggung jawab untuk setiap pekerjaan atau jaminan. Para penulis, editor dan penerbit tidak mengambil tanggung jawab atau kewajiban atas kegagalan dan konsekuensinya. Selalu terbuka bagi Anda untuk menunjukkan kemungkinan kesalahan. Dokumen ini telah diatur dengan reStructuredText. Ini tersedia sebagai sumber kode reST di github dan dalam jaringan (online) dengan format HTML dan PDF di http://www.qgis.org/en/docs/. Versi terjemahan dari dokumen ini dapat diunduh dalam beberapa format melalui proyek dokumentasi QGIS. Informasi lebih lanjut tentang kontribusi pada dokumen ini dan tentang menerjemahkannya, silakan kunjungi: http://www.qgis.org/wiki/. Tautan pada dokumen ini Dokumen ini berisi tautan internal dan eksternal. Silakan klik pada tautan internal akan membuka dokumen, sedangkan klik tautan eksternal membuka alamat internet. Dalam bentuk PDF, tautan internal dan eksternal diperlihatkan dengan warna biru dan ditangani oleh sistem peramban web (browser). Dalam bentuk HTML, menampilkan peramban web (browser) dan menangani keduanya secara identik. Pengguna, Penulis dan Editor Panduan Pemasangan dan Pemrograman (Coding): Tara Athan Peter Ersts Werner Macho Claudia A. Engel Larissa Junek Tim Sutton Astrid Emde

Radim Blazek Anne Ghisla Carson J.Q. Farmer Brendan Morely Diethard Jansen Alex Bruy Yves Jacolin

Godofredo Contreras Stephan Holl Tyler Mitchell David Willis Paolo Corti Raymond Nijssen Alexandre Neto

Otto Dassau N. Horning K. Koy Jürgen E. Fischer Gavin Macaulay Richard Duivenvoorde Andy Schmid

Martin Dobias Magnus Homann Lars Luthman Marco Hugentobler Gary E. Sherman Andreas Neumann Hien Tran-Quang

Hak Cipta (c) 2004 - 2013 QGIS Tim Pengembang Internet: http://www.qgis.org Lisensi dokumen ini Diizinkan untuk menyalin, mendistribusikan dan / atau memodifikasi dokumen ini di bawah syarat-syarat Lisensi Dokumentasi Bebas GNU (GNU Free Documentation License), atau versi yang lebih baru yang diterbitkan oleh Free Software Foundation; tanpa Bagian Invarian, tanpa Teks Sampul-Depan, dan tanpa Teks Sampul-Belakang. Salinan lisensi termasuk dalam Lampiran GNU Free Documentation License.

1

QGIS User Guide, Rilis 2.0

2

Bab 1. Pendahuluan

BAB 2

Konvensi

Bagian ini menjelaskan koleksi gaya seragam di seluruh panduan. Konvensi yang digunakan dalam panduan ini adalah sebagai berikut:

2.1 Konvensi GUI Gaya konvensi GUI dimaksudkan untuk meniru tampilan GUI. Secara umum, tujuannya adalah untuk menggunakan penampilan non-hover, sehingga pengguna dapat memindai visual GUI untuk menemukan sesuatu yang tampak seperti perintah di panduan. • Menu Pilihan: Lapisan → Tambah Lapisan Raster atau :menuselection:‘Pengaturan –> Toolbar –> Digitalisasi • Alat:

Tambah Lapisan Raster

• Tombol : [Simpan sebagai Default] • Kotak Judul: Properti Lapisan • Tab: Umum • Kotak Centang: • Tombol Radio:

Render Postgis SRID

EPSG ID

• Pilih Nomor: • Pilih String: • Lihat Berkas: • Pilih Warna: • Slider: • Masukkan Teks: Sebuah bayangan menunjukkan komponen GUI yang dapat diklik.

2.2 Konvensi Teks atau Papan Ketik Panduan ini juga mencakup gaya yang berhubungan dengan teks, perintah papan ketik dan pemrograman (coding) untuk menunjukkan entitas yang berbeda, seperti kelas, atau metode. Mereka tidak sesuai dengan setiap penampilan yang sebenarnya. • Pranala: http://qgis.org

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• Kombinasi Keystroke: tekan Ctrl+B, artinya tekan dan tahan tombol Ctrl dan tekan tombol B. • Nama Berkas: lakes.shp • Nama Kelas: LapisanBaru • Metode: classFactory • Server: myhost.de • Teks Pengguna: qgis --help Baris kode ditunjukkan dengan huruf fixed-width PROJCS["NAD_1927_Albers", GEOGCS["GCS_North_American_1927",

2.3 Petunjuk Spesifik Platform Urutan GUI dan sejumlah kecil teks dapat diformat inline: Klik QGIS.

Berkas

QGIS → Keluar untuk tutup

Hal ini menunjukkan bahwa di Linux, Unix dan platform Windows, klik pilihan menu pertama Berkas, kemudian Keluar dari menu dropdown, sementara di Macintosh OSX platform, klik QGIS menu pilihan pertama, kemudian Keluar dari menu dropdown. •

melakukan ini;

•

melakukan itu;

•

melakukan sesuatu yang lain.

atau sebagai paragraf. Lakukan ini dan ini dan ini. Kemudian melakukan ini dan ini dan ini dan ini dan ini dan ini dan ini dan ini dan ini. Lakukan itu. Kemudian melakukan itu dan itu dan itu dan itu dan itu dan itu dan itu dan itu dan itu dan itu dan itu dan itu dan itu dan itu dan itu. Layar yang muncul di seluruh buku panduan telah dibuat pada platform yang berbeda; platform ditunjukkan dengan ikon-platform tertentu pada akhir gambar keterangan.

4

Bab 2. Konvensi

BAB 3

Kata Pengantar

Selamat datang di dunia indah dari Sistem Informasi Geografis (GIS)! QGIS adalah Sistem Informasi Geografis Sumber Terbuka (Open Source). Proyek ini lahir di bulan Mei 2002 dan didirikan sebagai sebuah proyek di SourceForge pada bulan Juni tahun yang sama. Kami telah bekerja keras membuat perangkat lunak GIS (merupakan perangkat lunak proprietary tradisional mahal) prospek yang layak bagi siapa saja dengan akses dasar ke Personal Komputer. QGIS saat ini berjalan pada kebanyakan platform Unix, Windows, dan OS X. QGIS dikembangkan menggunakan toolkit Qt (http://qt.digia.com) dan C++. Ini berarti bahwa QGIS terasa cepat dan menyenangkan, antarmuka pengguna grafis yang mudah digunakan (GUI). QGIS bertujuan untuk menjadi GIS yang mudah digunakan, menyediakan fungsi dan fitur-fitur umum. Tujuan awalnya adalah untuk menyediakan penampil data GIS. QGIS telah mencapai titik dalam evolusi di mana ia digunakan sehari-hari oleh banyak orang untuk kebutuhan melihat data GIS mereka. QGIS mendukung sejumlah format data raster dan vektor, dengan dukungan format baru mudah ditambahkan dengan menggunakan arsitektur plugin. QGIS is released under the GNU General Public License (GPL). Developing QGIS under this license means that you can inspect and modify the source code, and guarantees that you, our happy user, will always have access to a GIS program that is free of cost and can be freely modified. You should have received a full copy of the license with your copy of QGIS, and you also can find it in Appendix GNU General Public License. Tip: Pembaruan Dokumentasi Versi terbaru dari dokumen http://www.qgis.org/en/docs/

ini

selalu

dapat

ditemukan

di

website

dokumentasi

QGIS

di

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Bab 3. Kata Pengantar

BAB 4

Keistimewaan

QGIS menawarkan banyak fungsi GIS umum yang disediakan oleh fitur inti dan plugin. Sebagai ringkasan singkat, disajikan dalam enam kategori untuk mendapatkan wawasan pertama.

4.1 Lihat data Anda dapat melihat dan overlay data vektor dan raster dalam format dan proyeksi yang berbeda tanpa konversi ke format internal maupun umum. Format yang didukung termasuk: • Spasial-enabled tabel dan tampilan menggunakan PostGIS, SpatiaLite dan MSSQL Spasial, Oracle Spasial, format vektor yang didukung oleh library OGR, termasuk ESRI shapefile, MapInfo, SDTS, GML dan banyak lagi, lihat bagian Pekerjaan dengan Data Vektor. • Format raster dan citra yang didukung dengan terpasangnya GDAL (Geospatial Data Abstraction Library) perpustakaan, seperti GeoTiff, Erdas Img., ArcInfo Ascii Grid, JPEG, PNG dan banyak lagi, lihat bagian Pekerjaan dengan Data Raster. • QGIS kerangka pengolahan untuk memanggil ratusan algoritma pihak asli dan ketiga dari QGIS, lihat bagian Processing Pengantar. • Data raster dan vektor GRASS dari basis data GRASS (lokasi/mapset), lihat bagian GRASS GIS Integration. • Online data spasial sebagai Layanan OGC Web, seperti (WMS, WMTS, WCS, WFS, WFS-T, ...), lihat bagian Pekerjaan dengan Data OGC. • Data OpenStreetMap, lihat bagian plugins_osm.

4.2 Jelajahi data dan menyusun peta Anda dapat membuat peta interaktif dan mengeksplorasi data spasial dengan GUI yang ramah. Banyak alat yang tersedia di GUI termasuk misalnya: • QGIS peramban web • On-the-fly proyeksi ulang • Pengelola DB • Penyusun Peta • Panel Peninjau • Bookmark spasial • Annotation tools • Identifikasi/pilih fitur • Sunting/lihat/cari atribut 7

QGIS User Guide, Rilis 2.0

• Pelabelan Fitur juga data yang didefinisikan • Perubahan simbologi vektor dan raster juga data yang didefinisikan • Penambahan lapisan graticule untuk membuat komposisi peta atlas • Hiasi peta Anda dengan panah arah utara, bar skala dan label hak cipta • Menyimpan dan mengembalikan proyek

4.3 Membuat, menyunting, mengelola dan ekspor data Anda dapat membuat, mengedit, mengelola dan ekspor lapisan vektor dan raster dalam beberapa format. QGIS menawarkan misalnya sebagai berikut: • Alat Digitalisasi yang didukung format OGR dan lapisan vektor GRASS • Membuat dan menyunting shapefile dan lapisan vektor GRASS • Geocode gambar dengan Plugin Georeferencer • Alat GPS untuk mengimpor dan mengekspor format GPX, dan mengkonversi format GPS lain ke GPX atau unduh/unggah langsung ke unit GPS (di Linux, usb: telah ditambahkan ke daftar perangkat GPS) • Memvisualisasikan dan mengedit data OpenStreetMap • Membuat tabel basis data spasial dari shapefile dengan Plugin Pengelola DB • Peningkatan penanganan tabel basis data spasial • Mengelola tabel atribut vektor • Simpan cuplikan layar sebagai gambar bergeoreferensi

4.4 Analisis data Anda dapat melakukan analisis data spasial pada basis data spasial dan format OGR lain yang didukung. QGIS saat ini menawarkan analisis vektor, sampling, geoprocessing, geometri dan aplikasi manajemen basis data. Anda juga dapat menggunakan aplikasi GRASS terintegrasi, yang meliputi fungsi GRASS lengkap lebih dari 400 modul (lihat bagian GRASS GIS Integration). Atau Anda bekerja dengan Plugin Processing, yang menyediakan kerangka analisis geospasial yang kuat untuk memanggil algoritma pihak asli dan ketiga dari QGIS, seperti GDAL, SAGA, GRASS, fTools dan banyak lagi (lihat bagian Pengantar).

4.5 Terbitkan peta di Internet QGIS dapat digunakan sebagai WMS, WMTS, WMS-C atau WFS dan WFS-T client, dan sebagai WMS atau WFS server (lihat bagian Pekerjaan dengan Data OGC). Selain itu Anda dapat mengekspor data, mempublikasikan mereka di internet menggunakan webserver dengan UMN MapServer atau GeoServer yang terpasang.

4.6 Memperpanjang fungsionalitas QGIS melalui plugin QGIS dapat disesuaikan dengan kebutuhan khusus Anda dengan arsitektur plugin yang dapat diperpanjang. QGIS menyediakan perpustakaan (libraries) yang dapat digunakan untuk membuat plugin. Anda dapat membuat aplikasi baru dengan C++ atau Python!

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4.6.1 Inti Plugin 1. Rekaman Koordinat (Tetikus merekam koordinat di CRS yang berbeda) 2. DB Manager (Pertukaran, mengedit dan melihat lapisan dan tabel; mengeksekusi query SQL) 3. Diagram Overlay (Menempatkan diagram pada lapisan vektor) 4. Dxf2Shp Converter (Mengubah DXF ke Shape) 5. eVIS (Event Visualization Tool) 6. fTools (Alat untuk analisis dan mengelola data vektor) 7. GDALTools (Integrasi alat GDAL ke dalam QGIS) 8. Georeferencer GDAL (Menambahkan informasi proyeksi ke raster menggunakan GDAL) 9. Alat GPS (Memuat dan impor data GPS) 10. GRASS (GRASS GIS integrasi) 11. Heatmap (Membangkitkan raster heatmap dari data titik) 12. Llugin Interpolation (interpolasi berdasarkan simpul dari lapisan vektor) 13. Ekspor Mapserver (Ekspor berkas proyek QGIS ke berkas peta MapServer) 14. Penyuntingan Luar Jaringan (Izinkan menyunting luar jaringan dan sinkronisasi dengan basis data) 15. Plugin Open Layer (lapisan OpenStreetMap, Google Maps, Bing Maps dan banyak lagi) 16. Oracle Spatial GeoRaster 17. Processing (formerly SEXTANTE) 18. Analisis terrain raster (analisis terrain berbasis raster) 19. Plugin road graph (Analisis jaringan terpendek) 20. Spatial Query Plugin 21. SPIT (Impor Shapefile ke PostgreSQL/PostGIS) 22. Plugin SQL Anywhere (Menyimpan lapisan vektor dengan basis data SQL Anywhere) 23. Topologi Checker (Menemukan kesalahan topologi dalam lapisan vektor) 24. Plugin Zonal statistics (hitung, jumlah, rata-rata raster untuk setiap poligon dari lapisan vektor)

4.6.2 Plugin Eksternal Python QGIS menawarkan semakin banyak plugin python eksternal yang diberikan oleh masyarakat. Plugin ini berada di plugin repositori resmi, dan dapat dengan mudah dipasang menggunakan Python Plugin Installer (lihat bagian Memuat Plugin eksternal QGIS).

4.7 Python Console Untuk scripting, memungkinkan untuk mengambil keuntungan dari konsol Python terintegrasi. Hal ini dapat dibuka dari menu: Plugins → Python Console. Konsol terbuka sebagai jendela utilitas non-modal. Untuk interaksi dengan lingkungan QGIS, ada variabel qgis.utils.iface, yang merupakan contoh dari QgsInterface. Interface ini memungkinkan akses ke kanvas peta, menu, toolbar dan bagian lain dari aplikasi QGIS. Untuk informasi lebih lanjut tentang bekerja dengan plugin dan aplikasi Python Console dan Programming Py|qg|, silakan lihat http://www.qgis.org/html/en/docs/pyqgis_developer_cookbook/index.html.

4.7. Python Console

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Bab 4. Keistimewaan

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Apa yang baru pada QGIS 2.0

Harap dicatat bahwa ini adalah rilis dalam ‘cutting edge’ seri rilis kami. Dengan demikian mengandung fitur baru dan memperluas program antarmuka dibanding QGIS 1.8.0. Kami menyarankan agar Anda menggunakan versi ini daripada rilis sebelumnya. Rilis ini meliputi ratusan perbaikan kesalahan (bug) dan banyak fitur baru dan perangkat tambahan yang akan dijelaskan dalam panduan ini. Juga bandingkan dengan visual log perubahan (changelog) di http://changelog.linfiniti.com/qgis/version/200/

5.1 Antarmuka Pengguna • Tema ikon baru: Kami telah memperbarui tema ikon kami untuk menggunakan tema ‘GIS’ memperkenalkan peningkatan konsistensi dan profesionalisme antar muka pengguna QGIS. • Tab samping, kotak kelompok lipat: Kami memiliki standar tata letak tab dan memperkenalkan kotak kelompok dilipat ke dalam banyak dialog untuk membuat berbagai pilihan navigasi yang lebih mudah, dan untuk membuat lebih baik menggunakan layar real estat. • Notifikasi halus: Dalam banyak kasus kami ingin memberitahu Anda tentang sesuatu, tetapi kami tidak ingin menghentikan pekerjaan anda. Dengan sistem notifikasi baru |ql| dapat memberitahu Anda tentang pentingnya informasi lewat bar pesan (warna tergantung pada pentingnya pesan) yang muncul di bagian atas kanvas peta tapi tidak mengganggu Anda untuk berurusan dengan itu jika Anda sedang sibuk melakukan pekerjaan yang lain. Programmer dapat membuat notifikasi tersebut (misalnya dari plugin) menggunakan API python kami. • Application custom font and Qt stylesheet: Sistem huruf yang digunakan untuk aplikasi antarmuka pengguna sekarang dapat diatur. Plugin C++ atau Python yang merupakan anak dari aplikasi GUI QGIS atau telah disalin/menerapkan aplikasi GUI stylesheet dapat mewarisi gaya, yang berguna untuk perbaikan GUI di seluruh platform dan bila menggunakan kustom widget Qt QGIS, seperti QgsCollapsibleGroupBox. • Live color chooser dialogs and buttons: Setiap warna tombol pemilih seluruh antarmuka telah diperbarui untuk memberikan umpan balik visual apakah memiliki transparan warna saat ini, atau ‘alpha,’ komponen. Warna pemilih dibuka oleh tombol warna baru, sekarang akan menjadi default untuk sistem operasi. Jika pengguna menggunakan live-update dialog pemilih warna diperiksa di bawah Options -> General -> Application, perubahan apapun dalam pemilih warna akan segera ditampilkan dalam warna tombol dan untuk setiap item saat ini sedang diedit, mana yang berlaku. • Anotasi SVG: Dengan QGIS versi 2.0 kini, Anda dapat menambahkan anotasi (keterangan) SVG ke peta Anda - baik disematkan ke tempat tertentu atau dalam posisi relatif di atas kanvas peta.

5.2 Penyedia Data • Dukungan Stasial Oracle: QGIS versi 2.0 kini termasuk Dukungan Stasial Oracle.

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• Penyedia Layanan Cakupan Web (Web Coverage Service): QGIS kini disediakan dukungan asli untuk lapisan Layanan Cakupan Web (Web Coverage Service) - proses untuk menambahkan WCS mirip dengan menambahkan lapisan (layer) WMS atau WFS. • Raster Data Provider overhaul: Sistem penyedia data raster telah dirombak total. Salah satu fitur baru terbaik yang berasal dari pekerjaan ini adalah kemampuan Layer -> Save As... untuk menyimpan lapisan (layer) raster sebagai lapisan (layer) baru. Dalam proses ini, Anda dapat memotong, resample, reproject lapisan kedalam Sistem Referensi Koordinat (Coordinate Reference System) baru. Anda juga bisa menyimpan lapisan raster sebagai gambar (rendered), jadi jika Anda misalnya memiliki raster band tunggal yang telah menerapkan palet warna, Anda dapat menyimpan lapisan (layer) ke lapisan (layer) RGB ber-georeferensi. • Raster 2% cumulative cut by default: Banyak produk raster citra memiliki sejumlah besar outlier menghasilkan gambar yang memiliki penampilan washed out. QGIS versi 2.0 memperkenalkan kontrol yang lebih baik atas proses rendering raster, termasuk menggunakan kumulatif 2% - 98% persen dipotong secara default ketika menentukan ruang warna gambar. • Identifikasi format WMS: Memilih format mengidentifikasi hasil untuk lapisan (layer) WMS jika beberapa dikenal format yang didukung oleh server. Format yang didukung adalah HTML, fitur (GML) dan teks biasa. Jika format (GML) dipilih, hasilnya adalah dalam bentuk yang sama seperti untuk lapisan vektor, geometri dapat disorot dan fitur termasuk atribut dan geometri dapat disalin ke papan klip dan disisipkan ke lapisan lain. • Dukungan WMTS: Klien WMS QGIS kini didukung WMTS (Web Mapping Tile Service) termasuk pemilihan sub-dataset seperti irisan waktu. Saat menambahkan lapisan (layer) WMS dari server compliant, Anda akan diminta untuk memilih tampilan irisan waktu.

5.3 Simbologi • Properti data yang didefinisikan: Dengan properti data baru yang didefinisikan, memungkinkan untuk mengontrol jenis simbol, ukuran, warna, rotasi, dan banyak properti lain melalui fitur atribut. • Manajemen lapisan perbaikan simbol: Simbol lapisan (layer) baru menggunakan gambaran jelas, dengan tata letak pohon-terstruktur yang memungkinkan untuk akses mudah dan cepat ke semua simbol lapisan (layer). • Dukungan transparansi dalam definisi warna: Pada kebanyakan tempat dimana Anda memilih warna, kini QGIS memungkinkan Anda untuk menentukan alpha channel (menentukan harus seberapa transparan warna). Hal ini memungkinkan Anda membuat peta tampak hebat dan untuk menyembunyikan data dengan mudah bahwa Anda tidak ingin pengguna melihatnya. • Kontrol Warna Lapisan (layer) Raster: QGIS versi 2.0 memungkinkan Anda secara tepat mengontrol persis bagaimana Anda ingin lapisan (layer) raster muncul. Anda kini memiliki kontrol penuh atas kecerahan (brightness), kontras (contrast) dan saturasi (saturation) lapisan (layer) raster. Bahkan ada pilihan tampilan raster skala abu-abu (grayscale) atau dengan warna tertentu. • Salin simbologi antar lapisan (layer): Sekarang sangat mudah menyalin simbologi dari satu lapisan (layer) ke lapisan lain. Jika Anda bekerja dengan beberapa lapisan yang sama, Anda bisa klik kanan pada salah satu lapisan, pilih Salin (Copy Style) dari menu utama dan kemudian klik-kanan pada layer lain dan memilih Tempel (Paste Style). • Cara menyimpan dalam basis data Anda: Jika Anda menggunakan penyimpanan data basis data vektor, sekarang Anda cara penyimpanan definisi lapisan (layer) langsung dalam basis data. Hal ini membuat mudah untuk berbagi gaya lapisan (layer) dalam suatu perusahaan atau lingkungan multi-pengguna. • Dukungan warna landai (ramp): Warna landai (ramp) kini tersedia di banyak tempat pengaturan simbologi QGIS, set extensible warna landai (ramp). Anda juga dapat desain sendiri dan banyak tema cpt-kota yang termasuk dalam QGIS sekarang ‘out of the box’. Bahkan warna landai (ramp) didukung pengaturan transparansi! • Set custom default styles for all layer types: Kini QGIS memungkinkan Anda mengontrol bagaimana lapisan (layer) baru akan ditarik ketika mereka tidak memiliki gaya (style) .qml. Anda juga dapat mengatur default tingkat transparansi untuk lapisan (layer) baru dan apakah simbol harus memiliki warna acak. 12

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5.4 Penyusun Peta • Pokok-pokok Peta HTML: Anda sekarang dapat menempatkan elemen html ke peta Anda. • Garis Bantu Otomatis: Menyelaraskan item peta sangat penting untuk membuat peta dicetak dengan bagus. Garis bantu otomatis telah ditambahkan untuk memudahkan penyelarasan penyusun objek hanya dengan mendekatkan sebuah benda dengan yang lain. • Garis Bantu Manual: Kadang-kadang Anda perlu untuk menyelaraskan objek dengan jarak tertentu pada penyusun peta. Dengan garis bantu manual, Anda dapat menambahkan garis bantu secara manual yang memungkinkan benda menyelaraskan lebih baik menggunakan keselarasan umum. Cukup tarik dari atas atau samping untuk menambahkan garis bantu baru. • Menghasilkan Serangkaian Peta: Pernahkah diperlukan cara menghasilkan serangkaian peta? Tentu saja Anda membutuhkan. Sekarang dalam Penyusun Peta telah disediakan layanan menghasilkan serangkaian peta menggunakan fitur atlas. Cakupan lapisan (layer) bisa titik, garis, poligon, dan sekarang yang fitur data atribut tersedia dalam label untuk penggantian nilai data. • Dukungan banyak halaman (Multipage): Sebuah jendela penyusun peta tunggal kini dapat berisi lebih dari satu halaman. • Expressions in composer labels: Item penyusun label pada versi 1,8 sangat terbatas dan hanya diperbolehkan tanda tunggal $CURRENT_DATE yang digunakan. Pada versi 2.0 telah ditambahkan dukungan ekspresi penuh dengan keleluasaan mengelola label akhir. • Dukungan tampilan otomatis dalam bingkai peta: Perlu menunjukkan daerah saat ini pada bingkai peta utama di jendela tampilan yang lebih kecil. Sekarang, bingkai peta memiliki kemampuan untuk menunjukkan luasan dan akan memperbarui ketika pindah. Dengan menggunakan fitur pembuat atlas sekarang inti dalam penyusun peta memungkinkan untuk menghasilkan beberapa peta. Sekilas gaya bingkai menggunakan gaya yang sama sebagai objek peta poligon normal sehingga kreativitas Anda tidak pernah dibatasi. • Menggabung Lapisan (Layer blending): Menggabung lapisan memungkinkan untuk menggabungkan lapisan (layer) dalam cara-cara baru dan menarik. Sementara di versi lama, semua dapat Anda lakukan untuk membuat lapisan transparan, kini Anda dapat memilih seperti “multiply”, “darken only”, dan masih banyak lagi. Penggabungan (blending) dapat digunakan dalam tampilan peta normal maupun di penyusun peta cetak. Untuk panduan singkat tentang cara menggunakan penggabungan (blending) di penyusun peta cetak untuk membuat gambar latar belakang, lihat “Vintage map design using QGIS”. • Dukungan Label HTML: Dukungan label HTML telah ditambahkan pada penyusun peta untuk memberikan kontrol yang lebih besar pada peta akhir Anda. Label HTML mendukung penuh lembar gaya css, html, dan bahkan javascript. • Legenda multi kolom: Sekarang penyusun legenda telah didukung multi kolom. Memisahkan dari satu lapisan (layer) dengan banyak kelas menjadi beberapa kolom adalah opsional. Lapisan simbol tunggal ditambahkan secara default sebagai item baris tunggal. Tiga gaya yang berbeda dapat diberikan untuk lapisan/judul grup: Grup, sub grup atau tersembunyi (hidden). Gaya judul visual yang memungkinkan pengelompokan item dengan leluasa. Sebagai contoh, simbol lapisan tunggal dapat ditampilkan sebagai item baris tunggal atau dengan judul lapisan (seperti versi 1.8), simbol dari beberapa lapisan (layer) dapat dikelompokkan ke dalam satu kelompok (menyembunyikan judul) dll. Fitur penghitungan bisa ditambahkan ke label. • Pembaruan manajemen penyusun peta: Perbaikan berikut telah dibuat untuk manajemen penyusun peta: – Sekarang nama penyusun dapat didefinisikan pada penciptaan, opsional memilih mulai dari nama penyusun lainnya – Sekarang penyusun bisa disalin/duplikasi – Baru dari Template dan dari Spesifik (dalam Manajer Penyusun) menciptakan penyusun dari template yang terletak di manapun pada filesystem – Sekarang proyek induk bisa disimpan secara langsung dari area kerja penyusun peta – Semua tindakan manajemen penyusun kini dapat diakses langsung dari area kerja penyusun peta

5.4. Penyusun Peta

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5.5 Pelabelan • Sistem pelabelan baru: Sistem pelabelan telah benar-benar dirombak - kini mencakup banyak fitur baru seperti drop shadow, ‘highway shields’, banyak pilihan dan berbagai peningkatan kinerja. Kami perlahanlahan melakukan jauh dari sistem ‘label tua’, meskipun Anda masih menemukan fungsi yang tersedia untuk rilis ini, Anda berharap bahwa itu akan hilang dalam rilis tindak lanjut. • Expression based label properties: Kekuatan penuh label dan aturan ekspresi yang normal kini dapat digunakan untuk properti label. Hampir setiap properti dapat didefinisikan dengan nilai ekspresi atau kolom nilai memberikan Anda kontrol lebih besar atas hasil label. Ekspresi dapat merujuk ke kolom (misalnya mengatur ukuran font dengan nilai ‘huruf’) atau dapat mencakup logika yang lebih kompleks. • Mesin pelabelan yang usang: Penggunaan mesin pelabelan tua tersedia dalam QGIS Panel -> Peramban (2)) untuk interaksi drag-n-drop antara panel peramban – Saat ini ikon disaring berdasarkan tipe grup (filesystem, basis data, server peta) – Saat ini properti lapisan (layer) memiliki visual layout lebih baik

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Bab 5. Apa yang baru pada QGIS 2.0

BAB 6

Memulai

Bab ini memberikan gambaran singkat cara memasang QGIS, beberapa contoh data dari QGIS halaman web dan menjalankan sesi pertama memvisualisasikan lapisan (layer) raster dan vektor sederhana.

6.1 Pemasangan (Instalasi) Pemasangan QGIS sangat sederhana. Standar paket installer tersedia untuk MS Windows dan Mac OS X. Tersedia paket binary GNU/Linux (rpm dan deb) atau repositori perangkat lunak untuk menambah manajer instalasi. Dapatkan informasi terakhir paket binari pada website QGIS http://download.qgis.org.

6.1.1 Pemasangan dari sumber Jika Anda perlu membangun QGIS dari sumber, silakan lihat petunjuk instalasi. Mereka didistribusikan dengan kode sumber QGIS dalam sebuah berkas yang bernama ‘INSTALL’. Anda juga bisa menemukannya di dalam jaringan (online) di http://htmlpreview.github.io/?https://raw.github.com/qgis/QGIS/master/doc/INSTALL.html

6.1.2 Pemasangan pada media eksternal QGIS memungkinkan untuk menentukan opsi --configpath yang menimpa path default (misal di linux ~/.qgis2) untuk konfigurasi pengguna dan QSettings menggunakan direktori ini juga. Hal ini memungkinkan pengguna yang membawa installer QGIS pada flash drive bersama dengan semua plugin dan pengaturan. Bandingkan dengan bagian Menu Sistem.

6.2 Contoh data Panduan pengguna berisi contoh-contoh berdasarkan contoh dataset QGIS. installer Windows memiliki pilihan untuk mengunduh contoh dataset QGIS. Jika dicentang, data akan diunduh ke folder My Documents Anda dan ditempatkan dalam folder bernama GIS database. Anda dapat menggunakan Windows Explorer untuk memindahkan folder ini ke setiap lokasi yang nyaman. Jika Anda tidak memilih kotak centang untuk memasang contoh dataset selama instalasi QGIS, Anda dapat • menggunakan data GIS yang Anda miliki; • unduh contoh data di http://download.osgeo.org/qgis/data/qgis_sample_data.zip; atau • hapus (uninstall) QGIS dan memasang ulang dengan opsi unduh data, hanya jika solusi di atas tidak berhasil. untuk GNU/Linux dan Mac OSX belum ada paket instalasi dataset yang tersedia sebagai rpm, deb atau dmg. Untuk menggunakan contoh dataset unduh berkas ZIP qgis_sample_data di http://download.osgeo.org/qgis/data/qgis_sample_data.zip dan ekstrak arsip ZIP di sistem Anda. Dataset Alaska mencakup semua data GIS yang digunakan sebagai contoh dan cuplikan layar di buku panduan, dan termasuk 17

QGIS User Guide, Rilis 2.0

basis data kecil GRASS. Proyeksi contoh dataset QGIS adalah Alaska Albers Equal Area dengan satuan kaki (feet). Kode EPSG 2964. PROJCS["Albers Equal Area", GEOGCS["NAD27", DATUM["North_American_Datum_1927", SPHEROID["Clarke 1866",6378206.4,294.978698213898, AUTHORITY["EPSG","7008"]], TOWGS84[-3,142,183,0,0,0,0], AUTHORITY["EPSG","6267"]], PRIMEM["Greenwich",0, AUTHORITY["EPSG","8901"]], UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9108"]], AUTHORITY["EPSG","4267"]], PROJECTION["Albers_Conic_Equal_Area"], PARAMETER["standard_parallel_1",55], PARAMETER["standard_parallel_2",65], PARAMETER["latitude_of_center",50], PARAMETER["longitude_of_center",-154], PARAMETER["false_easting",0], PARAMETER["false_northing",0], UNIT["us_survey_feet",0.3048006096012192]]

Jika Anda berniat untuk menggunakan frontend QGIS sebagai grafis GRASS, Anda dapat menemukan pilihan contoh lokasi (misalnya Spearfish atau South Dakota) di situs resmi GRASS GIS http://grass.osgeo.org/download/sample-data/.

6.3 Sesi Contoh Sekarang Anda QGIS sudah terpasang dan contoh dataset tersedia, kami ingin menunjukkan sesi contoh QGIS singkat dan sederhana. Kami akan memvisualisasikan lapisan (layer) raster dan vektor. Kami akan menggunakan lapisan (layer) raster tutupan lahan qgis_sample_data/raster/landcover.img dan lapisan (layer) vektor danau qgis_sample_data/gml/lakes.gml.

6.3.1 Mulai QGIS •

Mulai QGIS dengan mengetik: “QGIS” di terminal, atau menggunakan bineri precompiled, menggunakan menu Aplikasi.

•

Mulai QGIS menggunakan menu Start atau shortcut desktop, atau dobel klik di berkas proyek QGIS.

•

Dobel klik ikon pada folder Aplikasi.

6.3.2 Muat lapisan (layer) raster dan vektor dari contoh dataset 1. Klik di ikon

Load Raster

2. Lihat ke folder qgis_sample_data/raster/, pilih berkas ERDAS Img landcover.img dan klik [Buka]. 3. Jika berkas tidak ada dalam daftar, periksa apakah combobox jenis berkas di bagian bawah dialog diatur pada jenis yang tepat, dalam kasus ini “Erdas Imagine Images (*.img, *.IMG)”. 4. Sekarang klik di ikon 5.

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Load Vector

.

Berkas harus dipilih sebagai Jenis Sumber baru Tambah Lapisan Vektor. Sekarang klik [Lihat] untuk memilih lapisan (layer) vektor. Bab 6. Memulai

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6. Lihat ke folder qgis_sample_data/gml/, pilih “GML” dari combobox jenis berkas, kemudian pilih berkas GML lakes.gml dan klik [Buka], kemudian di dialog Tambah Vektor klik [OK]. 7. Perbesar sedikit ke daerah favorit Anda dengan beberapa danau. 8. Dobel klik lapisan (layer) lakes di legenda peta untuk membuka dialog Properti. 9. Klik menu Style dan pilih biru pada isian warna. Label lapisan ini dengan kotak centang untuk mengaktifkan label dan 10. Klik menu Label dan centang memilih bidang “NAMES” sebagai bidang isian label. 11. Untuk memudahkan pembacaan label, Anda dapat menambahkan penyangga (buffer) putih di sekitar mereka, dengan klik “Buffer” dalam daftar sebelah kiri, periksa penyangga (buffer).

Draw text buffer dan pilih 3 sebagai ukuran

12. Klik [Terapkan], periksa apakah hasilnya baik dan terakhir klik [OK]. Anda dapat melihat betapa mudahnya untuk memvisualisasikan lapisan (layer) raster dan vektor dalam QGIS. Mari kita lanjutkan ke bagian berikut untuk mempelajari lebih lanjut tentang fungsi, fitur dan pengaturan yang tersedia dan bagaimana menggunakannya.

6.4 Memulai dan Menghentikan QGIS Di bagian Sesi Contoh Anda sudah belajar bagaimana memulai QGIS. Kami akan mengulanginya di sini dan Anda akan melihat QGIS juga menyediakan opsi baris perintah lebih lanjut. •

Dengan asumsi bahwa QGIS dipasang di PATH, Anda dapat memulai QGIS dengan mengetik: qgis pada terminal atau dengan mengklik dobel pada link aplikasi QGIS (atau shortcut) pada desktop atau dalam menu aplikasi.

•

Mulai QGIS menggunakan menu Start atau shortcut dekstop, atau dobel klik pada berkas proyek QGIS.

•

Dobel klik ikon di folder Aplikasi Anda. Jika Anda memulai QGIS di terminal, jalankan /path-toinstallation-executable/Contents/MacOS/Qgis.

Untuk menghentikan QGIS, klik menu

Berkas

QGIS → Keluar, atau menggunakan shortcut Ctrl+Q.

6.5 Pilihan Baris Perintah QGIS mendukung sejumlah pilihan ketika dimulai dari baris perintah. Untuk mendapatkan daftar opsi, enter qgis --help pada baris perintah. Pernyataan penggunaan untuk QGIS adalah: qgis --help QGIS - 2.0.1-Dufour ’Dufour’ (exported) QGIS is a user friendly Open Source Geographic Information System. Usage: qgis [OPTION] [FILE] options: [--snapshot filename] emit snapshot of loaded datasets to given file [--width width] width of snapshot to emit [--height height] height of snapshot to emit [--lang language] use language for interface text [--project projectfile] load the given QGIS project [--extent xmin,ymin,xmax,ymax] set initial map extent [--nologo] hide splash screen [--noplugins] don’t restore plugins on startup [--nocustomization] don’t apply GUI customization [--optionspath path] use the given QSettings path [--configpath path] use the given path for all user configuration [--code path] run the given python file on load

6.4. Memulai dan Menghentikan QGIS

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[--help]

this text

FILES: Files specified on the command line can include rasters, vectors, and QGIS project files (.qgs): 1. Rasters - Supported formats include GeoTiff, DEM and others supported by GDAL 2. Vectors - Supported formats include ESRI Shapefiles and others supported by OGR and PostgreSQL layers using the PostGIS extension

Tip: Contoh Menggunakan argumen baris perintah Anda dapat memulai QGIS dengan menentukan satu atau lebih berkas data pada baris perintah. Misalnya, dengan asumsi Anda berada di direktori qgis_sample_data, Anda bisa memulai QGIS dengan berkas lapisan vektor dan raster diatur untuk dimuat pada startup dengan menggunakan perintah berikut: qgis ./raster/landcover.img ./gml/lakes.gml Pilihan baris perintah --snapshot Pilihan ini memungkinkan Anda untuk membuat cuplikan layar dalam format PNG dari tampilan saat ini. Hal ini sangat berguna ketika Anda memiliki banyak proyek dan ingin menghasilkan cuplikan layar dari data Anda. Saat ini menghasilkan berkas PNG dengan piksel 800x600. Hal ini dapat diadaptasi dengan menggunakan argumen baris perintah --width dan --height. Nama berkas bisa ditambahkan setelah --snapshot. Pilihan baris perintah --lang Berdasarkan QGIS lokal Anda, pilih lokalisasi yang benar. Jika Anda ingin mengubah bahasa, Anda dapat menentukan kode bahasa. Sebagai contoh: --lang=id QGIS dimulai menggunakan lokal Indonesia. Daftar bahasa saat ini yang didukung dengan kode bahasa dan status disediakan di http://hub.qgis.org/wiki/quantumgis/GUI_Translation_Progress Baris perintah --project Memulai QGIS dengan berkas proyek yang sudah ada. Hanya tambahkan baris perintah --project ikuti nama berkas proyek yang akan dibuka dan QGIS akan membukanya dengan memuat semua lapisan (layer). Baris perintah --extent Untuk memulai dengan peta batas tertentu menggunakan opsi ini. Anda perlu menambahkan kotak bounding sejauh Anda dalam urutan dipisahkan oleh koma: --extent xmin,ymin,xmax,ymax

Baris perintah --nologo Argumen baris perintah ini menyembunyikan layar splash ketika Anda mulai QGIS. Baris perintah --noplugins Jika Anda mengalami kesulitan pada saat startup dengan plugin, Anda dapat menghindari beban mereka pada saat startup. Mereka masih akan tersedia di Pengelola Plugin after-wards. Baris perintah --nocustomization Menggunakan argumen baris perintah ini kustomisasi GUI yang ada tidak akan diterapkan pada saat startup. Baris perintah --optionspath Anda dapat memiliki beberapa konfigurasi dan memutuskan mana yang akan digunakan ketika memulai QGIS menggunakan opsi ini. Lihat Opsi untuk memeriksa sistem operasi mana menyimpan berkas pengaturan. Saat ini tidak ada cara untuk menentukan berkas yang mana untuk menulis pengaturan, oleh karena itu, Anda dapat membuat salinan pengaturan berkas asli dan ganti namanya. Baris perintah --configpath

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Pilihan ini mirip dengan yang di atas, tapi selanjutnya menimpa path default (~/.qgis) untuk konfigurasi pengguna dan QSettings untuk menggunakan direktori ini juga. Hal ini memungkinkan pengguna mis membawa instalasi QGIS pada flash drive bersama dengan semua plugin dan pengaturan.

6.6 Proyek Sesi QGIS Anda dianggap sebagai Project. QGIS bekerja pada satu proyek pada satu waktu. Pengaturan yang baik dianggap sebagai per-proyek, atau sebagai default untuk proyek-proyek baru (lihat Bagian Opsi). QGIS dapat menyimpan kerja Anda ke dalam sebuah berkas proyek dengan menggunakan pilihan menu Proyek → atau Proyek →

Simpan

Simpan Sebagai.

Memuat proyek tersimpan ke dalam sesi QGIS menggunakan Proyek → plate atau Proyek → Buka yang baru teradi.

Buka ..., Project → Baru dari tem-

Baru. Pilihan menu ini akan Jika Anda ingin membersihkan sesi Anda dan memulai baru lagi, pilih Proyek → meminta Anda untuk menyimpan proyek yang telah ada jika perubahan yang telah dibuat sejak dibuka atau yang terakhir disimpan. Jenis-jenis informasi yang disimpan dalam berkas proyek meliputi: • Lapisan (layer) yang ditambahkan • Properti lapisan (layer), termasuk simbolisasi • Proyeksi untuk tampilan peta • Tampilan terkahir Berkas proyek disimpan dalam format XML, sehingga memungkinkan untuk mengedit berkas diluar QGIS jika Anda tahu apa yang Anda lakukan. Format berkas telah diperbaharui beberapa kali dibanding versi QGIS sebelumnya. Berkas proyek dari versi QGIS yang lebih tua mungkin tidak bekerja dengan baik lagi. Harus dibuat sadar akan hal ini, di Umum tab under Pengaturan → Opsi Anda dapat memilih: Prompt untuk menyimpan proyek dan perubahan sumber data bila diperlukan Peringatkan ketika membuka berkas proyek QGIS yang disimpan dengan versi lama

6.7 Keluaran (Output) Ada beberapa cara untuk menghasilkan keluaran (output) dari sesi QGIS Anda. Kita telah membahasnya pada Bagian Proyek menyimpan berkas proyek. Berikut ini adalah contoh cara lain untuk menghasilkan keluaran (output) berkas: Simpan sebagai Gambar • Menu opsi Proyek → membuka dialog berkas di mana Anda memilih nama, path dan jenis gambar (format PNG atau JPG). Sebuah berkas dengan ekstensi PNGW atau JPGW disimpan dalam folder sama dengan gambar yang mempunyai georeferensi.

• Menu opsi Proyek → Penyusun Cetak Baru membuka dialog di mana Anda dapat me-layout dan mencetak kanvas peta saat ini (lihat Bagian Print Composer).

6.6. Proyek

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22

Bab 6. Memulai

BAB 7

QGIS GUI

Ketika QGIS dimulai, Anda akan disajikan tampilan GUI seperti gambar dibawah ini (nomer 1 sampai 5 dalam lingkaran kuning mengacu pada 5 area utama antarmuka yang dibahas dibawah ini:

Gambar 7.1: GUI QGIS dengan contoh data Alaska

Catatan: Jendela dekorasi Anda (judul bar , dll) dapat terlihat berbeda tergantung pada sistem operasi dan window manager Anda . GUI QGIS dibagi dalam lima area: 1. Bar Menu 2. Bar Tool 3. Legenda Peta

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4. Tampilan Peta 5. Status Bar Kelima komponen antarmuka QGIS dijelaskan secara lebih rinci dalam bagian berikut. Lebih dari dua bagian dijelaskan di shortcut papan ketik dan bantuan.

7.1 Bar Menu Menu bar memberikan akses ke berbagai fitur QGIS menggunakan standar hirarki menu. Menu-menu utama dan ringkasan dari beberapa menu pilihan yang tercantum di bawah ini, bersama-sama dengan ikon dari alat yang sesuai seperti yang ditampilkan pada toolbar, seperti shortcut papan ketik. Shortcut papan ketik juga dapat dikonfigurasi secara manual (shortcut yang disajikan dalam bagian ini adalah standar), menggunakan alat [Konfigurasi Shortcut] dalam menu Pengaturan. Meskipun sebagian besar pilihan menu memiliki alat yang sesuai dan sebaliknya, menu tidak terorganisir seperti toolbar. Toolbar yang berisi alat ini bisa terdaftar setelah setiap pilihan menu diisi pada kotak centang. Beberapa pilihan menu hanya muncul jika plugin yang sesuai dimuat. Untuk informasi lebih lanjut tentang alat dan toolbar, lihat Bagian Toolbar.

7.1.1 Proyek Pilihan Menu

Shortcut

Referensi

Toolbar

Baru

Ctrl+N

lihat Proyek

Proyek

Ctrl+O

lihat Proyek lihat Proyek lihat Proyek

Proyek Proyek

Simpan

Ctrl+S

lihat Proyek

Proyek

Simpan sebagai

Ctrl+Shift+S

lihat Proyek

Proyek

Buka Baru dari template → Buka terkahir dikerjakan →

lihat Keluaran (Output)

Simpan sebagai Gambar Penyusun cetak baru

Ctrl+P

Manajer Penyusun ... Penyusun Cetak → Keluar |qg|

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lihat Print Composer

Proyek

lihat Print Composer lihat Print Composer

Proyek

Ctrl+Q

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7.1.2 Edit Pilihan Menu

Shortcut

Referensi

Toolbar

Kembali

Ctrl+Z

lihat Advanced digitizing

Digitalisasi Lanjutan

Ulangi

Ctrl+Shift+Z

lihat Advanced digitizing

Digitalisasi Lanjutan

Ambil Fitur

Ctrl+X

lihat Digitizing an existing layer

Digitalisasi

Salin Fitur

Ctrl+C

lihat Digitizing an existing layer

Digitalisasi

Tempel Fitur

Ctrl+V

lihat Digitizing an existing layer

Digitalisasi

Tambah Fitur

Ctrl+.

lihat Digitizing an existing layer

Digitalisasi

Pindah Fitur

lihat Digitizing an existing layer

Digitalisasi

Hapus yand dipilih

lihat Digitizing an existing layer

Digitalisasi

Rotasi Fitur

lihat Advanced digitizing

Digitalisasi Lanjutan

Sederhanakan Fitur

lihat Advanced digitizing

Digitalisasi Lanjutan

Tambah Ring

lihat Advanced digitizing

Digitalisasi Lanjutan

Tambah Bagian

lihat Advanced digitizing

Digitalisasi Lanjutan

Hapus Ring

lihat Advanced digitizing

Digitalisasi Lanjutan

Hapus bagian

lihat Advanced digitizing

Digitalisasi Lanjutan

Bentuk Ulang Fitur

lihat Advanced digitizing

Digitalisasi Lanjutan

Offset Curves

lihat Advanced digitizing

Digitalisasi Lanjutan

Pisah Fitur

lihat Advanced digitizing

Digitalisasi Lanjutan

Gabung Fitur Terpilih

lihat Advanced digitizing

Digitalisasi Lanjutan

Gabung Attr. Fitur Terpilih

lihat Advanced digitizing

Digitalisasi Lanjutan

Node Tool

lihat Digitizing an existing layer

Digitalisasi

Rotasi Simbol Titik

lihat Advanced digitizing

Digitalisasi Lanjutan

Toggle mengedit Setelah mengaktifkan mode untuk lapisan (layer), Anda menemukan ikon Add Feature di menu Edit tergantung pada jenis lapisan (titik, garis atau poligon).

7.1.3 Edit (ekstra) Pilihan Menu

Referensi

Toolbar

Tambah Fitur

lihat Digitizing an existing layer

Digitalisasi

Tambah Fitur

lihat Digitizing an existing layer

Digitalisasi

Tambah Fitur

lihat Digitizing an existing layer

Digitalisasi

7.1. Bar Menu

Shortcut

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7.1.4 Tampilan Pilihan Menu

Shortcut

Referensi

Toolbar

Pan Peta

Navigasi Peta

Geser Peta untuk Menyeleksi

Navigasi Peta

Perbesar Perkecil Pilih →

Ctrl+-

Identifikasi Fitur Mengukur →

Ctrl+Shift+I

Perbesar semua

Navigasi Peta

Ctrl++ lihat Pilih dan lepas fitur

Navigasi Peta Atribut

lihat Mengukur

Atribut Atribut

kbd:Ctrl+Shift+F

Navigasi Peta

Perbesar ke lapisan Perbesar yang diseleksi

Navigasi Peta Navigasi Peta

Ctrl+J

Perbesaran Terakhir

Navigasi Peta

Perbesar Selanjutnya

Navigasi Peta

Perbesar Ukuran Aktual Dekorasi →

Navigasi Peta lihat Dekorasi

Informasi Peta

Atribut

Bookmark Baru

Ctrl+B

lihat Bookmark Spasial

Atribut

Lihat Bookmarks

Ctrl+Shift+B

lihat Bookmark Spasial

Atribut

Refresh

Ctrl+R

Navigasi Peta

7.1.5 Lapisan Pilihan Menu Baru → Lekatkan Lapisan dan Grup ...

Shortcut

Referensi lihat Creating new Vector layers lihat Proyek-proyek Nesting

Tambah Lapisan Vektor

kbd:Ctrl+Shift+V

lihat Pekerjaan dengan Data Vektor

Tambahkan Lapisan Raster

Ctrl+Shift+R

lihat Loading raster data in QGIS

Tambah Lapisan PostGIS

Ctrl+Shift+D

lihat PostGIS Layers

Tambahkan Lapisan SpatiaLite

Ctrl+Shift+L

lihat SpatiaLite Layers

Tambahkan Lapisan MSSQL Spasial

Ctrl+Shift+M

lihat label_mssql

Tambah Lapisan Oracle GeoRaster

lihat Oracle GeoRaster Plugin

Tambah Lapisan SQL Anywhere

Lihat Plugin SQL Anywhere

Tambah Lapisan WMS/WMTS

Ctrl+Shift+W

lihat WMS/WMTS Client

Tambah Lapisan WCS

lihat WCS Client

Tambah Lapisan WFS

lihat WFS and WFS-T Client

Tambahkan Lapisan Delimited Teks

lihat Menambahkan Lapisan Teks Delimited (Delimited Text Lay

Gaya Salin

lihat Style Menu

Gaya Tempel

lihat Style Menu

Lanjut ke h 26

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Tabel 7.1 – lanjutan dari halaman sebelumnya Shortcut Referensi

Pilihan Menu Buka Tabel Atribut

lihat Working with the Attribute Table

Toggle Mengedit

lihat Digitizing an existing layer

Simpan Lapisan diedit

lihat Digitizing an existing layer

Diedit Sekarang → Simpan Sebagai... Simpan terpilih sebagai berkas vektor... Buang Lapisan Atur CRS Lapisan Atur CRS proyek dari Lapisan Properti Query...

lihat Digitizing an existing layer Lihat Working with the Attribute Table Ctrl+D Ctrl+Shift+C

Pelabelan Tambahkan ke Overview

Ctrl+Shift+O

Tambahkan Semua ke Overview Menghapus Semua dari Overview Lihat Semua Lapisan

Ctrl+Shift+U

Sembunyikan Semua Lapisan

Ctrl+Shift+H

7.1.6 Pengaturan Pilihan Menu Panel → Toolbar → Toggle Mode Layar Penuh Proyek Properti ...

Shortcut

Referensi Lihat Panel dan Toolbar Lihat Panel dan Toolbar

Toolbar

Ctrl-F Ctrl+Shift+P

lihat Proyek lihat Custom Coordinate Reference System lihat vector_style_manager

Ubah CRS ... Pengelola Gaya... Konfigurasi shortcut ... Kustomisasi ... Opsi ... Opsi Snapping ...

lihat Penyesuaian (Customization) lihat Opsi

7.1.7 Plugin Pilihan Menu Kelola dan Pasang Plugin Konsol Python GRASS →

Shortcut

Referensi

Toolbar

lihat Mengelola Plugin lihat GRASS GIS Integration

GRASS

Saat memulai QGIS untuk pertama kali tidak semua inti plugin dimuat.

7.1. Bar Menu

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7.1.8 Vektor Pilihan Menu Rekaman Koordinat → Dxf2Shp → GPS → Open Street Map → Grafik Road → Query Spasial →

Shortcut

Referensi lihat Plugin Mengambil Koordinat lihat Plugin Pengonversi Dxf2Shp lihat GPS Plugin lihat Loading OpenStreetMap Vectors lihat Plugin Grafik Jalan lihat Plugin Spasial Query

Toolbar Vektor Vektor Vektor

Vektor

Saat memulai QGIS untuk pertama kali tidak semua inti plugin dimuat.

7.1.9 Raster Pilihan Menu Kalkulator Raster Georeferencer → Heatmap → Interpolasi → Statistik Zonal →

Shortcut

Referensi lihat Raster Calculator lihat Plugin Georeferencer lihat Heatmap Plugin lihat Plugin Interpolasi lihat Plugin Statistik Zonal

Toolbar Raster Raster Raster Raster

Saat memulai QGIS untuk pertama kali tidak semua inti plugin dimuat.

7.1.10 Basis data Pilihan Menu eVis → Spit →

Shortcut

Referensi lihat eVis Plugin lihat label_spit

Toolbar Basis data Basis data

Saat memulai QGIS untuk pertama kali tidak semua inti plugin dimuat.

7.1.11 Pengolahan Pilihan Menu

Shortcut

Referensi

Toolbar

Toolbox

lihat The toolbox

Toolbox

Grafis Modeler

lihat The graphical modeler lihat The history manager

Sejarah dan Log Opsi dan Konfigurasi

lihat Configuring the processing framework

Penampil hasil

lihat Configuring external applications

Perintah

Ctrl+Alt+M

lihat The SEXTANTE Commander

Saat memulai QGIS untuk pertama kali tidak semua inti plugin dimuat.

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7.1.12 Bantuan Pilihan Menu Konten Bantuan Apakah ini? Dokumentasi API Butuh dukungan ? |qg| Beranda

Shortcut

Referensi

Toolbar

F1

Bantuan

Shift+F1

Bantuan

Ctrl+H

Periksa versi |qg| Tentang Sponsor |qg| Harap dicatat bahwa untuk Linux item Menu Bar yang tercantum di atas adalah yang standar di window manager KDE. Di GNOME, menu Pengaturan memiliki isi yang berbeda dan item bisa ditemukan di sini: Properti Proyek Opsi Konfigurasi Shortcuts Pengelola Gaya

Proyek Edit Edit Edit

Modifikasi CRS Panel → Toolbar → Toggle Mode Layar Penuh Slider Skala Tile Pelacakan GPS

Edit Tampilan Tampilan Tampilan Tampilan Tampilan

7.2 Toolbar Toolbar menyediakan akses ke sebagian besar fungsi yang sama seperti menu, ditambah alat tambahan untuk berinteraksi dengan peta. Setiap item toolbar memiliki popup bantuan yang tersedia. Tahan tetikus anda ke atas item dan deskripsi singkat mengenai tujuan alat itu akan ditampilkan. Setiap menubar dipindah kesekitarnya sesuai dengan kebutuhan Anda. Selain itu setiap menubar dapat dimatikan menggunakan tombol kanan tetikus pada menu konteks Anda, arahkan tetikus ke toolbar (baca juga Panel dan Toolbar) Tip: Mengembalikan toolbar Jika Anda tidak sengaja telah menyembunyikan semua toolbar Anda, Anda dapat mengembalikannya dengan memilih menu opsi Pengaturan → Toolbar →. Jika toolbar menghilang di bawah OS Windows, tampaknya menjadi masalah di QGIS dari waktu ke waktu, Anda harus menghapus \HKEY_CURRENT_USER\Software\QGIS\qgis\UI\state di registry. Ketika Anda hidupkan ulang QGIS, kuncinya ditulis lagi secara standar, dan semua toolbar terlihat kembali.

7.3 Legenda Peta Area legenda peta merupakan daftar semua lapisan (layer) dalam proyek. Suatu lapisan (layer) dapat dipilih dan digeser ke atas atau kebawah pada legenda menjadi Z-ordering. Z-ordering berarti bahwa lapisan yang terdaftar di bagian atas legenda digambar lapisan bawahnya tercantum dalam legenda.

7.2. Toolbar

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Catatan: Perilaku ini dapat diganti dengan panel ‘urutan lapisan’. Lapisan di jendela legenda dapat dikelompokkan dalam grup. Ada dua cara untuk melakukannya: 1. Klik kanan di jendela legenda dan pilih Tambah Grup. Beri nama untuk grup tersebut dan tekan Enter. Sekarang klik pada lapisan (layer) yang ada dan geser ke dalam grup. 2. Pilih beberapa lapisan (layer), klik kanan pada jendela legenda dan pilih Grup Terpilih. Lapisan-lapisan yang dipilih secara otomatis akan menjadi satu grup baru. Untuk mengeluarkan lapisan dari grup, Anda bisa menggesernya keluar, atau klik kanan dan pilih Ubah jadi tingkat teratas. Grup dapat masuk kedalam grup lain. Kotak centang grup akan memunculkan atau menyembunyikan lapisan dalam grup dengan satu klik. Isi dari konteks menu tombol kanan tetikus tergantung pada item legenda yang dipilih lapisan (layer) raster atau Toggle mengedit tidak tersedia. Lihat bagian Digitizing and editing a GRASS vektor. Untuk lapisan vektor GRASS vector layer untuk informasi menyunting lapisan (layer) vektor GRASS.

Tombol kanan tetikus untuk lapisan raster • Perbesar lapisan extent • Perbesar Skala Terbaik (100%) • Peregangan Menggunakan Luas Terkini • Tampilkan di overview • Buang • Duplikat • Atur CRS Lapisan • Atur CRS Proyek dari Lapisan • Simpan sebagai ... • Properti • Ubah Nama • Gaya Salin • Tambah Grup Baru • Perlihatkan semua • Tutup semua • Pembaruan Pesanan Drawing Selain itu, menurut posisi dan seleksi lapisan (layer) • Ubah jadi item tingkat teratas • Grup dipilih Tombol kanan tetikus menu untuk lapisan vektor • Perbesar ke Lapisan Extent • Tampilkan di Overview • Buang • Duplikat • Atur CRS Lapisan • Atur CRS Proyek dari Lapisan • Buka Tabel Atribut

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• Toggle Mengedit (tidak tersedia untuk Lapisan GRASS) • Simpan Sebagai ... • Simpan Yang Diseleksi Sebagai • Saring • Tampilkan Fitur Hitung • Properti • Ubah Nama • Gaya Salin • Tambah Grup Baru • Perlihatkan semua • Tutup semua • Pembaruan Pesanan Drawing Selain itu, menurut posisi dan seleksi lapisan (layer) • Ubah jadi item tingkat teratas • Grup dipilih Tombol kanan tetikus menu untuk grup lapisan • Perbesar ke Grup • Buang • Atur Grup CRS • Ubah Nama • Tambah Grup Baru • Perlihatkan semua • Tutup semua • Pembaruan Pesanan Drawing Saat ini memungkinkan memilih lebih dari satu lapisan atau grup pada waktu yang sama dengan menekan tombol Ctrl sambil memilih lapisan dengan tombol kiri tetikus. Kemudian Anda dapat memindah semua lapisan terpilih ke dalam grup baru pada waktu yang sama. Anda juga dapat menghapus lebih dari satu Lapisan atau Grup sekaligus dengan memilih beberapa Lapisan (layer) dengan menekan tombol Ctrl dan setelah itu Ctrl+D. Dengan cara ini semua Lapisan atau Grup terpilih akan dibuang dari daftar lapisan.

7.3.1 Bekerja dengan Legenda urutan lapisan tersendiri Terdapat widget yang memungkinkan untuk mendefinisikan urutan legenda gambar independen. Anda dapat mengaktifkannya dari menu Pengaturan → Panel → Urutan Lapisan. Di sini menentukan urutan gambar dari lapisan dalam tampilan peta. Melakukan hal ini memungkinkan untuk mengurutkan lapisan Anda dalam urutan kepentingan, sebagai contoh, tapi masih menampilkan mereka dalam urutan yang benar (lihat figure_layer_order). Mengaktifkan kotak perilaku standar.

7.3. Legenda Peta

Kontrol urutan rendering bawah daftar lapisan akan menyebabkan kembali ke suatu

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Gambar 7.2: Mendefiniskan legenda urutan lapisan tersendiri

7.4 Tampilan Peta Ini “business end” dari QGIS - peta tampil di area ini! Peta yang ditampilkan dalam jendela ini tergantung pada lapisan vektor dan raster yang telah Anda pilih (lihat bagian informasi lebih lanjut tentang cara untuk memuat lapisan). Tampilan peta dapat digeser (mengalihkan fokus tampilan peta untuk daerah lain) dan memperbesar atau memperkecilnya. Berbagai operasi lainnya dapat dilakukan pada peta seperti yang dijelaskan dalam deskripsi toolbar di atas. Tampilan peta dan legenda terikat erat satu sama lain - peta dalam tampilan mencerminkan perubahan yang Anda buat di daerah legenda. Tip: Perbesar peta dengan tetikus Anda dapat menggunakan tetikus untuk memperbesar dan memperkecil peta. Tempatkan kursor tetikus di dalam area peta dan roll roda depan (jauh dari Anda) untuk memperbesar dan belakang (ke arah Anda) untuk memperkecil. Posisi kursor tetikus adalah pusat di mana perubahan terjadi. Anda dapat menyesuaikan perilaku pembesaran roda tetikus menggunakan menu Alat Peta dalam menu Pengaturan → Opsi. Tip: Menggeser peta dengan tombol panah dan spasi bar Anda dapat menggunakan tombol panah untuk menggeser peta. empatkan kursor tetikus dalam area peta dan klik panah kanan untuk menggeser ke Timur, panah kiri untuk menggeser ke Barat, panah atas untuk menggeser ke Utara dan pana bawah untuk menggeser ke Selatan. Anda juga dapat menggeser peta dengan menggunakan bar spasi atau klik pada tetikus: hanya menggerakkan tetikus bersamaan menekan bar spasi atau klik tetikus.

7.5 Status Bar Bar status melihatkan posisi kursor Anda dalam koordinat peta (misal meter atau derajat desimal) sesuai dengan titik kursor tetikus bergerak pada tampilan peta. Di sebelah kiri tampilan koordinat di bar status adalah tombol kecil yang akan beralih antara menampilkan posisi koordinat atau menampilkan luasan peta saat Anda menggeser dan memperbesar/memperkecil tampilan peta. Sebelah tampilan koordinat Anda menemukan tampilan skala. Itu menunjukkan skala dari tampilan peta. Jika Anda memperbesar atau memperkecil QGIS berisi skala saat ini. Ada pemilih skala yang memungkinkan Anda untuk memilih skala standar dari 1:500 sampai 1:1000000.

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Suatu perkembangan (progres) bar di status bar menunjukkan kemajuan (progres) render karena setiap lapisan yang diubah di tampilan peta. Dalam beberapa kasus, seperti pengumpulan statistik di lapisan raster, progress bar akan menunjukkan status panjangnya operasi. Jika ada plugin baru atau pembaruan plugin tersedia, Anda akan melihat pesan sebelah kiri dari bar status. Di sisi kanan status bar adalah kotak centang kecil yang dapat digunakan untuk lapisan sementara yang diberikan ke tampilan peta (lihat Bagian Rendering). Ikon

menghentikan proses rendering peta sekarang.

Sebelah kanan dari fungsi render, Anda akan menemukan kode EPSG dari CRS proyek sekarang dan ikon proyektor. Mengklik ini akan membuka properti proyeksi untuk proyek saat ini. Tip: Menghitung skala koreksi dari kanvas peta Anda Saat Anda memulai QGIS, derajat merupakan unit standar, dan QGIS memberitahu bahwa setiap koordinat pada lapisan Anda dalam derajat. Untuk mengubah nilai skala, Anda juga dapat mengubahnya ke satuan meter secara manual di tab Umum dalam Pengaturan → Proyek Properti atau Anda bisa memilih Coordinate Reference System CRS status (CRS) proyek dengan klik ikon di bagian kanan bawah dari status bar. Dalam kasus terakhir, unit ditetapkan untuk menentukan proyeksi proyek, misalnya ‘+unit=m’.

7.5. Status Bar

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8.1 Fitur Identifikasi Fitur identifikasi memungkinkan berinteraksi dengan kanvas peta untuk mendapatkan atribut data pada sebuah jendela pop-up. Fitus identifikasi menggunakan Tampilan → Identifikasi Fitur atau Ctrl+Shift+I, atau klik ikon pada

Identifikasi Fitur

toolbar.

Jika Anda klik beberapa fitur, poop-up ini akan mendaftar semua data atribut dari semua fitur. Item pertama adalah jumlah item dalam daftar hasil diikuti dengan nama lapisan. Maka anak pertama akan menjadi nama sebuah kolom dengan nilainya. Akhirnya semua informasi dari fitur tersebut akan ditampilkan. Jendela ini dapat disesuaikan untuk menampilkan kolom kustom namun secara default akan menampilkan tiga jenis informasi: • Aksi-aksi: Aksi-aksi ditambahkan untuk mengidentifikasi fitur windows. Ketika mengklik pada aksi label, aksi akan berjalan. Secara default hanya satu tindakan ditambahkan untuk meihat form fitur untuk mengedit. • Derived: informasi mereka dihitung atau berasal dari informasi lainnya. Anda bisa menemukan koordinat diklik, koordinat X dan Y, area di unit dan parameter peta dalam unit peta untuk poligon, panjang unit peta untuk garis dan id fitur. • Data atribut: Daftar kolom atribut dari data

Gambar 8.1: Dialog identifikasi fitur

(Gnome)

Di bagian bawah dari jendela, Anda memiliki lima ikon: •

Expand tree

•

Collapse tree

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•

Default behaviour

•

Salin atribut

•

Print selected HTML response

Fitur selebihnya dapat ditemukan dalam tampilan menu dengan klik kanan tetikus pada suatu tempat dengan respon pohon. Menu ini memungkinkan untuk: • Lihat form fitur • Perbesar ke fitur • Salin fitur: salin semua fitur geometri dan atribut; • Salin nilai atribut: hanya menyalin nilai dari atribut Anda klik; • Salin atribut fitur: hanya menyalin atribut • Bersihkan hasil: hasil di jendela telah dihapus • Bersihkan highlight: fitur highlight pada peta telah dihapus • Highlight semua • Highlight lapisan • Properti lapisa: buka jendel properti lapisan • Perluas (expand) semua • Runtuh (collapse) semua

8.2 Shortcut Papanketik QGIS menyediakan standar shortcut papan ketik untuk banyak fitur. Anda menemukannya di Bagian Bar Menu. Selain itu di menu opsi Pengaturan → Konfigurasi Shortcut memungkinkan merubah standar shortcut papanketik dan menambah shortcut papanketik baru ke fitur QGIS.

Gambar 8.2: Tentukan pilihan shortcut

(Gnome)

Konfigurasi sederhana. Hanya pilih fitur dari daftar dan klik pada [Ubah], [Atur none] atau [Atur Standar]. Setelah Anda telah menemukan konfigurasi, Anda dapat menyimpannya sebagai berkas XML dan muat pada instalasi QGIS lain.

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8.3 Konteks Bantuan Saat Anda membutuhkan bantuan dengan topik yang spesifik, Anda dapat mengakses konteks bantuan melalui tombol Bantuan tersedia disebagian besar dialog - harap dicatat bahwa plugin pihak ketiga dapat mengarah ke halaman web khusus.

8.4 Rendering Secara standar, QGIS membuat semua lapisan terlihat setiap kali kanvas peta di-refresh. Peristiwa yang memicu refresh kanvas peta meliputi: • Menambahkan lapisan (layer) • Menggeser atau memperbesar • Mengukur jendela QGIS • Merubah visitabilitas dari lapisan (layer) QGIS memungkinkan Anda mengontrol proses rendering dalam beberapa cara.

8.4.1 Scale Dependent Rendering Skala render memungkinkan Anda untuk menentukan skaa minimum dan skala maksimum di mana lapisan akan terlihat. Untuk mengatur skala render bergantung, buka dialog Properti dengan mengklik-dobel pada lapisan di Gunakan skala dependent rendering untuk mengaktifkan legenda. Pada tab Umum klik pada kotak centang fitur yang mengatur nilai maskimum dan minimum skala. Anda dapat menentukan nilai skala dengan terlebih dahulu perbesar ke tingkat yang ingin Anda gunakan dan mencatat nilai skala pada status bar QGIS.

8.4.2 Mengontrol Rendering Peta Rendering peta dapat dikontrol dengan mengikuti petunjuk: Menunda Rendering Untuk menunda rendering, klik kotak centang

Render di sudut bawah kanan dari status bar. Ketika kotak

centang Render tidak diaktifkan, QGIS tidak menggambar ulang kanvas dalam menanggapi setiap kejadian yang telah diuraikan dalam Bagian Rendering. Contoh ketika Anda mungkin ingin menunda render meliputi: • Tambahkan beberapa lapisan dan simbol sebelum menggambar • Tambahkan satu atau lebih lapisan dan atur skala ketergantungan sebelum menggambar • Tambahkan satu atau lebih lapisan dan perbesar ke tampilan yang spesifik sebelum menggambar • Kombinasi dari yang ada di atas Aktifkan kotak centang peta.

8.3. Konteks Bantuan

Render mengaktifkan rendering dan dan menyebabkan refresh langsung dari kanvas

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Pengaturan Lapisan Tambah Opsi Anda dapat mengatur pilihan untuk selalu memuat lapisan baru tanpa menggambar mereka. Ini berarti lapisan akan ditambahkan ke peta, namun visibilitas kotak centang dalam legenda akan dicentang secara default. Untuk mengatur opsi ini, pilih menu opsi Pengaturan → Opsi → dan klik pada menu Rendering. Hapus tanda centang Secara standar lapisan baru ditambahkan ke peta selalu ditampilkan. Setiap lapisan ditambahkan ke peta akan tidak terlihat secara standar. Opsi lain di menu Pengaturan → Opsi → Rendering kotak centang Aktifkan buffer. Ini memberikan kinerja grafis yang lebih baik pada kemungkinan kehilangan biaya untuk membatalkan rendering dan menggambar fitur tambahan. Jika tidak dicentang, Anda dapat mengatur ‘Jumlah fitur untuk menarik sebelum memperbarui tampilan’, selain itu tidak aktif. Akhirnya Anda bisa mengaktifkan kotak centang bar ulang.

Gunakan render caching mungkin untuk mempercepat gam-

Menghentikan Rendering Untuk menghentikan penggambaran peta, tekan tombol ESC. Ini akan menghentikan refresh kanvas peta dan menghentikan proses penggambaran peta. Hal ini mungkin membutuhkan waktu selama menekan ESC dan penggambaran peta terhenti. Catatan: Saat ini tidak memungkikan untuk menghentikan rendering - ini dinonaktifkan di port qt4 karena masalah antarmuka pengguna (UI) dan konflik (crash).

Memperbarui tampilan peta sebelum rendering Anda dapat mengatur pilihan untuk memperbarui tampilan peta sebagai fitur. Secara standar, QGIS tidak menampilkan semua fitur untuk lapisan sampai seluruh lapisan telah dirender.Untuk memperbarui tampilan seperti fitur dibaca dari datastore, pilih opsi menu Pengaturan → Opsi klik pada menu Rendering. Mengatur jumlah fitur untuk nilai yang sesuai untuk memperbarui tampilan selama rendering. Menetapkan nilai 0 menonaktifkan pembaruan selama menggambar (ini adalah default). Menetapkan nilai terlalu rendah akan menghasilkan kinerja yang buruk pada kanvas peta terus diperbarui selama pembacaan fitur. Nilai yang disarankan untuk memulai adalah 500. Mempengarui Kualitas Rendering Untuk mempengaruhi kualitas dari peta Anda memiliki 2 opsi. Pilih opsi menu Pengaturan → Opsi klik pada menu Rendering dan pilih atau tidak kotak centang berikut. •

Membuat garis tampil kurang baik dengan mengorbankan beberapa kinerja menggambar

•

Memperbaiki masalah isi poligon

8.5 Mengukur Mengukur peta dalam proyeksi sistem koordinat (misal UTM) dan data belum terproyeksi. Jika peta dimuat didefinisikan dengan sistem koordinat geografis (lintang/bujur), hasil dari garis atau daerah pengukuran akan salah. Untuk memperbaiki ini, Anda perlu mengatur peta sesuai sistem koordinat (lihat Bagian Working with Projections). Semua modul pengukuran juga menggunakan pengaturan snapping dari modul digitalisasi. Hal ini berguna, jika Anda ingin mengukur garis atau area di lapisan vektor. Untuk memilih alat ukur, klik di

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8.5.1 Mengukur panjang, area dan sudut Mengukur Garis

: QGIS mampu mengukur jarak nyata antar poin yang diberikan sesuai dengan ellipsoid yang didefinisikan. Untuk mengonfigurasinya, pilih menu opsi Pengaturan → Opsi, klik tab Peralatan Peta dan pilih ellipsoid yang tepat. Di sana Anda juga dapat mendefinisikan warna karet gelang (rubberband) dan satuan pengukuran pilihan Anda (meter atau feet) dan satuan sudut (derajat, radian dan gon). Kemudian memungkinkan Anda untuk mengklik titik pada peta. Setiap panjang-segmen serta total muncul dalam jendela-ukuran. Untuk menghentikan pengukuran klik tombol tetikus sebelah kanan.

Gambar 8.3: Mengukur Panjang

(Gnome)

Mengukur Area

: Area juga dapat diukur. Pada jendela mengukur muncul ukuran daerah akumulasi. Selain itu, alat ukur akan mengambil (snap) ke lapisan yang sedang dipilih, asalkan lapisan yang memiliki toleransi yang ditetapkan. (Lihat Bagian Setting the Snapping Tolerance and Search Radius). Jadi jika Anda ingin mengukur persis sepanjang fitur garis, atau sekitar fitur poligon, pertama kali atur toleransi snap, kemudian pilih lapisan. Sekarang, ketika menggunakan alat ukur, setiap klik tetikus (dalam pengaturan toleransi) akan merekam (snap) ke lapisan itu.

Gambar 8.4: Mengukur Area

(Gnome)

Mengukur Sudut

: Anda juga bisa mengukur sudut. Kursor menjadi cross-shaped. Klik untuk menggambar segmen pertama dari sudut yang ingin diukur, kemudian memindahkan kursor untuk menggambar sudut yang diinginkan. Alat ukur akan ditampilkan dalam dialog pop-up.

Gambar 8.5: Mengukur Sudut

(Gnome)

8.5.2 Pilih dan lepas fitur Toolbar QGIS menyediakan beberapa alat untuk memilih fitur dalam kanvas peta. Untuk memilih satu atau beberapa fitur klik pada

8.5. Mengukur

dan pilih perangkat Anda:

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•

Pilih Fitur Tunggal

•

Pilih Fitur dari Rectangle

•

Pilih Fitur dari Poligon

•

Pilih Fitur dari Freehand

•

Pilih Fitur dari Radius

Untuk melepas semua fitur yang dipilih klik di

Lepas fitur dari semua lapisan

.

8.6 Dekorasi Dekorasi dari QGIS termask Grid, Label Hak Cipta, Panah Utara, dan Bar Skala. Mereka digunakan untuk ‘dekorasi’ peta dengan menambahkan elemen peta.

8.6.1 Kisi (Grid) Grid

memungkinkan untuk menambahkan koordinat kisi (grid) dan koordinat anotasi untuk kanvas peta.

Gambar 8.6: Dialog Kisi (Grid) 1. Pilih dari menu Tampilan → Decorasi → Kisi. Mulai dialog (lihat figure_decorations_1). 2. Aktifkan kotak centang Aktifkan Kisi dan menetapkan definisi kisi (grid) sesuai dengan lapisan yang dimuat dalam kanvas peta. 3. Aktifkan kotak centang Gambar anotasi dan menetapkan definisi anotasi sesuai dengan lapisan yang dimuat dalam kanvas peta. 4. Klik [Terapkan] untuk memeriksa, jika terlihat seperti yang diharapkan. 5. Klik [OK] untuk menutup dialog.

8.6.2 Label Hak Cipta Label Hak Cipta

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menambahkan label hak cipta menggunakan teks untuk peta.

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Gambar 8.7: Dialog Hak Cipta 1. Pilih dari menu Tampilan → Dekorasi → Label hak Cipta. (lihat figure_decorations_2). 2. Masukkan teks yang Anda ingin tempatkan di peta. Anda bisa menggunakan HTML seperti dalam contoh 3. Pilih penempatan label dari Penempatan ‘Kanan Bawah’ kotak drop-down 4. Pastikan kotak centang telah ditandai/aktifkan Aktifkan Label Hak Cipta 5. Klik [OK] Dalam contoh di atas (default) QGIS menempatkan simbol hak cipta diikuti dengan tanggal di bagian bawah sudut kanan dari kanvas peta.

8.6.3 Panah Utara Panah Utara

menempatkan panah utara sederhana di kanvas peta. Saat ini hanya ada satu gaya yang tersedia. Anda dapat mengatur sudut panah atau membiarkan QGIS mengatur arah secara otomatis. Jika Anda memilih untuk membiarkan QGIS menentukan arah, itu membuat QGIS menebak yang terbaik bagaimana panah harus berorientasi. Untuk penempatan panah, Anda memiliki empat pilihan, sesuai dengan empat penjuru kanvas peta.

Gambar 8.8: Dialog Panah Utara

8.6.4 Bar Skala

Skala Bar

menambahkan bar skala sederhana untuk kanvas peta. Anda mengontrol gaya dan penempatan, serta pelabelan bar. QGIS hanya mendukung menampilkan skala dalam satuan yang sama dengan kerangka peta Anda. Jadi jika satuan lapisan Anda dalam meter, Anda tidak dapat membuat skala bar dalam kaki (feet). Demikian juga jika Anda menggunakan derajat desimal, Anda tidak dapat membuat skala bar untuk menampilkan jarak dalam meter.

8.6. Dekorasi

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Gambar 8.9: Dialog Bar Skala Menambahkan bar skala: 1. Pilih dari menu Tampilan → Dekorasi → Skala Bar (lihat figure_decorations_4) 2. Pilih penempatan dari daftar drop-down Penempatan ‘Kiri Bawah’ 3. Pilih gaya dari daftar Gaya bar Skala ‘Tick Down’ 4. Pilih warna bar warna bar ‘black’ atau gunakan hitam warna default 5. Atur ukuran bar dan labelnya Ukuran bar ‘30 degrees’ 6. Pastikan kotak centang sudah aktif

Aktifkan skala bar

7. Opsional memilih secara otomatis snap ke angka bulat ketika kanvas diubah ukurannya snap to round number on resize

Automatically

8. Klik [OK] Tip: Pengaturan Dekorasi Saat Anda menyimpan sebuah proyek .qgs, setiap perubahan yang Anda buat pada Kisi (Grid), Panah Utara, Skala Bar dan Hak Cipta akan disimpan dalam proyek dan dikembalikan pada saat Anda memuat proyek.

8.7 Peralatan Anotasi Anotasi Teks Peralatan dalam toolbar atribut memberikan kemungkinan untuk menempatkan teks diformat dalam balon pada kanvas Peta QGIS. Gunakan alat Anotasi Teks dan klik kedalam kanvas peta.

Dobel klik pada item membuka dialog dengan berbagai pilihan. Ada editor teks untuk memasukkan teks yang diformat dan pengaturan item lain. Misalnya ada pilihan memiliki item ditempatkan pada posisi peta (ditampilkan dengan simbol penanda) atau memiliki item pada posisi layar (tidak berhubungan dengan peta). Item ini bisa dipindahkan dengan posisi peta (geser penanda peta) atau hanya dengan memindahkan balon. Ikon adalah bagian dari tema GIS, dan digunakan secara default dalam tema-tema lain juga. Alat

Pindah Anotasi

memungkinkan memindah anotas pada kanvas peta.

8.7.1 Anotasi HTML Anotasi Html dalam toolbar atribut memberikan kemungkinan untuk menempatkan isi berkas HTML dalam Alat balon pada kanvas Peta QGIS. Gunakan alat Anotasi Html dan klik kedalam kanvas peta dan menambahkan path

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Gambar 8.10: Dialog teks anotasi ke berkas html ke dalam dialog.

8.7.2 Anotasi SVG Anotasi SVG dalam toolbar atribut memberikan kemungkinan untuk menempatkan simbol SVG dalam balon Alat pada kanvas Peta QGIS. Gunakan alat Anotasi SVG dan klik kedalam kanvas peta dan menambahkan path ke berkas SVG ke dalam dialog.

8.7.3 Form anotasi Form Anotasi Selain itu Anda juga dapat membuat form anotasi Anda sendiri. Alat ini berguna untuk menampilkan atribut dari lapisan vektor dalam form desainer qt disesuaikan (lihat figure_custom_annotation). Hal ini mirip dengan form desainer alat Identifikasi fitur, tetapi ditampilkan dalam item anotasi. Lihat juga blog QGIS http://blog.qgis.org/node/143 untuk informasi lebih lanjut.

Catatan: Jika Anda menekan Ctrl+T sementara alat Anotasi aktif (anotasi bergerak, anotasi teks, form anotasi), visibilitas item yang terbalik.

8.8 Bookmark Spasial Bookmark spasial memungkinkan Anda untuk “bookmark” lokasi geografis dan kembali ke spasial ini suatu saat nanti.

8.8.1 Membuat Bookmark Membuat Bookmark 1. Perbesar atau geser ke interes area. 2. Pilih menu opsi Tampilan → Bookmark Baru atau tekan Ctrl-B.

8.8. Bookmark Spasial

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Gambar 8.11: Disesuaikan form anotasi bentuk desainer qt 3. Masukkan nama deskripsi dari bookmark (batas 255 karakter). 4. Tekan Enter untuk menambahkan bookmark atau [Delete] untuk menghapus bookmark. Catatan Anda bisa memiliki bookmark banyak dengan satu nama.

8.8.2 Bekerja dengan Bookmark Menggunakan atau mengelola bookmark, pilih menu opsi Tampilan → Tampilkan Bookmark.

8.8.3 Perbesar ke Bookmark Dari dialog Geospasial Bookmark, pilih bookmark yang diinginkan dengan mengkliknya, kemudian klik [Perbesar]. Anda juga bisa memperbesar ke bookmark dengan dobel-klik padanya.

8.8.4 Menghapus Bookmark Menghapus bookmark dari dialog Geospasial Bookmark, klik padanya dan kemudian klik [Hapus]. Konfirmasi Anda pilih dengan klik [Ya] atau batal menghapus dengan klik [Tidak]..

8.9 Proyek-proyek Nesting Jika Anda ingin menanamkan (embed) isi dari berkas proyek lain kedalam proyek Anda, Anda bisa memilih Lapisan → Tanam Lapisan dan Grup.

8.9.1 Menanam (Embedding) lapisan Mengkuti dialog memungkinkan Anda untuk menanam (embed) lapisan dari proyek-proyek lain: 1. Tekan 44

untuk mencari proyek lain dari dataset Alaska. Bab 8. Peralatan Umum

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2. Pilih berkas proyek grassland. Anda bisa melihat konten dari proyek (lihat figure_embed_dialog). 3. Tekan Ctrl dan klik pada lapisan grassland dan wilayah. Lapisan akan ditanam dalam legenda peta dan tampilan peta sekarang.

Gambar 8.12: Pilih lapisan-lapisan dan grup-grup untuk ditanam (embed) Sementara lapisan-lapisan yang ditanam (embedded) adalah bisa diedit Anda tidak bisa merubah properti seperti gaya dan pelabelan. Menghapus lapisan-lapisan ditanam (embdded) Klik-kanan pada lapisan yang ditanam (embedded) dan pilih

Hapus

.

8.10 Menambahkan Lapisan Teks Delimited (Delimited Text Layer) Fungsi ini memungkinkan Anda memuat berkas teks delimited sebagai lapisan di QGIS. Pengaturan berikut perlu didefinisikan: 1. Format Berkas biasanya CSV (comma separated values). Jika delimiter lain digunakan, aktifkan tombol custom delimiter‘dan jika setiap baris dalam file dibagi menggunakan ekspresi reguler, silakan aktifkan tombol |radiobuttonon| :guilabel:‘Regular expression delimiter. 2. Sebagai berkas teks Opsi Rekam biasanya menyediakan baris header dipisahkan kolom nama. Ini biasanya baris pertama dalam berkas teks. Jika tidak ada baris header yang tersedia, nonaktfikan kotak centang rekaman pertama adalah kolom nama. Dan jika baris header bukan baris pertama dari berkas teks, tentukan jumlah baris header untuk dibuang. 3. Sebagai Opsi Lapangan Anda dapat memotong spasi kolom leading dan trailing dari mengaktifkan kotak centang

Trim fields. Anda bisa

tukan bahwa

Discard empty fields di setiap rekaman dan Anda juga bisa menen-

Sebagai pemisah desimal adalah koma. Jika tidak, akan menjadi titik.

4. Sebagai Definisi Geometri berkas teks khas menyediakan Koordinate Poin. Ini berarti harus ada kolom ‘X’ dan ‘Y’ dengan nilai koordinat. Jika berkas teks menyediakan kolom Well Known Text, maka harus ada kolom ‘WKT’ dengan informasi geometri untuk byek poin, garis atau poligon. Kolom ini dapat memiliki nama apapun. Jika tabel atribut mendefinisikan tidak geometri. Koordinat x dan y harus spesifik sebagai angka. Sistem koordinat tidak penting. Jika didefinisikan dalam derajat/menit/detik, aktfikan kota centang

Koordinat DMS.

5. Sebagai Pengaturan Lapisan Anda bisa mengaktifkan

Gunakan Indeks Spasial untuk meningkatkan

kinerja dari menampilkan dan memilih spasial fitur. Anda bisa mendefinsikan dan

Gunakan Indeks Subset

Watch file untuk melihat perubahan berkas dengan aplikasi lain, sementara QGIS berjalan.

Sebagai contoh sebuah berkas teks yang valid kita mengimpor berkas data elevasi titik elevp.csv dengan contoh dataset QGIS (Lihat Bagian Contoh data):

8.10. Menambahkan Lapisan Teks Delimited (Delimited Text Layer)

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X;Y;ELEV -300120;7689960;13 -654360;7562040;52 1640;7512840;3 [...]

Beberapa item dari catatan tentang berkas teks adalah: 1. Contoh berkas teks menggunakan ; (semicolon) sebagai delimiter. Beberapa karakter bisa digunakan untuk kolom delimit. 2. Baris pertama adalah baris header. Ini berisi X, Y dan ELEV. 3. Tidak ada kutipan (") digunakan untuk bidang teks delimit 4. Koordinat X diisi dalam bidang X. 5. Koordinat Y diisi dalam bidang Y.

8.10.1 Menggunakan fungsi Tambah Lapisan Teks Delimited Klik ikon toolbar di toolbar Kelola Lapisan membuka dialog Membuat Lapisan dari Berkas Teks Delimited seperti yang tampil dalam figure_delimited_text_1.

Gambar 8.13: Dialog Teks Delimited Pertama pilih berkas (seperti qgis_sample_data/csv/elevp.csv) untuk impor dengan mengklik pada tombol [Penjelajah]. Sekali berkas dipilih, upaya QGIS untuk mem-parsing berkas menggunakan delimiter yang terakhir digunakan, dalam kasus ini titikkoma (;). Untuk mem-parsing berkas dengan benar, Ini penting untuk memilih delimiter yang benar. Mengubah delimiter penggunaan tab \t (ini adalah ekspresi reguler untuk karakter tab.). Setelah berkas diuraikan, buat sebuah Definsi Geometri Koordinat Poin dan pilih kolom X dan Y dari daftar. Akhirnya masukkan nama lapisan (seperti elevp) seperti dalam figure_delimited_text_1 . Untuk menambahkan lapisan ke dalam peta, klik [OK]. Berkas teks delimited yang sekarang berperilaku seperti halnya lapisan peta lainnya di QGIS.

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BAB 9

Konfigurasi QGIS

QGIS dapat dikonfigurasi melalui menu Pengaturan. Pilih diantara Panel, Toolbar, Properti Proyek, Opsi dan Penyesuaian.

9.1 Panel dan Toolbar Dalam menu Panel→ Anda bisa mengatifkan dan menonaktfikan widget QGIS. Menu Toolbar→ memberikan kemungkinan mengaktfikan dan menonatifkan ikon grup di toolbar QGIS (lihat figure_panels_toolbars).

Gambar 9.1: Menu Panel dan Toolbar Tip: Mengaktifkan Tinjauan QGIS Di QGIS Anda dapat menggunakan panel gambaran yang menyediakan tampilan lapisan tingkat penuh yang ditambahkan ke dalamnya. Hal ini dapat dipilih di bawah menu Tampilan → Panel. Dalam pandangan persegi panjang yang menunjukkan tingkat peta saat ini. Hal ini memungkinkan Anda dengan cepat menentukan area peta yang sedang Anda lihat. Perhatikan bahwa label tidak diberikan ke gambaran peta bahkan jika lapisan dalam gambaran peta telah diatur untuk pelabelan. Jika Anda klik dan tarik persegi panjang merah dalam gambaran yang menunjukkan gambaran Anda saat ini, tampilan utama peta akan memperbarui. Tip: Tampilkan Pesan Log Log Pesan dalam menu Settings → Ini memungkinkan untuk melacak pesan QGIS. Anda bisa mengaktifkan Panel dan ikuti pesan di dalam tab Umum dan Plugin selama memuat dan operasi. 47

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9.2 Properti Proyek Di properti jendela dari proyek Proyek → Proyek Properti atau opsi spesifik proyek Mereka termasuk:

Proyek → Proyek Properti Anda mengatur

• Di dalam menu Umum judul proyek, seleksi dan warna latar, satuan lapisan, presisi, dan pilihan untuk menyimpan path relatif terhadap lapisan yang dapat ditentukan. Jika transformasi CRS aktif Anda dapat memilih ellipsoid untuk perhitungan jarak. Anda dapat menentukan satuan kanvas (hanya digunakan ketika transformasi CRS dinonaktifkan) dan ketepatan desimal untuk digunakan. Anda juga dapat menentukan daftar skala proyek, yang menimpa skala yang telah ditentukan global. • Menu CRS memungkinkan Anda untuk memilih Coordinat Reference System untuk proyek ini, dan memungkinkan proyeksi ulang on-the-fly lapisan raster dan lapisan vektor ketika menampilkan lapisan dari CRS yang berbeda. • Dengan menu ketiga Identifikasi lapisan Anda atur (atau nonaktif) lapisan akan merespon alat mengidentifikasi. (Lihat paragraf peralatan Peta dari bagian Opsi untuk mengaktifkan identifikasi atau lapisan multi.) • Menu Gaya Standar memungkinkan Anda mengontrol bagaimana lapisan baru akan digambar ketika mereka tidak memiliki gaya .qml yang ditentukan. Anda juga dapat mengatur standar tingkat transparansi untuk lapisan baru dan apakah simbol harus memiliki warna acak kepada mereka. • Tab OWS Server memungkinkan untuk menentukan informasi tentang Server WMS dan kapabilitas WFS QGIS, Pada Tingkat dan Pembatasan CRS. • Menu Macros untuk membuat modul Python, disimpan ke berkas proyek.qgs akan dimuat dan memiliki spesifik fungsi yang berjalan pada proyek berikut: openProject(), saveProject() dan closeProject().

Gambar 9.2: Pengaturan Macro di QGIS

9.3 Opsi Beberapa pilihan dasar untuk QGIS dapat dipilih menggunakan dialog Opsi. Pilih menu opsi Pengaturan → Opsi. Menu di mana Anda dapat mengoptimalkan opsi Anda:

9.3.1 Menu Umum Aplikasi

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• Pilih Gaya (QGIS diperlukan restart) tique’ dan ‘Cleanlux’ ( ). • Definisikan Ikon tema

dan pilih diantara ‘Oxygen’,’Windows’,’Motif’,’CDE’, ‘Plas-

. Sekarang hanya ‘default’.

• Definisikan Ukuran Ikon

. QT default dan font user-defined.

• Definisikan Font. Pilih antara

• Ubah Timeout for timed messages or dialogs •

Sembunyikan layar splash saat startup

•

Tampilkan Petunjuk saat startup

•

Judul tebal kotak grup

•

QGIS-styled kotak grup

•

Gunakan dialog pemilih warna live-updating

.

Berkas proyek • Buka proyek pada peluncuran ‘khusus’ menggunakan •

(memilih antara ‘Baru’. ‘Terbaru’ dan ‘Khusus’. Ketika memilih

untuk menentukan proyek)

Buat proyek baru dari proyek default. Anda memiliki kemungkinan untuk menekan Atur proyek sekarang sebagai default atau pada Reset default. Anda dapat menelusuri melalui berkas-berkas dan menentukan direktori dimana Anda menemukan pengguna-ditetapkan proyek template Anda. Akan ada sebuah entri di Project → Baru dari Template jika Anda pertama kali mengaktifkan proyek default dan kemudian simpan proyek dalam folder proyek template.

Buat proyek baru dari

•

Prompt untuk menyimpan proyek dan sumber data perubahan bila diperlukan

•

Peringatkan ketika membuka berkas proyek yang disimpan dengan versi lama dari |qg|

• Aktifkan macro

. Opsi ini diciptakan untuk menangani macro yang ditulis untuk melakukan aksi

pada proyek. Anda bisa memilih diantara ‘Tidak pernah’, ‘Bertanya’, ‘Hanya untuk sesi ini’ dan ‘Selalu (tidak direkomendasikan)’.

9.3.2 Menu Sistem Lingkungan Sistem lingkungan variabel saat ini dapat dilihat dan banyak dikonfigurasi dalam menu Lingkungan (lihat figure_environment_variables). Hal ini berguna untuk platform, seperti Mac, di mana aplikasi GUI tidak selalu mewarisi lingkungan shell pengguna. Ini juga berguna untuk pengaturan / melihat lingkungan variabel untuk mengatur alat eksternal yang dikendalikan oleh pengolahan toolbox, seperti GRASS; dan, untuk menyalakan keluaran debugging untuk bagian tertentu dari kode sumber. •

Gunakan penyesuaian variabel (dibutuhkan restart - termasuk pemisah). Anda bisa Tambah dan Hapus variabel. Ligkungan variabel sekarang → ditampilkan dibawah dan ini memungkinkan hanya variabel spesifik-QGIS.

Tampilkan

Plugin path • Tambah atau Hapus Path(s) untuk mencari tambahan C++ librari Plugin

9.3. Opsi

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Gambar 9.3: Sistem lingkungan variabel dalam QGIS

9.3.3 Menu sumber data Atribut dan tabel fitur • •

Buka tabel atribut di dock window (dibutuhkan restart QGIS) Salin

geometri

di

representasi

WKT

dari

tabel

Ketika

atribut.

menggunakan

Salin baris yang dipilih ke papan klip

dari menu Tabel atribut kemudian ini memiliki hasil yang juga koordinat titik atau simpul disalin ke papan klip. • Perilaku tabel atribut . Ada tiga kemungkinan: ‘Tampilkan semua fitur’, ‘Tampilkan fitur dipilih’ dan ‘Tampilkan fitur terlihat pada peta’ • Tabel atribut baris cache . Baris cache ini memungkinkan untuk menyimpan baris x atribut terakhir dimuat sehingga proses tabel atribut akan lebih cepat. Cache akan dihapus ketika menutup tabel atribut. • Representasi untuk nilai NULL Here you can define a value for data fields containing a NULL value. Di sini Anda dapat menentukan nilai untuk bidang data yang berisi nilai NULL. Menangani sumber data • Pindai item yang valid di dock Browser isi berkas’.

. Anda dapat memilih antara ‘Periksa ekstensi’ dan ‘Periksa

• Pindai isi dari berkas yang dikompresi (.zip) di browser dock ful’ memungkinkan.

. ‘Tidak’, ‘Pindai dasar’ and ‘Pindai

• Konfirmasi subl-lapisan raster saat membuka. Beberapa raster mendukung sublapisan - mereka disebut subdataset di GDAL. Contohnya adalah berkas netcdf - jika ada banyak variabel netcdf, GDAL melihat setiap variabel sebagai sub dataset. Pilihan ini untuk mengontrol bagaimana menangani sub-lapisan ketika sebuah berkas dengan sub-lapisan dibuka. Anda memiliki pilihan berikut: – ‘Selalu’: selalu bertanya (jika ada sub-lapisan yang ada) – ‘Jika diperlukan’: menanyakan apakah lapisan tidak memiliki band, namun memiliki sub-lapisan – ‘Tidak Pernah’: tidak pernah meminta, tidak akan memuat apa-apa – ‘Muat semua’: tidak pernah meminta, tetapi memuat semua sub-lapisan • •

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Abaikan deklarasi encoding shapefile. Jika shapefile punya pengkodean informasi ini akan diabaikan oleh QGIS. Tambahkan lapisan PostGIS dengan klik ganda dan pilih dalam mode diperpanjang

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•

Tambahkan lapisan Oracle with dobel klik dan pilih dalam mode diperpanjang

9.3.4 Menu Rendering Kualitas rendering •

Membuat garis tampil kurang bagus dengan mengorbankan beberapa kinerja menggambar

•

Memperbaiki masalah poligon salah diisi

Raster-raster • dengan RGB band seleksi Anda bisa menetapkan nomor dari band Merah, Hijau dan Biru. Peningkatan kontras • Band abu-abu tunggal . Sebuah band abu-abu tunggal dapat memiliki ‘Tidak ada peregangan’, ‘Lakukan peregangan untuk MinMax’, ‘Peregangan dan Klip ke MinMax’ dan juga ‘Clip ke MinMax’ . ‘Tidak ada peregangan’, ‘Lakukan peregangan untuk MinMax’, ‘Pere• band multi warna (byte/band) gangan dan Klip ke MinMax’ dan juga ‘Clip ke MinMax’ • band multi warna (>byte/band) . ‘Tidak ada peregangan’, ‘Lakukan peregangan untuk MinMax’, ‘Peregangan dan Klip ke MinMax’ dan juga ‘Clip ke MinMax’ • Batas (minimum/maksimum) standar deviasi’

. ‘Kumulatif jumlah potong pixel’, ‘Minimum/Maksimum’, ‘Berarti +/-

• Kumulatif batas jumlah potong pixel • Standar deviasi multiplier Debugging • Tampilkan peristiwa ini dalam panel Log Pesan (di bawah tab render):

Refresh kanvas peta

9.3.5 Menu Kanvas dan Legenda Standar penampilan peta (diganti oleh proyek properti) • Tetapkan Seleksi warna dan Warna latar. Legenda lapisan • Dobel klik pada legenda klik.

. Anda dapat ‘Buka properti lapisan’ atau ‘Buka atribut tabel’ dengan dobel

• mengikuti Gaya item legenda –

Nama lapisan kapital

–

Nama lapisan tebal

–

Nama grup tebal

–

Tampilkan klasifikasi nama atribut

–

Buat ikon raster (mungkin lambat)

–

Tambah lapisan baru ke grup sekarang atau yang dipilih

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9.3.6 Menu perangkat Peta Identifikasi •

Buka hasil identifikasi di dock window (dibutuhkan restart QGIS)

• Pengaturan Mode menentukan lapisan akan ditampilkan oleh alat Identifikasi. Dengan beralih ke ‘Top down’ atau ‘Top down, stop at first’ dan bukan ‘Current layer’ atribut untuk semua lapisan diidentifikasi (lihat bagian properti Proyek di bawah: Proyek untuk mengatur lapisan yang dapat diidentifikasi) akan ditampilkan dalam alat Identifikasi. •

Buka form fitur, jika fitur tunggal teridentifikasi

• Tentukan Cari radius untuk mengidentifikasi dan menampilkan petunjuk peta sebagai persentase dari lebar peta. Alat pengukuran • Tentukan Warna Rubberband untuk peralatan pengukuran • Tentukan Tempat desimal •

Perlu satuan dasar

• Satuan pengukuran dipilih • Satuan sudut yang dipilih

(‘meter’ atau ‘kaki’ (‘Sudut’, ‘Radian’ atau ‘Gon’)

Menggeser dan memperbesar • Tentukan Aksi roda tetikus ada’)

(‘Perbesar’, ‘Perbesar dan pusat’, ‘Perbesar pada kursor tetikus’, ‘Tidak

• Tentukan Faktor pembesaran untuk roda tetikus Skala yang ditentukan Di sini Anda menemukan daftar skala yang telah ditentukan. Dengan tombol ‘+’ dan ‘-‘ Anda dapat menambahkan atau menghapus skala individu Anda.

9.3.7 Menu Digitalisasi Membuat fitur •

Menekan atribut jendela pop-up setelah setiap fitur dibuat

•

Gunakan kembali nilai atribut terakhir yang dimasukkan

• Validasi geometris. Mengedit garis/poligon kompleks dengan banyak node menyebabkan render sangat lambat. Hal ini karena prosedur standar validasi di QGIS dapat menghabiskan banyak waktu. Untuk mempercepat rendering itu dengan memilih validasi geometri GEOS (mulai dari GEOS 3.3) atau untuk mematikannya. Validasi geometri GEOS jauh lebih cepat, tetapi merugikan adalah bahwa hanya masalah geometri pertama akan dilaporkan. Rubberband • Tentukan Rubberband Lebar garis dan Warna garis Snapping •

Buka opsi mengambil di dock window (dibutuhkan restart QGIS)

• Tentukan Mode standar snap

(‘Simpul’, ‘Segmen’, ‘Simpul dan Segmen’, ‘Mati’)

• Tentukan Default toleransi snapping dalam satuan peta atau pixel • Tentukan Cari radius untuk suntingan simpul dalam satuan peta atau pixel

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Penanda simpul •

Tampilkan penanda hanya untk fitur yang dipilih

• Tentukan simpul Gaya Penanda

(‘Palang’ (standar), ‘Lingkaran semi transparan’ atau ‘Tidak ada’)

• Tentukan simpul Ukuran Penanda Alat ofset kurva Kurva Ofset 3 pilihan berikutnya mengacu pada alat di Advanced digitizing. Melalui berbagai pengaturan, ini mungkin untuk mempengaruhi bentuk garis ofset. Pilihan-pilhan ini dari GEOS 3.3.

• Gabung gaya untuk ofset kurva • Segmen Quadrant untuk ofset kurva • Batas Miter untuk ofset kurva

9.3.8 Menu GDAL GDAL adalah data pertukaran librari untuk berkas raster. Dalam tab ini Anda dapat Edit opsi membuat dan Edit Opsi Pyramid dari format raster. Menentukan driver GDAL yang akan digunakan untuk format raster seperti dalam beberapa kasus lebih dari satu driver GDAL tersedia.

9.3.9 Menu CRS CRS standar untuk proyek baru •

Secara otomatis mengaktifkan ‘on the fly’ proyeksi ulang jika lapisan memiliki beda CRS

•

Aktfikan proyeksi ulang on the fly secara standar

• Pilih sebuah CRS dan Selalui mulai proyek baru dengan CRS ini CRS untuk lapisan baru Daerah ini memungkinkan untuk menentukan tindakan, ketika sebuah lapisan baru dibuat, atau ketika lapisan tanpa CRS dimuat. •

Konfirmasi CRS

•

Gunakan CRS proyek

•

Gunakan standar CRS ditampilkan dibawah ini

9.3.10 Tab Lokal •

Timpah sistem lokal dan Lokal gunakan sebagai pengganti

• Informasi tentang sistem lokal aktif

9.3.11 Tab Jaringan Umum • Tentukan WMS cari alamat, default http://geopole.org/wms/search?search=\%1\&type=rss • Tentukan Timeout untuk permintaan jaringan (ms) - default 60000 • Tentukan Standar periode ekspirasi untuk WMSC/WMTS (jam) - default 24

9.3. Opsi

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Gambar 9.4: Pengaturan-proxy di QGIS Pengaturan cache Tentukan Direktori dan Ukuran untuk cache. •

Gunakan proxy untuk akses web dan tentukan ‘Host’, ‘Port’, ‘Pengguna’, and ‘Kata Sandi’.

• Atur Tipe Proxy

sesuai dengan kebutuhan Anda.

– Proxy Standar: Proxy ditentukan berdasarkan aplikasi pengaturan menggunakan proxy – Socks5Proxy: Proxy generik untuk setiap jenis koneksi. Mendukung TCP, UDP, mengikat ke port (koneksi masuk) dan otentikasi. – HttpProxy: Menggunakan perintah “CONNECT”, mendukung hanya koneksi TCP; mendukung otentikasi. – HttpCachingProxy: Menggunakan perintah normal HTTP, itu hanya berguna dalam konteks permintaan HTTP – FtpCachingProxy: Menggunakan proxy FTP, itu hanya berguna dalam konteks permintaan FTP Tidak termasuk beberapa URL dapat ditambahkan ke kotak teks di bawah pengaturan-proxy (lihat Figure_Network_Tab). Jika Anda membutuhkan informasi lebih rinci tentang pengaturan-proxy yang berbeda, silakan lihat panduan QTlibrari-dokumentasi di http://doc.trolltech.com/4.5/qnetworkproxy.html#ProxyType-enum. Tip: Menggunakan Proxi Menggunakan proxi kadang-kadang bisa rumit. Hal ini berguna untuk ‘coba dan eror’ jenis proxi di atas dan memeriksa apakah mereka berhasil dalam kasus Anda. Anda dapat mengubah pilihan sesuai dengan kebutuhan Anda. Beberapa perubahan mungkin memerlukan restart QGIS sebelum berjalan efektif. •

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Pengaturan tersimpan di berkas teks: $HOME/.config/QGIS/qgis.conf

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•

Anda dapat menemukan pengaturan Anda di $HOME/Library/Preferences/org.qgis.qgis.plist

•

pengaturan terkirim ke registri: HKEY\CURRENT_USER\Software\QGIS\qgis

9.4 Penyesuaian (Customization) Alat penyesuaian memungkinkan Anda mengaktifkan (dan nonaktif) hampir setiap elemen dalam antar muka QGIS. Hal ini bisa sangat berguna jika Anda memiliki banyak plugin yang dipasang bahwa Anda tidak pernah menggunakan dan mengisi layar Anda.

Gambar 9.5: Dialog penyesuaian

Penyesuaian QGIS dibagi menjadi lima kelompok. Dalam

Menu Anda dapat menyembunyikan entri dalam

Menu bar. Dalam Panel Anda dapat menemukan Panel jendela. Jendela Panel adalah aplikasi yang dapat dimulai dan digunakan sebagai mengambang, jendela tingkat-atas atau tertanam ke jendela utama QGIS sebagai widget. (lihat juga Panel dan Toolbar). Dalam fitur

Status Bar seperti informasi koordinat dapat dinonak-

tifkan. Dalam Toolbars Anda dapat mengaktifkan (non aktif) ikon toolbar QGIS dan mengaktifkan (non aktif) dialog serta tombol mereka.

Widgets Anda dapat

Beralih ke penangkapan widget dalam aplikasi utama Dengan Anda dapat mengklik elemen dalam QGIS Anda ingin menyembunyikan dan menemukan entri yang sesuai (lihat figure_customization). Anda juga dapat menyimpan berbagai setup yang berbeda untuk kasus penggunaan yang berbeda juga. Sebelum perubahan diterapkan, Anda harus me-restart QGIS.

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Working with Projections

QGIS allows users to define a global and project-wide CRS (Coordinate Reference System) for layers without a pre-defined CRS. It also allows the user to define custom coordinate reference systems and supports on-the-fly (OTF) projection of vector and raster layers. All these features allow the user to display layers with different CRS and have them overlay properly.

10.1 Overview of Projection Support QGIS has support for approximately 2,700 known CRS. Definitions for each of these CRS are stored in a SQLite database that is installed with QGIS. Normally you do not need to manipulate the database directly. In fact, doing so may cause projection support to fail. Custom CRS are stored in a user database. See Section Custom Coordinate Reference System for information on managing your custom coordinate reference systems. The CRS available in QGIS are based on those defined by the European Petroleum Search Group (EPSG) and the Institut Geographique National de France (IGNF) and are largely abstracted from the spatial reference tables used in GDAL. EPSG identifiers are present in the database and can be used to specify a CRS in QGIS. In order to use OTF projection, your data must contain information about its coordinate reference system or you have to define a global, layer or project-wide CRS. For PostGIS layers QGIS uses the spatial reference identifier that was specified when the layer was created. For data supported by OGR, QGIS relies on the presence of a recognized means of specifying the CRS. In the case of shapefiles, this means a file containing the Well Known Text (WKT) specification of the CRS. This projection file has the same base name as the shapefile and a prj extension. For example, a shapefile named alaska.shp would have a corresponding projection file named alaska.prj. Whenever you select a new CRS, the used layer units will automatically be changed in the General menu of the Project Properties dialog under the Project (Gnome, OSX) or Settings (KDE, Windows) menu.

10.2 Global Projection Specification QGIS starts each new project using the global default projection. The global default CRS is EPSG:4326 - WGS 84 (proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs) and comes predefined in QGIS. This default can be changed using the [Select...] button in the first section, used to defining the Default Coordinate Reference System to use when starting new projects, as shown in figure_projection_1. This choice will be saved for use in subsequent QGIS sessions. When you use layers that do not have a CRS, you need to define how QGIS responds to these layers. This can be done globally or project-wide in the CRS menu under Settings → Options. The options shown in figure_projection_1 are: •

Prompt for CRS

•

Use project CRS

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Gambar 10.1: CRS tab in the QGIS Options Dialog •

Use default CRS displayed below

If you want to define the coordinate reference system for a certain layer without CRS information, you can also do that in the General menu of the raster (see General Menu) and vector (see General Menu) properties dialog. If your layer already has a CRS defined, it will be displayed as shown in Vector Layer Properties Dialog . Tip: CRS in the Map Legend Right-clicking on a layer in the Map Legend (Section Legenda Peta) provides two CRS short cuts. Set layer CRS takes you directly to the Coordinate Reference System Selector dialog (see figure_projection_2). Set project CRS from Layer redefines the project CRS using the layer’s CRS

10.3 Define On The Fly (OTF) Reprojection QGIS supports OTF reprojection for both raster and vector data. However, OTF is not activated by default. To use OTF projection, you must activate the

Enable on the fly CRS transformation checkbox in the CRS menu of the

Project Properties dialog. There are three ways to achieve this end: 1. Select

Project Properties from the Project (Gnome, OSX) or Settings (KDE, Windows) menu.

2. Click on the

CRS status

icon in the lower right-hand corner of the statusbar.

3. Turn OTF on by default, by selecting the CRS tab of the Options dialog and selecting reprojection by default.

Enable ‘on the fly’

If you have already loaded a layer, and want to enable OTF projection, the best practice is to open the Coordinate Reference System menu of the Project Properties dialog, select a CRS, and activate the transformation checkbox. The to the CRS shown next to the icon.

CRS status

Enable on the fly CRS

icon will no longer be greyed-out and all layers will be OTF projected

The Coordinate Reference System menu of the Project Properties dialog contains five important components as shown in Figure_projection_2 and described below. 1. Enable on the fly CRS transformation - this checkbox is used to enable or disable OTF projection. When off, each layer is drawn using the coordinates as read from the data source and the components described below are inactive. When on, the coordinates in each layer are projected to the coordinate reference system defined for the map canvas.

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Gambar 10.2: Project Properties Dialog 2. Coordinate Reference System - this is a list of all CRS supported by QGIS, including Geographic, Projected and Custom coordinate reference systems. To define a CRS, select it from the list by expanding the appropriate node and selecting the CRS. The active CRS is preselected. 3. Proj4 text - this is the CRS string used by the Proj4 projection engine. This text is read-only and provided for informational purposes. 4. Filter - if you know the EPSG code, the identifier or the name for a Coordinate Reference System, you can use the search feature to find it. Enter the EPSG code, the identifier or the name. 5. Recently used CRS - if you have certain CRS that you frequently use in your everyday GIS work, these will be displayed in the table at the bottom of the Projection Dialog. Click on one of these buttons to select the associated CRS. Tip: Project Properties Dialog If you open the Project Properties dialog from the Project (Gnome, OSX) or Settings (KDE, Windows) menu, you must click on the CRS menu to view the Coordinate Reference System settings. The

CRS status

icon will also automatically bring the CRS menu to the front.

10.4 Custom Coordinate Reference System If QGIS does not provide the coordinate reference system you need, you can define a custom CRS. To define a Custom CRS from the Settings menu. Custom CRS are stored in your QGIS user database. In CRS, select addition to your custom CRS, this database also contains your spatial bookmarks and other custom data. Defining a custom CRS in QGIS requires a good understanding of the Proj.4 projection library. To begin, refer to the Cartographic Projection Procedures for the UNIX Environment - A User’s Manual by Gerald I. Evenden, U.S. Geological Survey Open-File Report 90-284, 1990 (available at ftp://ftp.remotesensing.org/proj/OF90-284.pdf ).

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Gambar 10.3: Custom CRS Dialog This manual describes the use of the proj.4 and related command line utilities. The cartographic parameters used with proj.4 are described in the user manual and are the same as those used by QGIS. The Custom Coordinate Reference System Definition dialog requires only two parameters to define a user CRS: 1. a descriptive name and 2. the cartographic parameters in PROJ.4 format. To create a new CRS, click the

New

you can save your CRS by clicking the

button and enter a descriptive name and the CRS parameters. After that Save

button.

Note that the Parameters must begin with a +proj=-block, to represent the new coordinate reference system. You can test your CRS parameters to see if they give sane results by clicking on the [Calculate] button inside the Test block and pasting your CRS parameters into the Parameters field. Then enter known WGS 84 latitude and longitude values in North and East fields respectively. Click on [Calculate] and compare the results with the known values in your coordinate reference system.

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QGIS Peramban

Peramban QGIS adalah panel di QGIS yang memungkinkan Anda dengan mudah menavigasi dalam basisdata Anda. Anda memiliki akses ke berkas-berkas vektor umum (seperti berkas ESRI shapefile atau MapInfo), basisdata (seperti PostGIS, Oracle, Spatialite atau MSSQL Spatial) dan koneksi WMS/WFS. Anda juga bisa melihat data GRASS Anda (untuk mendapatkan data ke QGIS lihat GRASS GIS Integration)

Gambar 11.1: Penjelajah QGIS merupakan aplikasi standalone Menggunakan penjelajah QGIS untuk menampilkan data Anda. Fungsi geser dan taruh membuatnya mudah untuk menempatkan data Anda ke tampilan peta dan legenda peta. 1. Mengaktifkan penjelajah QGIS. Klik-kanan pada toolbar dan klik → Panel.

Peramban atau pilih dari Pengaturan

2. Geser panel kedalam jendela legenda 3. Klik pada tab Peramban 4. Jelajahi dalam basisdata Anda dan pilih folder shapefile dari qgis_sample_data. 5. Tekan tombol Shift dan klik pada airports.shp dan alaska.shp . 6. Tekan tombol kiri tetikus kemudian geser dan tempatkan berkas ke dalam kanvas peta. 7. Klik-kanan pada lapisan dan pilih Atur CRS proyek dari lapisan. Untuk informasi lebih lanjut lihat Working with Projections. 8. Klik pada

Perbesar Full

agar lapisan-lapisan terlihat.

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Ada peramban kedua yang tersedia di Settings → Panel. Fungsi tambahan seperti Saring Berkas

Tambah Lapisan Terpilih

dan

fungsi disisipkan.

1. Mengaktifkan penjelajah QGIS kedua: Klik-kanan pada toolbar dan klik

Peramban (2) .

2. Geser panel kedalam jendela legenda 3. Arahkan ke tab Peramban (2) dan temukan shapefile di dalam sistem berkas Anda. 4. Pilih sebuah berkas dengan tombol kiri tetikus. Kini Anda bisa menggunakan ikon Gunakan ikon untuk dapat bekerja dengan berkas QGIS tanpa banyak usaha.

Tambah Lapisan Terpilih

.

QGIS otomatis terlihat untuk Coordinate Reference System (CRS) dan perbesar ke batas lapisan jika Anda bekerja di sebuah proyek kosong QGIS. Jika sudah ada berkas dalam proyek Anda, berkas hanya akan ditambahkan dan dalam kasus itu memiliki tingkat yang sama dan CRS akan divisualisasikan. Jika berkas ini telah mendapat CRS lain dan lapisan Anda terlebih dahulu klik kanan pada lapisan dan pilih Atur CRS Proyek dari Lapisan. Kemudian pilih Perbesar ke Batas Lapisan. Saring Berkas bekerja pada level direktori. Jelajahi folder dimana Anda ingin menyaring berkas-berkas Fungsi dan memberikan kata pencarian atau wildcard. Penjelajah hanya menampilkan nama berkas yang sesuai dari data lain tidak akan ditampilkan kemudian.

Ini juga mungkin untuk menjalankan peramban QGIS sebagai aplikasi mandiri. Mulai Peramban QGIS • •

ketik di dalam “qbrowser” di perintah prompt. Memulai peramban QGIS menggunakan menu Start atau shortcut dekstop, atau dobel klik pada berkas proyek QGIS.

• Peramban

QGIS juga tersedia di fodler Aplikasi Anda.

Dalam figure_browser_standalone_metadata Anda bisa melihat ditingkatkan fungsi peramban QGIS. Tab Param menyediakan detail dari koneksi dataset seperti PostGIS atau MSSQL Spatial. Tab Metadata berisi informasi umum tentang berkas (lihat Metadata Menu). Dengan tab Preview Anda bisa melihat-lihat di berkas Anda tanpa mengimpor mereka ke proyek QGIS Anda. Ini juga mungkin untuk melihat atribut berkas Anda dalam tab Atribut

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Pekerjaan dengan Data Vektor

12.1 Supported Data Formats QGIS uses the OGR library to read and write vector data formats including ESRI Shapefiles, MapInfo, Microstation file formats and many more. GRASS vector, PostGIS, MSSQL Spatial and Oracle Spatial support is supplied by native QGIS data providers. Vector data can also be loaded in read mode from zip and gzip archives into QGIS. At the date of this document, 69 vector formats are supported by the OGR library (see OGR-SOFTWARE-SUITE Literatur dan Referensi Web). The complete list of supported vector data formats by the OGR library (see OGRSOFTWARE-SUITE Literatur dan Referensi Web) is available at http://www.gdal.org/ogr/ogr_formats.html. Catatan: Not all of the listed formats may work in QGIS for various reasons. For example, some require external commercial libraries or the GDAL/OGR installation of your OS was not build to support the format you want to use. Only those formats that have been well tested will appear in the list of file types when loading a vector into QGIS. Other untested formats can be loaded by selecting *.*. Working with GRASS vector data is described in Section GRASS GIS Integration. This section describes how to work with several common formats: ESRI Shapefiles, PostGIS layers, SpatiaLite layers, OpenStreetMap vectors etc. Many of the features available in QGIS work the same, regardless of the vector data source. This is by design and includes the identify, select, labeling and attributes functions.

12.1.1 ESRI Shapefiles The standard vector file format used in QGIS is the ESRI Shapefile. Support is provided by the OGR Simple Feature Library ( http://www.gdal.org/ogr/ ). A shapefile actually consists of several files. The following three are required: 1. .shp file containing the feature geometries. 2. .dbf file containing the attributes in dBase format. 3. .shx index file. Shapefiles also can include a file with a .prj suffix, which contains the projection information. While it is very useful to have a projection file, it is not mandatory. A shapefile dataset can contain additional files. For further details see the ESRI technical specification at: http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf. Loading a Shapefile Add Vector Layer To load a shapefile, start QGIS and click on the toolbar button or simply type Ctrl+Shift+V. This will bring up a new window (see figure_vector_1).

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Gambar 12.1: Add Vector Layer Dialog From the available options check File. Click on button [Browse]. That will bring up a standard open file dialog (see figure_vector_2) which allows you to navigate the file system and load a shapefile or other supported data source. The selection box Filter

allows you to preselect some OGR supported file formats.

You can also select the Encoding type for the shapefile if desired.

Gambar 12.2: Open an OGR Supported Vector Layer Dialog Selecting a shapefile from the list and clicking [Open] loads it into QGIS. Figure_vector_3 shows QGIS after loading the alaska.shp file. Tip: Layer Colors When you add a layer to the map, it is assigned a random color. When adding more than one layer at a time, different colors are assigned to each layer. Once loaded, you can zoom around the shapefile using the map navigation tools. To change the style of a layer, open the Layer Properties dialog by double clicking on the layer name or by right-clicking on the name in the legend and choosing Properties from the popup menu. See Section Style Menu for more information on setting symbology of vector layers. Tip: Load layer and project from mounted external drives on OS X On OS X, portable drives that are mounted besides the primary hard drive do not show up under File → Open Project as expected. We are working on a more OSX-native open/save dialog to fix this. As a workaround you can

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Gambar 12.3: QGIS with Shapefile of Alaska loaded type ‘/Volumes’ in the File name box and press return. Then you can navigate to external drives and network mounts.

Improving Performance for Shapefiles To improve the performance of drawing a shapefile, you can create a spatial index. A spatial index will improve the speed of both zooming and panning. Spatial indexes used by QGIS have a .qix extension. Use these steps to create the index: • Load a shapefile, clicking on the

Add Vector Layer

toolbar button or type Ctrl+Shift+V.

• Open the Layer Properties dialog by double-clicking on the shapefile name in the legend or by right-clicking and choosing Properties from the popup menu. • In the tab General click the [Create Spatial Index] button. Problem loading a shape .prj file If you load a shapefile with .prj file and QGIS is not able to read the coordinate reference system from that file, you have to define the proper projection manually within the General tab of the Layer Properties dialog of the layer by clicking the [Specify...] button. This is due to the fact, that .prj files often do not provide the complete projection parameters, as used in QGIS and listed in the CRS dialog. For that reason, if you create a new shapefile with QGIS, two different projection files are created. A .prj file with limited projection parameters, compatible with ESRI software, and a .qpj file, providing the complete parameters of the used CRS. Whenever QGIS finds a .qpj file, it will be used instead of the .prj.

12.1.2 Loading a MapInfo Layer To load a MapInfo layer, click on the file type filter Filter

Add Vector Layer

toolbar button or type Ctrl+Shift+V, change the

: to ‘Mapinfo File [OGR]’ and select the MapInfo layer you want to load.

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12.1.3 Loading an ArcInfo Binary Coverage To load an ArcInfo binary coverage, click on the

Add Vector Layer

toolbar button or press Ctrl+Shift+V

Directory. Change to Filter to open the Add Vector Layer dialog. Select Navigate to the directory that contains the coverage files and select it.

to ‘Arc/Info Binary Coverage’.

Similarly, you can load directory based vector files in the UK National Transfer Format as well as the raw TIGER Format of the US Census Bureau.

12.1.4 Loading OpenStreetMap Vectors QGIS integrates Openstreetmap import as a core functionnality. • To connect to the OSM server and download data, open the menu Vector → Openstreetmap → Load data. You can skip this step if you already got a .osm XML file using josm or overpass or any other source. • The menu Vector → Openstreetmap → Import topology from an XML file will convert your .osm file into a spatialite database, and create a db connection. • The menu Vector → Openstreetmap → Export topology to Spatialite then allows you to open the database connection, select the type of data you want (points, lines, or polygons) and choose tags to import. This creates a spatialite geometry layer that you can then add to your project by clicking on the toolbar button or by selecting the SpatiaLite Layers.

Add SpatiaLite Layer

Add SpatiaLite Layer... option from the Layer menu, see Section

12.1.5 PostGIS Layers PostGIS layers are stored in a PostgreSQL database. The advantages of PostGIS are the spatial indexing, filtering and query capabilities it provides. Using PostGIS, vector functions such as select and identify work more accurately than with OGR layers in QGIS. Creating a stored Connection The first time you use a PostGIS data source, you must create a connection to the PostgreSQL database that Add PostGIS Layer contains the data. Begin by clicking on the Add PostGIS toolbar button, selecting the Layer... option from the Layer menu or typing Ctrl+Shift+D. You can also open the Add Vector Layer dialog and select Database. The Add PostGIS Table(s) dialog will be displayed. To access the connection manager, click on the [New] button to display the Create a New PostGIS Connection dialog. The parameters required for a connection are:

• Name: A name for this connection. Can be the same as Database • Service: Service parameter to be used alternatively to hostname/port (and potentially database). This can be defined in pg_service.conf • Host: Name of the database host. This must be a resolvable host name the same as would be used to open a telnet connection or ping the host. If the database is on the same computer as QGIS, simply enter ‘localhost’ here. • Port: Port number the PostgreSQL database server listens on. The default port is 5432. • Database: Name of the database. • SSL mode: How the SSL connection will be negotiated with the server. Note that massive speedups in PostGIS layer rendering can be achieved by disabling SSL in the connection editor. Following options are available: – disable: only try an unencrypted SSL connection 66

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– allow: try a non-SSL connection, if that fails, try an SSL connection – prefer (the default): try an SSL connection, if that fails, try a non-SSL connection; – require: only try an SSL connection. • Username: User name used to login to the database. • Password: Password used with Username to connect to the database. Optional you can activate following checkboxes: •

Save Username

•

Save Password

•

Only look in the geometry_columns table

•

Don’t resolve type of unrestricted columns (GEOMETRY)

•

Only look in the ‘public’ schema

•

Also list tables with no geometry

•

Use estimated table metadata

Once all parameters and options are set, you can test the connection by clicking on the [Test Connect] button. Tip: QGIS User Settings and Security Depending on your computing environment, storing passwords in your QGIS settings may be a security risk. Your customized settings for QGIS are stored based on the operating system: •

, the settings are stored in your home directory in .qgis2/.

•

, the settings are stored in the registry.

Loading a PostGIS Layer Once you have one or more connections defined, you can load layers from the PostgreSQL database. Of course this requires having data in PostgreSQL. See Section Importing Data into PostgreSQL for a discussion on importing data into the database. To load a layer from PostGIS, perform the following steps: • If the Add PostGIS layers dialog is not already open, selecting the Layer menu or typing Ctrl+Shift+D opens the dialog.

Add PostGIS Layer... option from the

• Choose the connection from the drop-down list and click [Connect]. • Select or unselect

Also list tables with no geometry

• Optionally use some Search Options to define which features to load from the layer or use the [Build query] button to start the Query builder dialog. • Find the layer(s) you wish to add in the list of available layers. • Select it by clicking on it. You can select multiple layers by holding down the Shift key while clicking. See Section Query Builder for information on using the PostgreSQL Query Builder to further define the layer. • Click on the [Add] button to add the layer to the map.

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Tip: PostGIS Layers Normally a PostGIS layer is defined by an entry in the geometry_columns table. From version 0.9.0 on, QGIS can load layers that do not have an entry in the geometry_columns table. This includes both tables and views. Defining a spatial view provides a powerful means to visualize your data. Refer to your PostgreSQL manual for information on creating views.

Some details about PostgreSQL layers This section contains some details on how QGIS accesses PostgreSQL layers. Most of the time QGIS should simply provide you with a list of database tables that can be loaded, and load them on request. However, if you have trouble loading a PostgreSQL table into QGIS, the information below may help you understand any QGIS messages and give you direction on changing the PostgreSQL table or view definition to allow QGIS to load it. QGIS requires that PostgreSQL layers contain a column that can be used as a unique key for the layer. For tables this usually means that the table needs a primary key, or a column with a unique constraint on it. In QGIS, this column needs to be of type int4 (an integer of size 4 bytes). Alternatively the ctid column can be used as primary key. If a table lacks these items, the oid column will be used instead. Performance will be improved if the column is indexed (note that primary keys are automatically indexed in PostgreSQL). If the PostgreSQL layer is a view, the same requirement exists, but views do not have primary keys or columns with unique constraints on them. You have to define a primary key field (has to be integer) in the QGIS dialog before you can load the view. If a suitable column cannot does not exist in the view, QGIS will not load the layer. If this occurs, the solution is to alter the view so that it does include a suitable column (a type of integer and either a primary key or with a unique constraint, preferably indexed). QGIS offers a checkbox Select at id that is activated by default. This option gets the ids without the attributes which is faster in most cases. It can make sense to disable this option when you use expensive views.

12.1.6 Importing Data into PostgreSQL Data can be imported into PostgreSQL/PostGIS using several tools, such as the SPIT plugin or the command line tools shp2pgsql or ogr2ogr. DB Manager DB Manager . It can be used to load shapefiles and other data formats and QGIS comes with a core plugin named includes support for schemas. See Section Plugin Pengelola DB for more information.

shp2pgsql PostGIS includes an utility called shp2pgsql that can be used to import shapefiles into a PostGIS enabled database. For example, to import a shapefile named lakes.shp into a PostgreSQL database named gis_data, use the following command: shp2pgsql -s 2964 lakes.shp lakes_new | psql gis_data

This creates a new layer named lakes_new in the gis_data database. The new layer will have a spatial reference identifier (SRID) of 2964. See Section Working with Projections for more information on spatial reference systems and projections. Tip: Exporting datasets from PostGIS Like the import-tool shp2pgsql there is also a tool to export PostGIS-datasets as shapefiles: pgsql2shp. This is shipped within your PostGIS distribution.

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ogr2ogr Beside shp2pgsql and DB Manager there is another tool for feeding geodata in PostGIS: ogr2ogr. This is part of your GDAL installation. To import a shapefile into PostGIS, do the following: ogr2ogr -f "PostgreSQL" PG:"dbname=postgis host=myhost.de user=postgres \ password=topsecret" alaska.shp

This will import the shapefile alaska.shp into the PostGIS-database postgis using the user postgres with the password topsecret on host server myhost.de. Note that OGR must be built with PostgreSQL to support PostGIS. You can see this by typing ogrinfo --formats | grep -i post

If you like to use PostgreSQL’s COPY -command instead of the default INSERT INTO method you can export the following environment-variable (at least available on

and

):

export PG_USE_COPY=YES

ogr2ogr does not create spatial indexes like shp2pgsl does. You need to create them manually using the normal SQL-command CREATE INDEX afterwards as an extra step (as described in the next section Improving Performance). Improving Performance Retrieving features from a PostgreSQL database can be time consuming, especially over a network. You can improve the drawing performance of PostgreSQL layers by ensuring that a PostGIS spatial index exists on each layer in the database. PostGIS supports creation of a GiST (Generalized Search Tree) index to speed up spatial searches of the data (GiST index information is taken from the PostGIS documentation available at http://postgis.refractions.net). The syntax for creating a GiST index is: CREATE INDEX [indexname] ON [tablename] USING GIST ( [geometryfield] GIST_GEOMETRY_OPS );

Note that for large tables, creating the index can take a long time. Once the index is created, you should perform a VACUUM ANALYZE. See the PostGIS documentation (POSTGIS-PROJECT Literatur dan Referensi Web) for more information. The following is an example of creating a GiST index: gsherman@madison:~/current$ psql gis_data Welcome to psql 8.3.0, the PostgreSQL interactive terminal. Type:

\copyright for distribution terms \h for help with SQL commands \? for help with psql commands \g or terminate with semicolon to execute query \q to quit

gis_data=# CREATE INDEX sidx_alaska_lakes ON alaska_lakes gis_data-# USING GIST (the_geom GIST_GEOMETRY_OPS); CREATE INDEX gis_data=# VACUUM ANALYZE alaska_lakes; VACUUM gis_data=# \q gsherman@madison:~/current$

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12.1.7 Vector layers crossing 180° longitude Many GIS packages don’t wrap vector maps, with a geographic reference system (lat/lon), crossing the 180 degrees longitude line (http://postgis.refractions.net/documentation/manual-1.4/ST_Shift_Longitude.html). As result, if we open such map in QGIS, we will see two far, distinct locations, that should show near each other. In Figure_vector_4 the tiny point on the far left of the map canvas (Chatham Islands), should be within the grid, right of New Zealand main islands.

Gambar 12.4: Map in lat/lon crossing the 180° longitude line A workaround is to transform the longitude values using PostGIS and the ST_Shift_Longitude function This function reads every point/vertex in every component of every feature in a geometry, and if the longitude coordinate is < 0° adds 360° to it. The result would be a 0° - 360° version of the data to be plotted in a 180° centric map.

Gambar 12.5: Crossing 180° longitude applying the ST_Shift_Longitude function

Usage • Import data to PostGIS (Importing Data into PostgreSQL) using for example the DB Manager plugin. • Use the PostGIS command line interface to issue the following command (this is an example where “TABLE” is the actual name of your PostGIS table) gis_data=# update TABLE set the_geom=ST_Shift_Longitude(the_geom); • If everything went right you should receive a confirmation about the number of features that were updated, then you’ll be able to load the map and see the difference (Figure_vector_5)

12.1.8 SpatiaLite Layers The first time you load data from a SpatiaLite database, begin by clicking on the button or by selecting the 70

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This will bring up a window, which will allow you to either connect to a SpatiaLite database already known to QGIS, which you can choose from the dropdown menu or to define a new connection to a new database. To define a new connection, click on [New] and use the file browser to point to your SpatiaLite database, which is a file with a .sqlite extension. If you want to save a vector layer to SpatiaLite format you can do this by right clicking the layer in the legend. Then click on Save as.., define the name of the output file, select ‘SpatiaLite’ as format and the CRS. Also you can select ‘SQLite’ as format, and then add SPATIALITE=YES in the OGR data source creation option field. This tells OGR to create a SpatiaLite database. See also http://www.gdal.org/ogr/drv_sqlite.html. QGIS also supports editable views in SpatiaLite. Creating a new SpatiaLite layer If you want to create a new SpatiaLite layer, please refer to section Creating a new SpatiaLite layer. Tip: SpatiaLite data management Plugins For SpatiaLite data management you can also use several Python plugins: QSpatiaLite, SpatiaLite Manager or DB Manager (core plugin, recommended). They can be downloaded and installed with the Plugin Installer.

12.1.9 MSSQL Spatial Layers Add MSSQL Spatial Layer is part of the new toolbar QGIS also provides native MS SQL 2008 support. The button or available in the MS SQL node in the QBrowser tree, providing drag and drop import support.

12.1.10 ORACLE Spatial Layers Add ORACLE Spatial Layer QGIS also provides native ORACLE Locator/Spatial support. The is part of the new toolbar button or available in the ORACLE node in the QBrowser tree, providing drag and drop import support. ORACLE Spatial layers are stored in an ORACLE database.

Creating a stored Connection The first time you use a ORACLE Spatial data source, you must create a connection to the database that conAdd ORACLE Spatial Layer tains the data. Begin by clicking on the toolbar button, selecting the Add ORACLE Spatial Layer... option from the Layer menu or typing Ctrl+Shift+O. To access the connection manager, click on the [New] button to display the Create a New ORACLE Spatial Connection dialog. The parameters required for a connection are:

• Name: A name for this connection. Can be the same as Database • Database SID or SERVICE_NAME of the Oracle instance. • Host: Name of the database host. This must be a resolvable host name the same as would be used to open a telnet connection or ping the host. If the database is on the same computer as QGIS, simply enter ‘localhost’ here. • Port: Port number the PostgreSQL database server listens on. The default port is 1521. • Username: User name used to login to the database. • Password: Password used with Username to connect to the database. Optional you can activate following checkboxes: •

Save Username Indicates whether to save the database user name in the connection configuration.

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•

Save Password Indicates whether to save the database password in the connection settings. Passwords are saved in clear text in the system configuration and in the project files!

•

Only look in meta data table Restricts the displayed tables to those that are in the all_sdo_geom_metadata view. This can speed up the initial display of spatial tables.

•

Only look for user’s tables When searching for spatial tables restrict the search to tables that are owner by the user.

•

Also list tables with no geometry Indicates that tables without geometry should also be listed by default.

•

Use estimated table statistics for the layer metadata When the layer is setup various metadata is required for the Oracle table. This includes information such as the table row count, geometry type and spatial extents of the data in the geometry column. If the table contains a large number of rows determining this metadata is time consuming. By activating this option the following fast table metadata operations are done: Row count is determined from all_tables.num_rows. Table extents are always determined with the SDO_TUNE.EXTENTS_OF function even if a layer filter is applied. The table geometry is determined from the first 100 non-null geometry rows in the table.

•

Only existing geometry types Only list the existing geometry types and don’t offer to add others.

Once all parameters and options are set, you can test the connection by clicking on the [Test Connect] button. Tip: QGIS User Settings and Security Depending on your computing environment, storing passwords in your QGIS settings may be a security risk. Passwords are saved in clear text in the system configuration and in the project files! Your customized settings for QGIS are stored based on the operating system: •

, the settings are stored in your home directory in .config/QGIS/QGIS2.conf.

•

, the settings are stored in the registry.

Loading a ORACLE Spatial Layer Once you have one or more connections defined, you can load layers from the ORACLE database. Of course this requires having data in ORACLE. To load a layer from ORACLE Spatial, perform the following steps: • If the Add ORACLE Spatial layers dialog is not already open, click on the button.

Add ORACLE Spatial Layer

toolbar

• Choose the connection from the drop-down list and click [Connect]. • Select or unselect

Also list tables with no geometry

Search Options to define which features to load from the layer or use the [Build • Optionally use some query] button to start the Query builder dialog. • Find the layer(s) you wish to add in the list of available layers. • Select it by clicking on it. You can select multiple layers by holding down the Shift key while clicking. See Section Query Builder for information on using the ORACLE Query Builder to further define the layer. • Click on the [Add] button to add the layer to the map. Tip: ORACLE Spatial Layers Normally an ORACLE Spatial layer is defined by an entry in the USER_SDO_METADATA table.

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12.2 The Vector Properties Dialog The Layer Properties dialog for a vector layer provides information about the layer, symbology settings and labeling options. If your vector layer has been loaded from a PostgreSQL/PostGIS datastore, you can also alter the underlying SQL for the layer by invoking the Query Builder dialog on the General tab. To access the Layer Properties dialog, double-click on a layer in the legend or right-click on the layer and select Properties from the popup menu.

Gambar 12.6: Vector Layer Properties Dialog

12.2.1 Style Menu The Style menu provides you with a comprehensive tool for rendering and symbolizing your vector data. You can use Layer rendering → tools that are common to all vector data and special symbolizing tools that were designed for the different kinds of vector data. Layer rendering • Layer transparency : you can make the underlying layer in the map canvas visible with this tool. Use the slider to adapt the visibility of your vector layer to your needs. You can also make a precise definition of the percentage of visibility in the the menu beside the slider. • Layer blending mode: you can achieve special rendering effects with these tools that you previously only know from graphics programs. The pixels of your overlaying and underlaying layers are mixed through the settings described below. – Normal: This is the standard blend mode which uses the alpha channel of the top pixel to blend with the Pixel beneath it; the colors aren’t mixed – Lighten: It selects the maximum of each component from the foreground and background pixels. Be aware that the results tend to be jagged and harsh. – Screen: Light pixels from the source are painted over the destination, while dark pixels are not. This mode is most useful for mixing the texture of one layer with another layer. E.g. you can use a hillshade to texture another layer

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– Dodge: Dodge will brighten and saturate underlying pixels based on the lightness of the top pixel. So brighter top pixels cause the saturation and brightness of the underlying pixels to increase. This works best if the top pixels aren’t too bright, otherwise the effect is too extreme. – Addition: This blend mode simply adds pixel values of one layer with the other. In case of values above 1 (in the case of RGB), white is displayed. This mode is suitable for highlighting features. – Darken: Creates a resultant pixel that retains the smallest components of the foreground and background pixels. Like lighten, the results tend to be jagged and harsh – Multiply: It multiplies the numbers for each pixel of the top layer with the corresponding pixel for the bottom layer. The results are darker pictures. – Burn: Darker colors in the top layer causes the underlying layers to darken. Can be used to tweak and colorise underlying layers. – Overlay: Combines multiply and screen blending modes. In the resulting picture light parts of the picture become lighter and dark parts become darker. – Soft light: Very similar to overlay, but instead of using multiply/screen it uses color burn/dodge. This one is supposed to emulate shining a soft light onto an image. – Hard light: Hard light is very similar to the overlay mode. It’s supposed to emulate projecting a very intense light onto an image. – Difference: Difference subtracts the top pixel from the bottom pixel or the other way round, to always get a positive value. Blending with black produces no change, as values for all colors are 0. – Subtract: This blend mode simply subtracts pixel values of one layer with tshe other. In case of negative values, black is displayed. Since QGIS 2.0 the old symbology is no longer available. In this version the new symbology has been redesigned and revised. Renderers The renderer is responsible for drawing a feature together with the correct symbol. There are four types of renderers: single symbol, categorized, graduated and rule-based. There is no continuous color renderer, because it is in fact only a special case of the graduated renderer. The categorized and graduated renderer can be created by specifying a symbol and a color ramp - they will set the colors for symbols appropriately. For point layers there is a point displacement renderer available. For each data type (points, lines and polygons) vector symbol layer types are available. Depending on the chosen renderer, the Style menu provides different following sections. On the bottom right of the symbology dialog there is a [Symbol] button which gives access to the Style Manager (see Section vector_style_manager). The Style Manager allows you to edit and remove existing symbols and add new ones. Tip: Select and change multiple symbols The Symbology allows to select multiple symbols and right click to change color, transparency, size, or width of selected entries. Single Symbol Renderer The Single Symbol Renderer is used to render all features of the layer using a single user-defined symbol. The properties, that can be adjusted in the Style menu, depend partially on the type of the layer, but all types share the following structure. In the top left part of the menu, there is a preview of the current symbol to be rendered. On the right part of the menu, there is a list of symbols already defined for the current style, prepared to be used via selecting them from the list. The current symbol can be modified using the menu on the right side. If you click on the first level in the Symbol layers dialog on the left side it’s possible to define basic parameters like Size, Transparency, Color and Rotation. Here the layers are joined together. More detailed settings can be made when clicking on the second level in the Symbol layers dialog. You can define Symbol layers that are combined afterwards. A symbol can consist of several Symbol layers. The following settings are possible: 74

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Gambar 12.7: Single symbol line properties • Symbol layer type: You have the possibility to use Ellipse markers, Font markers, Simple markers, SVG markers and Vector Field markers • Size • Angle • Colors • Border width • Offset X,Y: You can shift the symbol in x- or y-direction Note that once you have set the size in the lower levels the size of the whole symbol can be changed with the Size menu in the first level again. The size of the lower levels changes accordingly while the size ratio is maintained. After having done any needed changes, the symbol can be added to the list of current style symbols (using the [Symbol]

Save in symbol library) and then easily be used in the future. Furthermore you can use the [Save

Style] button to save the symbol as a QGIS layer style file (.qml) or SLD file(.sld). Currently in version 2.0 SLDs can be exported from any type of renderer: single symbol, categorized, graduated or rule-based, but when importing an SLD, either a single symbol or rule-based renderer is created. That means that categorized or graduated styles are converted to rule-based. If you want to preserve those renderers, you have to stick to the QML format. On the other hand, it could be very handy sometimes to have this easy way of converting styles to rulebased. With the Style manager from the [Symbol]

menu you can administrate your symbols. You can

add item

edit item remove item share item , , and . ‘Marker’ symbols, ‘Line’ symbols, ‘Fill’ patterns and ‘Color ramps’ can be used to create the symbols (see defining_symbols). The symbols are assigned to ‘All Symbols’, ‘Groups’ or ‘Smart groups’ then.

Categorized Renderer The Categorized Renderer is used to render all features from a layer, using a single user-defined symbol, which color reflects the value of a selected feature’s attribute. The Style menu allows you to select: • The attribute (using the Column listbox) • The symbol (using the Symbol dialog) • The colors (using the Color Ramp listbox)

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The [Advanced] button in the lower right corner of the dialog allows to set the fields containing rotation and size scale information. For convenience, the list in the center of the menu lists the values of all currently selected attributes together, including the symbols that will be rendered. The example in figure_symbology_2 shows the category rendering dialog used for the rivers layer of the QGIS sample dataset.

Gambar 12.8: Categorized Symbolizing options You can create a custom color ramp choosing New color ramp... from the Color ramp dropdown menu. A dialog will prompt for the ramp type: Gradient, Random, ColorBrewer, and cpt-city. The first three have options for number of steps and/or multiple stops in the color ramp. See figure_symbology_3 for an example of custom color ramp and figure_symbology_3a for the cpt-city dialog.

Gambar 12.9: Example of custom gradient color ramp with multiple stops The cpt-city option opens a new dialog with hundreds of themes included ‘out of the box’. Graduated Renderer The Graduated Renderer is used to render all the features from a layer, using a single user-defined symbol, whose color reflects the classification of a selected feature’s attribute to a class. Like Categorized Renderer, it allows to define rotation and size scale from specified columns. 76

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Gambar 12.10: cpt-city dialog with hundreds of color ramps

Gambar 12.11: Graduated Symbolizing options

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Analogue to the categorized rendered, the Style tab allows you to select: • The attribute (using the Column listbox) • The symbol (using the Symbol Properties button) • The colors (using the Color Ramp list) Additionally, you can specify the number of classes and also the mode how to classify features inside the classes (using the Mode list). The available modes are: • Equal Interval • Quantile • Natural Breaks (Jenks) • Standard Deviation • Pretty Breaks The listbox in the center part of the Style menu lists the classes together with their ranges, labels and symbols that will be rendered. The example in figure_symbology_4 shows the graduated rendering dialog for the rivers layer of the QGIS sample dataset. Rule-based rendering The rule-based renderer is used to render all the features from a layer, using rule based symbols, whose color reflects the classification of a selected feature’s attribute to a class. The rules are based on SQL statements. The dialog allows rule grouping by filter or scale and you can decide if you want to enable symbol levels or use only first matched rule. The example in figure_symbology_5 shows the rule-based rendering dialog for the rivers layer of the QGIS sample dataset. To create a rule, activate an existing row by clicking on it or click on ‘+’ and click on the new rule. Then press the button to open [Edit rule] button. In the Rule properties dialog you can define a label for the rule. Press the the Expression builder. In the Function List, click on Fields and Values to view all attributes of the attribute table to be searched. To add an attribute to the Field calculator Expression field, double click its name in the Fields and Values list. Generally you can use the various fields, values and functions to construct the calculation expression or you can just type it into the box (see Field Calculator).

Gambar 12.12: Rule-based Symbolizing options Point displacement

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The point displacement renderer offers to visualize all features of a point layer, even if they have the same location. To do this, the symbols of the points are placed on a displacement circle around a center symbol.

Gambar 12.13: Point displacement dialog

Tip: Export vector symbology You have the possibility to export vector symbology from QGIS into the Google .kml, *.dxf and MapInfo.tab files. Just open the right mouse menu of the layer and click on Save selection as → to define the name of the output file and its format. Use the Symbology export menu to save the symbology either as Feature symbology → or as Symbol layer symbology →. If you have used symbol layers it is recommended to use the second setting.

12.2.2 Labels Menu Labels The core application provides smart labeling for vector point, line and polygon layers and only requires a few parameters. This new application also supports on-the-fly transformated layers. The core functions of the application have been redesigned. In QGIS 2.0. there are now a number of other features which improve the labeling. The following menus have been created for labeling the vector layers:

• Text • Formatting • Buffer • Background • Shadow • Placement • Rendering Let us see how the new menus can be used for various vector layers. Labeling point layers

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Start QGIS and load a vector point layer. Activate the layer in the legend and click on the icon in the QGIS toolbar menu.

Layer Labeling Options

Label this layer with checkbox and select an attribute column to use for labeling. First step is to activate the Click if you want to define labels based on expressions. The following steps describe a simple labeling without using the Data defined override functions that are situated next to the drop-down menus. You can define the text style in the Text menu (see Figure_labels_1 ). A new function is the Type case option where you can influence the text rendering. You have the possibility to render the text ‘All uppercase’, ‘All lowercase’ or ‘Capitalize first letter’. Also, a new function in QGIS 2.0 is the use of blend modes (see blend_modes). In the Formatting menu you can define a character for a line break in the labels with the wrap label on character Formatted numbers option to format the numbers in an attribute table. Here decimal places function. Use the are inserted. If you enable this option three decimal places ist set by default. To create a buffer just activate Draw text buffer checkbox in the Buffer menu. The buffer color is variable. Also, a new function in QGIS 2.0 is the use of blend modes (see blend_modes). Color buffer’s fill checkbox is activated, it will interact with partially transparent text and give mixed If the color transparency results. Turning off the buffer fill fixes that issue (except where the interior aspect of the buffer’s stroke intersects with the text’s fill) and also allows the user to make outlined text. In the Background menu you can define with Size X and Size Y the shape of your background. Use Size type to insert an additional ‘Buffer’ into your background. The buffer size one is set by default here. The background then consists of the buffer plus the background in Size X and Size Y. You can set a Rotation where you can choose between ‘Sync with label’, ‘Offset of label’ and ‘Fixed’. Using ‘Offset of label’ and ‘Fixed’ you can rotate the background. Define an Offset X,Y with X and Y values and the background will be shifted. When applying Radius X,Y the background gets rounded corners. Again, it is possible to mix the background with the underlying layers in the map canvas using the Blend mode (see blend_modes). Use the Shadow menu for a user-defined Drop shadow. The drawing of the background is very variable. Choose between ‘Lowest label component’, ‘Text’, ‘Buffer’ and ‘Background’. The Offset angle depends on the orientation of the label. If you choose the Use global shadow checkbox then the zero point of the angle is always oriented to the north and doesn’t depend on the orientation of the label. Influence the appearance of the shadow with the Blur radius. The higher the number, the softer the shadows. The appearance of the drop shadow can also be altered by choosing a blend mode (see blend_modes). Choose the Placement menu for the label placement and the labeling priority. Using the Offset from point setting you now have the possibility to use Quadrants to place your label. Additionally you can alter the angle of the label placement with the Rotation setting. Thus, a placement in a certain quadrant with a certain rotation is possible. In the Rendering menu you can define label and feature options. In the Label options you find the scale-based visibility setting now. You can prevent QGIS from rendering only selected labels with the Show all labels for this layer (including colliding labels) checkbox. In the Feature options you can define if every part of a multipart feature is to be labeled. In QGIS 2.0 now it’s possible to define if the number of features to be labeled is limited and to

Discourage labels from covering features.

Labeling line layers First step is to activate the to use for labeling. Click

Label this layer checkbox in the Label settings tab and select an attribute column if you want to define labels based on expressions.

After that you can define the text style in the Text menu. Here the same settings as for point layers are possible. Also in the Formatting menu the same settings as for point layers are possible. The Buffer menu has the same functions as described in section labeling_point_layers . The Background menu has the same entries as described in section labeling_point_layers .

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Gambar 12.14: Smart labeling of vector point layers Also the Shadow menu has the same entries as described in section labeling_point_layers . Parallel, Curved In the Placement menu you find special settings for line layers. The label can be placed or Horizontal. With the Parallel and Curved option come the following settings: You can define the Above line, On line and Below line. It’s possible to select several options at once. QGIS will position look for the optimal position of the label then. Remember that here you can also use the line orientation for the position of the label. Additionally you can define a Maximum angle between curved characters when selecting the Curved option (see Figure_labels_2 ). The Rendering menu has nearly the same entries as for point layers. In the Feature options you can now Suppress labeling of features smaller than.

Gambar 12.15: Smart labeling of vector line layers Labeling polygon layers First step is to activate the Label this layer checkbox and select an attribute column to use for labeling. Click if you want to define labels based on expressions. In Text menu define the text style. The entries are the same as for point and line layers. 12.2. The Vector Properties Dialog

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The Formatting menu allows you to format multiple lines like for point and line layers. As with point and line layers you can create a text buffer in the Buffer menu. Use the Background menu to create a complex user-defined background for the polygon layer. You can use the menu as well as for the point and line layers. The entries in the Shadow menu are the same as for point and line layers. In the Placement menu you find special settings for polygon layers (see Figure_labels_3 ). Horizontal (slow), Around centroid, Free and Using perimeter are possible.

Offset from centroid,

In the Offset from centroid settings you can define if the centroid is visible polygon or whole polygon. That means that either the centroid is used for the polygon you can see on the map or the centroid is used for the whole polygon, no matter if you can see the whole feature on the map. You can place your label with the quadrants Around centroid setting makes it possible to place the label around the here and define offset and rotation. The centroid with a certain distance. Again, you can define visible polygon or whole polygon for the centroid. With the Above line,

Using perimeter settings you can define a position and a distance for the label. For the position On line,

Below line and

Line orientation dependend position are possible.

The entries in the Rendering menu are the same as for line layers. You can also use Suppress labeling of features smaller than in the Feature options.

Gambar 12.16: Smart labeling of vector polygon layers Using data-defined override for labeling With the data-defined override functions the settings for the labeling are overwritten by entries in the attribute table. You can activate/deactivate the function with the right-mouse button. Hover over the symbol and you see the information about the data-defined override, including the current definition field. We now describe an example how to use the data-defined override function for the

Move label

function (see figure_labels_4 ).

1. Import the lakes.shp from the QGIS sample dataset. 2. Double-klick the layer to open the Layer Properties. Klick on Labels and Placement. Select centroid.

Offset from

-Icon to define the field type for the Coordinate. Choose 3. Look for the Data defined entries. Klick the ‘xlabel’ for X and ‘ylabel’ for Y. The Icons are now highlighted in yellow. 4. Zoom into a lake.

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5. Go to the Label toolbar and klick the Icon. Now you can shift the label manually to another position (see figure_labels_5 ). The new position of the label is saved in the ‘xlabel’ and ‘ylabel’ columns of the attribute table.

Gambar 12.17: Labeling of vector polygon layers with data-defined override

Gambar 12.18: Move labels

12.2.3 Fields Menu Within the Fields menu the field attributes of the selected dataset can be manipulated. The buttons New Column

and

Delete Column

can be used, when the dataset is

Editing mode

.

Edit Widget Within the Fields menu you also find an edit widget column. This column can be used to define values or a range of values that are allowed to be added to the specific attribute table column. If you click on the [edit widget] button, a dialog opens, where you can define different widgets. These widgets are: • Line edit: an edit field which allows to enter simple text (or restrict to numbers for numeric attributes). • Classification: Displays a combo box with the values used for classification, if you have chosen ‘unique value’ as legend type in the Style menu of the properties dialog. 12.2. The Vector Properties Dialog

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Gambar 12.19: Dialog to select an edit widget for an attribute column • Range: Allows to set numeric values from a specific range. The edit widget can be either a slider or a spin box. • Unique values: The user can select one of the values already used in the attribute table. If editable is activated, a line edit is shown with autocompletion support, otherwise a combo box is used. • File name: Simplifies the selection by adding a file chooser dialog. • Value map: a combo box with predefined items. The value is stored in the attribute, the description is shown in the combo box. You can define values manually or load them from a layer or a CSV file. • Enumeration: Opens a combo box with values that can be used within the columns type. This is currently only supported by the postgres provider. • Immutable: The immutable attribute column is read-only. The user is not able to modify the content. • Hidden: A hidden attribute column is invisible. The user is not able to see its content. • Checkbox: Displays a checkbox and you can define what attribute is added to the column when the checkbox is activated or not. • Text edit: This opens a text edit field that allows multiple lines to be used. • Calendar: Opens a calendar widget to enter a date. Column type must be text. • Value Relation: Offers values from a related table in a combobox. You can select layer, key column and value column. • UUID Generator: Generates a read-only UUID (Universally Unique Identifiers) field, if empty. • Photo: Field contains a filename for a picture. The width and height of the field can be defined. • Webview: Field contains an URL. The width and height of the field is variable. • Color: A field which allows to enter color codes. During data entry the color is visible through a color bar included in the field. With the Attribute editor layout you can now define builtin forms for data entry jobs (see figure_fields_2). Choose ‘Drag and drop designer’ and an attribute column. Use the Icon to create a category that then will be shown during the digitizing session (see figure_fields_3). Next step will be to assign the relevant fields to the

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category with the Icon. You can create more categories and use the same fields again. When creating a new category QGIS will insert a new tab for the category in the built in form. Other options in the dialog are ‘Autogenerate’ and ‘Provide ui-file’. ‘Autogenerate’ just creates Editors for all fields and tabulates them. The ‘Provide ui-file’ option allows you to use complex dialogs made with the Qt-Designer. Using an UI-file allows a large freedom in creating a dialog. For detailed information see http://nathanw.net/2011/09/05/qgis-tips-custom-feature-forms-with-python-logic/ . QGIS dialogs can have a python function that is called when the dialog is opened. Use this function to add extra logic to your dialogs. An example is (in module MyForms.py): def open(dialog,layer,feature): geom = feature.geometry() control = dialog.findChild(QWidged,"My line edit")

Reference in Python Init Function like so: MyForms.open MyForms.py must live on PYTHONPATH, .qgis2/python, or inside the project folder

Gambar 12.20: Dialog to create categories with the Attribute editor layout

12.2.4 General Menu Use this menu to make general settings for the vector layer. There are several options available: Layer Info • Change the display name of the layer in displayed as • Define the Layer source of the vector layer • Define the Data source encoding to define provider specific option and to be able to read the file Coordinate Reference System • Specify the Coordinate Reference System. Here you can view or change the projection of the specific vector layer. • Create a Spatial Index (only for OGR supported formats) 12.2. The Vector Properties Dialog

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Gambar 12.21: Resulting built in form in a data entry session • Update Extents information for a layer • View or change the projection of the specific vector layer, clicking on Specify ... Scale dependent visibility • You can set the Maximum (inclusive) and Minimum (exclusive) scale. The scale can also be set by the [Current] buttons Feature subset • With the [Query Builder] button you can create a subset of the features in the layer that will be visualized (also refer to section Save selected features as new layer).

Gambar 12.22: General menu in vector layers properties dialog

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12.2.5 Display Menu In QGIS 2.0 there is now an own menu for the map tips. It includes a new feature: Map Tip display text in HTML. While you can still choose a Field to be displayed when hovering over a feature on the map it is now possible to insert HTML code that creates a complex display when hovering over a feature. To activate Map Tips, select the menu option View → MapTips.Figure Display 1 shows an example of HTML code.

Gambar 12.23: HTML code for map tip

Gambar 12.24: Map tip made with HTML code

12.2.6 Actions Menu QGIS provides the ability to perform an action based on the attributes of a feature. This can be used to perform any number of actions, for example, running a program with arguments built from the attributes of a feature or passing parameters to a web reporting tool. Actions are useful when you frequently want to run an external application or view a web page based on one or more values in your vector layer. They are devided into 6 types and can be used like this: • Generic, Mac, Windows and Unix actions start an external process, • Python actions execute a python expression, • Generic and Python actions are visible everywhere, 12.2. The Vector Properties Dialog

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Gambar 12.25: Overview action dialog with some sample actions • Mac, Windows and Unix actions are visible only on the respective platform (i.e. you can define three ‘Edit’ actions to open an editor and the users can only see and execute the one ‘Edit’ action for their platform to run the editor). There are several examples included in the dialog. You can load them clicking on [Add default actions]. An example is performing a search based on an attribute value. This concept is used in the following discussion. Defining Actions Attribute actions are defined from the vector Layer Properties dialog. To define an action, open the vector Layer Properties dialog and click on the Actions menu. Go to the Action properties. Select ‘Generic’ as type and provide a descriptive name for the action. The action itself must contain the name of the application that will be executed when the action is invoked. You can add one or more attribute field values as arguments to the application. When the action is invoked any set of characters that start with a % followed by the name of a field will be replaced by the value of that field. The special characters %% will be replaced by the value of the field that was selected from the identify results or attribute table (see using_actions below). Double quote marks can be used to group text into a single argument to the program, script or command. Double quotes will be ignored if preceded by a backslash. If you have field names that are substrings of other field names (e.g., col1 and col10) you should indicate so, by surrounding the field name (and the % character) with square brackets (e.g., [%col10]). This will prevent the %col10 field name being mistaken for the %col1 field name with a 0 on the end. The brackets will be removed by QGIS when it substitutes in the value of the field. If you want the substituted field to be surrounded by square brackets, use a second set like this: [[%col10]]. Using the Identify Features tool you can open Identify Results dialog. It includes a (Derived) item that contains information relevant to the layer type. The values in this item can be accessed in a similar way to the other fields by using preceeding the derived field name by (Derived).. For example, a point layer has an X and Y field and the value of these can be used in the action with %(Derived).X and %(Derived).Y. The derived attributes are only available from the Identify Results dialog box, not the Attribute Table dialog box. Two example actions are shown below: • konqueror http://www.google.com/search?q=%nam • konqueror http://www.google.com/search?q=%% In the first example, the web browser konqueror is invoked and passed a URL to open. The URL performs a Google search on the value of the nam field from our vector layer. Note that the application or script called by

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the action must be in the path or you must provide the full path. To be sure, we could rewrite the first example as: /opt/kde3/bin/konqueror http://www.google.com/search?q=%nam. This will ensure that the konqueror application will be executed when the action is invoked. The second example uses the %% notation which does not rely on a particular field for its value. When the action is invoked, the %% will be replaced by the value of the selected field in the identify results or attribute table. Using Actions Actions can be invoked from either the Identify Results dialog, an Attribute Table dialog or from Run FeaIdentify Features Open Attribute Table or or ture Action (recall that these dialogs can be opened by clicking ). To invoke an action, right click on the record and choose the action from the popup menu. Actions are listed in the popup menu by the name you assigned when defining the actions. Click on the action you wish to invoke. Run Feature Action

If you are invoking an action that uses the %% notation, right-click on the field value in the Identify Results dialog or the Attribute Table dialog that you wish to pass to the application or script. Here is another example that pulls data out of a vector layer and inserts them into a file using bash and the echo command (so it will only work or perhaps ). The layer in question has fields for a species name taxon_name, latitude lat and longitude long. I would like to be able to make a spatial selection of a localities and export these field values to a text file for the selected record (shown in yellow in the QGIS map area). Here is the action to achieve this: bash -c "echo \"%taxon_name %lat %long\" >> /tmp/species_localities.txt"

After selecting a few localities and running the action on each one, opening the output file will show something like this: Acacia Acacia Acacia Acacia

mearnsii mearnsii mearnsii mearnsii

-34.0800000000 -34.9000000000 -35.2200000000 -32.2700000000

150.0800000000 150.1200000000 149.9300000000 150.4100000000

As an exercise we create an action that does a Google search on the lakes layer. First we need to determine the URL needed to perform a search on a keyword. This is easily done by just going to Google and doing a simple search, then grabbing the URL from the address bar in your browser. From this little effort we see that the format is: http://google.com/search?q=qgis, where QGIS is the search term. Armed with this information, we can proceed: 1. Make sure the lakes layer is loaded. 2. Open the Layer Properties dialog by double-clicking on the layer in the legend or right-click and choose Properties from the popup menu. 3. Click on the Actions menu. 4. Enter a name for the action, for example Google Search. 5. For the action, we need to provide the name of the external program to run. In this case, we can use Firefox. If the program is not in your path, you need to provide the full path. 6. Following the name of the external application, add the URL used for doing a Google search, up to but not included the search term: http://google.com/search?q= 7. The text in the Action field should now look like this: firefox http://google.com/search?q= 8. Click on the drop-down box containing the field names for the lakes layer. It’s located just to the left of the [Insert Field] button. 9. From the drop-down box select ‘NAMES’ and click [Insert Field]. 10. Your action text now looks like this: firefox http://google.com/search?q=%NAMES 11. To finalize the action click the [Add to action list] button.

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This completes the action and it is ready to use. The final text of the action should look like this: firefox http://google.com/search?q=%NAMES

We can now use the action. Close the Layer Properties dialog and zoom in to an area of interest. Make sure the lakes layer is active and identify a lake. In the result box you’ll now see that our action is visible:

Gambar 12.26: Select feature and choose action When we click on the action, it brings up Firefox and navigates to the URL http://www.google.com/search?q=Tustumena. It is also possible to add further attribute fields to the action. Therefore you can add a + to the end of the action text, select another field and click on [Insert Field]. In this example there is just no other field available that would make sense to search for. You can define multiple actions for a layer and each will show up in the Identify Results dialog. You can think of all kinds of uses for actions. For example, if you have a point layer containing locations of images or photos along with a file name, you could create an action to launch a viewer to display the image. You could also use actions to launch web-based reports for an attribute field or combination of fields, specifying them in the same way we did in our Google search example. We can also make more complex examples, for instance on how to use Python actions. Usually when we create an action to open a file with an external application we can use absolute paths, or eventually relative paths, in the second case the path is relative to the location of the external program executable file. But what about we need to use relative paths, relative to the selected layer (a file based one, like a shapefile or spatialite)? The following code will do the trick: command = "firefox"; imagerelpath = "images_test/test_image.jpg"; layer = qgis.utils.iface.activeLayer(); import os.path; layerpath = layer.source() if layer.providerType() == ’ogr’ \ else (qgis.core.QgsDataSourceURI(layer.source()).database() \ if layer.providerType() == ’spatialite’ else None); path = os.path.dirname(str(layerpath)); image = os.path.join(path,imagerelpath); import subprocess; subprocess.Popen( [command, image ] );

we have to just remember that the action is one of type Python and to change the command and imagerelpath variables to fit our needs.

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But what about if the relative path need to be relative to the (saved) project file? The code of the Python action would be: command="firefox"; imagerelpath="images/test_image.jpg"; projectpath=qgis.core.QgsProject.instance().fileName(); import os.path; path=os.path.dirname(str(projectpath)) if projectpath != ’’ else None; image=os.path.join(path, imagerelpath); import subprocess; subprocess.Popen( [command, image ] );

Another Python actions example if the one that allows us to add new layers to the project. For instance the following examples will add to the project respectively a vector and a raster. The name of files to be added to the project and the name to be given to the layer are data driven (filename and layname are column names of the table of attributes of the vector where the action was created): qgis.utils.iface.addVectorLayer(’/yourpath/[% "filename" %].shp’,’[% "layername" %]’,\ ’ogr’)

To add a raster (a tif image in this example) it becomes: qgis.utils.iface.addRasterLayer(’/yourpath/[% "filename" %].tif’,’[% "layername" %]’)

12.2.7 Joins Menu The Joins menu allows you to join a loaded attribute table to a loaded vector layer. After clicking the Add vector join dialog appears. As key columns you have to define a join layer you want to connect with the target vector layer , a join field that corresponds to an attribute column in the target layer and a target field you find in the attribute table of the target vector layer here. As a result, all information of the join layer and the target layer are displayed in the attribute table of the target layer as joined information. QGIS currently supports to join non spatial table formats supported by OGR (e.g. CSV, DBF and Excel), delimited text and the PostgreSQL provider (see figure_joins_1).

Gambar 12.27: Join an attribute table to an existing vector layer Additionally the add vector join dialog allows to: •

Cache join layer in virtual memory

•

Create attribute index on the join field

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12.2.8 Diagrams Menu The Diagrams menu allows you to add a graphic overlay to a vector layer (see figure_diagrams_1). The current core implementation of diagrams provides support for piecharts, text diagrams and histograms. The menu is divided into four tabs now: Appearance, Size, Postion and Options. In the case of the text diagram and piechart text values of different data columns are displayed one below the other with a circle or a box and dividers. In the Size tab diagram size is based on a fixed size or on linear scaling according to a classification attribute. The placement of the diagrams which is done in the Position tab interacts with the new labeling, so position conflicts between diagrams and labels are detected and solved. In addition to chart positions can be fixed by the users hand.

Gambar 12.28: Vector properties dialog with diagram menu We will demonstrate an example and overlay the alaska boundary layer a text diagram showing some temperature data from a climate vector layer. Both vector layers are part of the QGIS sample dataset (see Section Contoh data). Load Vector 1. First click on the icon, browse to the QGIS sample dataset folder and load the two vector shape layers alaska.shp and climate.shp.

2. Double click the climate layer in the map legend to open the Layer Properties dialog. 3. Click on the Diagrams menu, activate ‘Text diagram’

Display diagrams and from Diagram type

combobox select

4. In the Appearance tab we choose a light blue as Background color and in the Size tab we set a fixed size to 18 mm. 5. In the Position tab Placement could be set to AroundPoint. 6. In the diagram we want to display the values of the three columns T_F_JAN, T_F_JUL and T_F_MEAN. First select T_F_JAN as Attributes and click the

button, then T_F_JUL and finally T_F_MEAN.

7. Now click [Apply] to display the diagram in the QGIS main window. 8. You can now adapt the chart size in the Size tab. Deactivate the Fixed size and set the size of the diagrams on the basis of an Attribute with the [Find maximum value] button and the Size menu. If diagrams appear too small on the screen you can activate the Minimum size of the diagrams. 92

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9. Change the Attribute Colors by double clicking on the color values in the Assigned attributes field. Figure_diagrams_2 gives an impression. 10. Finally click [Ok].

Gambar 12.29: Diagram from temperature data overlayed on a map Remember that in the Position tab a Data defined position of the diagrams is possible. Here you can use attributes to define the position of the diagram. Also, a scale dependent visibility that you can find in the Appearance tab is possible.

12.2.9 Metadata Menu The Metadata menu consists of a Description, Attribution, MetadataURL and Properties section. In the Properties section you get general information about the layer, including specifics about the type and location, number of features, feature type, and the editing capabilities in the Properties section. The Extents table provides you with layer extent information, and the Layer Spatial Reference System information, providing information about the CRS of the layer. This is a quick way to get information about the layer. Additionally you can add/edit a title for the layer and some abstract information in the Description. Also, it’s possible to define a Keyword list here. These keyword lists can be used in a metadata catalogue. If you want to use a title from an XML metadata file you have to fill in a link in the DataUrl field. Use Attribution to get Atrribute data from an XML metadata catalogue. In MetadataUrl you can define the general path to the XML metadata catalogue. These information will be saved in the QGIS project file for following sessions and will be used for QGIS server.

12.3 Editing QGIS supports various capabilities for editing OGR, SpatiaLite, PostGIS, MSSQL Spatial and Oracle Spatial vector layers and tables. Catatan: The procedure for editing GRASS layers is different - see Section Digitizing and editing a GRASS vector layer for details. Tip: Concurrent Edits

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Gambar 12.30: Metadata menu in vector layers properties dialog This version of QGIS does not track if somebody else is editing a feature at the same time as you. The last person to save their edits wins.

12.3.1 Setting the Snapping Tolerance and Search Radius Before we can edit vertices, we must set the snapping tolerance and search radius to a value that allows us an optimal editing of the vector layer geometries. Snapping tolerance Snapping tolerance is the distance QGIS uses to search for the closest vertex and/or segment you are trying to connect when you set a new vertex or move an existing vertex. If you aren’t within the snapping tolerance, QGIS will leave the vertex where you release the mouse button, instead of snapping it to an existing vertex and/or segment. The snapping tolerance setting affects all tools which work with tolerance. 1. A general, project wide snapping tolerance can be defined choosing Settings → Options. On Mac: go to QIS → Preferences..., on Linux: Edit → Options. In the Digitizing tab you can select between to vertex, to segment or to vertex and segment as default snap mode. You can also define a default snapping tolerance and a search radius for vertex edits. The tolerance can be set either in map units or in pixels. The advantage of choosing pixels, is that the snapping tolerance doesn’t have to be changed after zoom operations. In our small digitizing project (working with the Alaska dataset), we define the snapping units in feet. Your results may vary, but something on the order of 300ft should be fine at a scale of 1:10 000 should be a reasonable setting. 2. A layer based snapping tolerance can be defined by choosing Settings → (or File →) Snapping options... to enable and adjust snapping mode and tolerance on a layer basis (see figure_edit_1 ). Note that this layer based snapping overrides the global snapping option set in the Digitizing tab. So if you need to edit one layer, and snap its vertices to another layer, then enable snapping only on the snap to layer, then decrease the global snapping tolerance to a smaller value. Furthermore, snapping will never occur to a layer which is not checked in the snapping options dialog, regardless of the global snapping tolerance. So be sure to mark the checkbox for those layers that you need to snap to.

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Gambar 12.31: Edit snapping options on a layer basis Search radius Search radius is the distance QGIS uses to search for the closest vertex you are trying to move when you click on the map. If you aren’t within the search radius, QGIS won’t find and select any vertex for editing and it will pop up an annoying warning to that effect. Snap tolerance and search radius are set in map units or pixels, so you may find you need to experiment to get them set right. If you specify too big of a tolerance, QGIS may snap to the wrong vertex, especially if you are dealing with a large number of vertices in close proximity. Set search radius too small and it won’t find anything to move. The search radius for vertex edits in layer units can be defined in the Digitizing tab under Settings → The same place where you define the general, project wide snapping tolerance.

Options.

12.3.2 Zooming and Panning Before editing a layer, you should zoom in to your area of interest. This avoids waiting while all the vertex markers are rendered across the entire layer. pan zoom-in zoom-out Apart from using the and / icons on the toolbar with the mouse, navigating can also be done with the mouse wheel, spacebar and the arrow keys.

Zooming and panning with the mouse wheel While digitizing you can press the mouse wheel to pan inside of the main window and you can roll the mouse wheel to zoom in and out on the map. For zooming place the mouse cursor inside the map area and roll it forward (away from you) to zoom in and backwards (towards you) to zoom out. The mouse cursor position will be the center of the zoomed area of interest. You can customize the behavior of the mouse wheel zoom using the Map tools tab under the Settings → Options menu. Panning with the arrow keys Panning the map during digitizing is possible with the arrow keys. Place the mouse cursor inside the map area and click on the right arrow key to pan east, left arrow key to pan west, up arrow key to pan north and down arrow key to pan south. You can also use the spacebar to temporarily cause mouse movements to pan then map. The PgUp and PgDown keys on your keyboard will cause the map display to zoom in or out without interrupting your digitizing session.

12.3.3 Topological editing Besides layer based snapping options you can also define some topological functionalities in the Snapping options... dialog in the Settings (or File) menu. Here you can define

12.3. Editing

Enable topological editing and/or for

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polygon layers you can activate the column

Avoid Int. which avoids intersection of new polygons.

Enable topological editing Enable topological editing is for editing and maintaining common boundaries in polygon mosaics. The option QGIS ‘detects’ a shared boundary in a polygon mosaic and you only have to move the vertex once and QGIS will take care about updating the other boundary. Avoid intersections of new polygons Avoid Int. column, called Avoid intersections of new polygons avoids The second topological option in the overlaps in polygon mosaics. It is for quicker digitizing of adjacent polygons. If you already have one polygon, it is possible with this option to digitize the second one such that both intersect and QGIS then cuts the second polygon to the common boundary. The advantage is that users don’t have to digitize all vertices of the common boundary. Enable snapping on intersections Enable snapping on intersection. It allows to snap on an intersection of background Another option is to use layers, even if there’s no vertex on the intersection.

12.3.4 Digitizing an existing layer By default, QGIS loads layers read-only: This is a safeguard to avoid accidentally editing a layer if there is a slip of the mouse. However, you can choose to edit any layer as long as the data provider supports it, and the underlying data source is writable (i.e. its files are not read-only). In general, editing vector layers is divided into a digitizing and an advanced digitizing toolbar, described in Section Advanced digitizing. You can select and unselect both under Settings → Toolbars →. Using the basic digitizing tools you can perform the following functions: Icon Purpose Icon Purpose Current edits

Toggle editing

Adding Features: Capture Point

Adding Features: Capture Line

Adding Features: Capture Polygon

Move Feature

Node Tool

Delete Selected

Cut Features

Copy Features

Paste Features

Save layer edits

Table Editing: Vector layer basic editing toolbar All editing sessions start by choosing the clicking on the legend entry for that layer.

Toggle editing

option. This can be found in the context menu after right

Toggle editing Alternately, you can use the Toggle Editing button from the digitizing toolbar to start or stop the editing mode. Once the layer is in edit mode, markers will appear at the vertices, and additional tool buttons on the editing toolbar will become available.

Tip: Save Regularly Remember to

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regularly. This will also check that your data source can accept all the changes.

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Adding Features You can use the digitizing mode.

Add Feature

,

Add Feature

or

Add Feature

icons on the toolbar to put the QGIS cursor into

For each feature, you first digitize the geometry, then enter its attributes. To digitize the geometry, left-click on the map area to create the first point of your new feature. For lines and polygons, keep on left-clicking for each additional point you wish to capture. When you have finished adding points, right-click anywhere on the map area to confirm you have finished entering the geometry of that feature. The attribute window will appear, allowing you to enter the information for the new feature. Figure_edit_2 shows setting attributes for a fictitious new river in Alaska. In the Digitizing menu under the Settings → Options menu, you can also activate attribute values.

Suppress attributes pop-up windows after each created feature

Reuse last entered

Gambar 12.32: Enter Attribute Values Dialog after digitizing a new vector feature

With the

Move Feature(s)

icon on the toolbar you can move existing features.

Tip: Attribute Value Types For editing the attribute types are validated during the entry. Because of this, it is not possible to enter a number into the text-column in the dialog Enter Attribute Values or vice versa. If you need to do so, you should edit the attributes in a second step within the Attribute table dialog.

Current Edits This new feature allows the digitization of multiple layers. Choose

Save for Selected Layers to save all

changes you made in multiple layers. You also have the opportunity to

Rollback for Selected Layers so that

the digitization is then withdrawn for all selected layers. If you want to stop editing the selected layers the Cancel for Selected Layer(s) is an easy way. The same functions for editing all layers of the project are available. Node Tool For shapefile-based layers as well as SpatialLite,PostgreSQL/PostGIS, MSSQL Spatial and Oracle Spatial tables Node Tool the provides manipulation capabilites of feature vertices similar to CAD programs. It is possible to simply select multiple vertices at once and to move, add or delete them alltogether. The node tool also works with ‘on the fly’ projection turned on and supports the topological editing feature. This tool is, unlike other tools in

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QGIS, persistent, so when some operation is done, selection stays active for this feature and tool. If the node tool couldn’t find any features, a warning will be displayed. Important is to set the property Settings → Options → Digitizing → Search Radius: than zero (i.e. 10). Otherwise QGIS will not be able to tell which vertex is being edited.

to a number greater

Tip: Vertex Markers The current version of QGIS supports three kinds of vertex-markers: Semi transparent circle, Cross and None. To change the marker style, choose Options from the Settings menu and click on the Digitizing tab and select the appropriate entry.

Basic operations Start by activating the of this feature.

Node Tool

and selecting a feature by clicking on it. Red boxes will appear at each vertex

• Selecting vertices: You can select vertices by clicking on them one at a time, by clicking on an edge to select the vertices at both ends, or by clicking and dragging a rectangle around some vertices. When a vertex is selected its color changes to blue. To add more vertices to the current selection, hold down the Ctrl key while clicking. Hold down Ctrl or Shift when clicking to toggle the selection state of vertices (vertices that are currently unselected will be selected as usual, but also vertices that are already selected will become unselected). • Adding vertices: To add a vertex simply double click near an edge and a new vertex will appear on the edge near to the cursor. Note that the vertex will appear on the edge, not at the cursor position, therefore it has to be moved if necessary. • Deleting vertices: After selecting vertices for deletion, click the Delete key. Note that you cannot use the Node Tool

to delete a complete feature; QGIS will ensure it retains the minimum number of vertices for

the feature type you are working on. To delete a complete feature use the

Delete Selected

tool.

• Moving vertices: Select all the vertices you want to move. Click on a selected vertex or edge and drag in the direction you wish to move. All the selected vertices will move together. If snapping is enabled, the whole selection can jump to the nearest vertex or line. Each change made with the node tool is stored as a separate entry in the undo dialog. Remember that all operations support topological editing when this is turned on. On the fly projection is also supported, and the node tool provides tooltips to identify a vertex by hovering the pointer over it. Cutting, Copying and Pasting Features Selected features can be cut, copied and pasted between layers in the same QGIS project, as long as destination layers are set to

Toggle editing

beforehand.

Features can also be pasted to external applications as text: That is, the features are represented in CSV format with the geometry data appearing in the OGC Well-Known Text (WKT) format. However in this version of QGIS, text features from outside QGIS cannot be pasted to a layer within QGIS. When would the copy and paste function come in handy? Well, it turns out that you can edit more than one layer at a time and copy/paste features between layers. Why would we want to do this? Say we need to do some work on a new layer but only need one or two lakes, not the 5,000 on our big_lakes layer. We can create a new layer and use copy/paste to plop the needed lakes into it. As an example we are copying some lakes to a new layer: 1. Load the layer you want to copy from (source layer) 2. Load or create the layer you want to copy to (target layer)

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3. Start editing for target layer 4. Make the source layer active by clicking on it in the legend Select Single Feature

5. Use the

Copy Features

6. Click on the

tool to select the feature(s) on the source layer tool

7. Make the destination layer active by clicking on it in the legend Paste Features

8. Click on the

tool

9. Stop editing and save the changes What happens if the source and target layers have different schemas (field names and types are not the same)? QGIS populates what matches and ignores the rest. If you don’t care about the attributes being copied to the target layer, it doesn’t matter how you design the fields and data types. If you want to make sure everything - feature and its attributes - gets copied, make sure the schemas match. Tip: Congruency of Pasted Features If your source and destination layers use the same projection, then the pasted features will have geometry identical to the source layer. However if the destination layer is a different projection then QGIS cannot guarantee the geometry is identical. This is simply because there are small rounding-off errors involved when converting between projections.

Deleting Selected Features If we want to delete an entire polygon, we can do that by first selecting the polygon using the regular Select Single Feature tool. You can select multiple features for deletion. Once you have the selection set, use the Delete Selected

The

tool to delete the features.

Cut Features

tool on the digitizing toolbar can also be used to delete features. This effectively deletes the

feature but also places it on a “spatial clipboard”. So we cut the feature to delete. We could then use the Paste Features tool to put it back, giving us a one-level undo capability. Cut, copy, and paste work on the currently selected features, meaning we can operate on more than one at a time. Saving Edited Layers When a layer is in editing mode, any changes remain in the memory of QGIS. Therefore they are not committed/saved immediately to the data source or disk. If you want to save edits to the current layer but want to continue editing without leaving the editing mode, you can click the off with the discard them.

Toggle editing

Save Layer Edits

button. When you turn editing mode

(or quit QGIS for that matter), you are also asked if you want to save your changes or

If the changes cannot be saved (e.g. disk full, or the attributes have values that are out of range), the QGIS in-memory state is preserved. This allows you to adjust your edits and try again. Tip: Data Integrity It is always a good idea to back up your data source before you start editing. While the authors of QGIS have made every effort to preserve the integrity of your data, we offer no warranty in this regard.

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12.3.5 Advanced digitizing Icon

Purpose

Icon

Purpose

Undo

Redo

Rotate Feature(s)

Simplify Feature

Add Ring

Add Part

Delete Ring

Delete Part

Reshape Features

Offset Curve

Split Features

Merge Selected Features

Rotate Point Symbols

Merge Attributes of Selected Features

Table Advanced Editing: Vector layer advanced editing toolbar Undo and Redo Undo Redo The and tools allow the user to undo or redo vector editing operations. There is also a dockable widget, which shows all operations in the undo/redo history (see Figure_edit_3). This widget is not displayed by default; it can be displayed by right clicking on the toolbar and activating the Undo/Redo check box. Undo/Redo is however active, even if the widget is not displayed.

Gambar 12.33: Redo and Undo digitizing steps When Undo is hit, the state of all features and attributes are reverted to the state before the reverted operation happened. Changes other than normal vector editing operations (for example changes done by a plugin), may or may not be reverted, depending on how the changes were performed. To use the undo/redo history widget simply click to select an operation in the history list; all features will be reverted to the state they were in after the selected operation. Rotate Feature(s) Use the

Rotate Feature(s)

to rotate one or multiple selected features in the map canvas. You first need to select the

Rotate Feature(s) Icon. Then the centroid of the feature appears and will be the rotation features and then press the anchor point. If you selected multiple features the rotation anchor point will be the common center of the features. Press and drag the left mouse button in the desired direction to rotate the selected features.

It’s also possible to create a user-defined rotation anchor point by which the selected feature will rotate. Select the features to rotate and activate the 100

Rotate Feature(s)

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pointer (without pressing the mouse button) to the place where you want the rotation anchor to be moved. Release the Ctrl button when the desired rotation anchor point is reached. Now press and drag the left mouse button in the desired direction to rotate the selected feature(s). Simplify Feature

Simplify Feature tool allows to reduce the number of vertices of a feature, as long as the geometry doesn’t The change. You need to select a feature, it will be highlighted by a red rubber band and a slider appears. Moving the slider, the red rubber band is changing its shape to show how the feature is being simplified. Clicking [OK] the new, simplified geometry will be stored. If a feature cannot be simplified (e.g. MultiPolygons), a message shows up.

Add Ring

Add Ring icon in the toolbar. This means inside an existing area it is You can create ring polygons using the possible to digitize further polygons, that will occur as a ‘hole’, so only the area in between the boundaries of the outer and inner polygons remain as a ring polygon.

Add Part add part You can polygons to a selected multipolygon. The new part polygon has to be digitized outside the selected multipolygon.

Delete Ring

Delete Ring The tool allows to delete ring polygons inside an existing area. This tool only works with polygon layers. It doesn’t change anything when it is used on the outer ring of the polygon. This tool can be used on polygon and multi-polygon features. Before you select the vertices of a ring, adjust the vertex edit tolerance.

Delete Part

Delete Part tool allows to delete parts from multifeatures (e.g. to delete polygons from a multipolygon The feature). It won’t delete the last part of the feature, this last part will stay untouched. This tool works with all multi-part geometries point, line and polygon. Before you select the vertices of a part, adjust the vertex edit tolerance.

Reshape Features Reshape Features You can reshape line and polygon features using the icon on the toolbar. It replaces the line or polygon part from the first to the last intersection with the original line. With polygons this can sometimes lead to unintended results. It is mainly useful to replace smaller parts of a polygon, not major overhauls and the reshape line is not allowed to cross several polygon rings as this would generate an invalid polygon.

For example, you can edit the boundary of a polygon with this tool. First, click in the inner area of the polygon next to the point where you want to add a new vertex. Then, cross the boundary and add the vertices outside the polygon. To finish, right-click in the inner area of the polygon. The tool will automatically add a node where the new line crosses the border. It is also possible to remove part of the area from the polygon, starting the new line outside the polygon, adding vertices inside, and ending the line outside the polygon with a right click.

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Catatan: The reshape tool may alter the starting position of a polygon ring or a closed line. So the point that is represented ‘twice’ will not be the same any more. This may not be a problem for most applications, but it is something to consider.

Offset Curves Offset Curve The tool creates parallel shifts of line layers. The tool can be applied to the edited layer (the geometries are modified) or also to background layers (creates copies of the lines / rings and adds it to the the edited layer). It is thus ideally suited for the creation of distance line layers. The displacement is shown at the bottom left of the taskbar. To create a shift of a line layer you have to go into editing mode and then select the Offset Curve

feature. You can make the can be saved with the

Save Layer Edits

tool active and drag the cross to the desired distance. Your changes then

tool.

Split Features You can split features using the split.

Split Features

icon on the toolbar. Just draw a line across the feature you want to

Merge selected features The

Merge Selected Features

tool allows to merge features that have common boundaries and the same attributes.

Merge attributes of selected features Merge Attributes of Selected Features The tool allows to merge attributes of features with common boundaries and attributes without merging their boundaries. You can merge the attributes when selecting several features at once. Merge Attributes of Selected Features Then press the button. Now QGIS offers you which attributes are to be applied to all selected objects. As a result, all objects have the same attribute entries.

Rotate Point Symbols Rotate Point Symbols allows to change the rotation of point symbols in the map canvas. You have to define a The rotation column from the attribute table of the point layer in the Advanced menu of the Style menu of the Layer

Properties. Also you have to go into the ‘SVG marker’ and choose Data defined properties .... Activate and choose ‘rotation’ as field. Without these settings the tool is inactive.

Angle

Gambar 12.34: Rotate Point Symbols

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To change the rotation, select a point feature in the map canvas and rotate it holding the left mouse button pressed. A red arrow with the rotation value will be visualized (see Figure_edit_4). When you release the left mouse button again, the value will be updated in the attribute table. Catatan: If you hold the Ctrl key pressed, the rotation will be done in 15 degree steps.

12.3.6 Creating new Vector layers QGIS allows to create new Shapefile layers, new SpatiaLite layers, and new GPX Layers. Creation of a new GRASS layer is supported within the GRASS-plugin. Please refer to section Creating a new GRASS vector layer for more information on creating GRASS vector layers. Creating a new Shapefile layer New Shapefile Layer... from the Layer menu. The To create a new Shape layer for editing, choose New → New Vector Layer dialog will be displayed as shown in Figure_edit_5. Choose the type of layer (point, line or polygon) and the CRS (Coordinate Reference System). Note that QGIS does not yet support creation of 2.5D features (i.e. features with X,Y,Z coordinates).

Gambar 12.35: Creating a new Shapefile layer Dialog To complete the creation of the new Shapefile layer, add the desired attributes by clicking on the [Add to attributes list] button and specifying a name and type for the attribute. A first ‘id’ column is added as default but can be removed, if not wanted. Only Type: real

, Type: integer

, Type: string

and Type:date

attributes are supported. Additionally and according to the attribute type you can also define the width and precision of the new attribute column. Once you are happy with the attributes, click [OK] and provide a name for the shapefile. QGIS will automatically add a .shp extension to the name you specify. Once the layer has been created, it will be added to the map and you can edit it in the same way as described in Section Digitizing an existing layer above.

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Creating a new SpatiaLite layer New SpatiaLite Layer... from the Layer menu. To create a new SpatiaLite layer for editing, choose New → The New SpatiaLite Layer dialog will be displayed as shown in Figure_edit_6.

Gambar 12.36: Creating a New SpatiaLite layer Dialog First step is to select an existing SpatiaLite database or to create a new SpatiaLite database. This can be done with the browse button

to the right of the database field. Then add a name for the new layer and define the layer

type and specify the Coordinate Reference System with [Specify CRS]. If desired you can select to autoincrementing primary key.

Create an

To define an attribute table for the new SpatiaLite layer, add the names of the attribute columns you want to create with the according column type and click on the [Add to attribute list] button. Once you are happy with the attributes, click [OK]. QGIS will automatically add the new layer to the legend and you can edit it in the same way as described in Section Digitizing an existing layer above. Further management of SpatiaLite-Layers can be done with the DB Manager see Plugin Pengelola DB. Creating a new GPX layer To create a new GPX file you need to load the GPS plugin first. Plugins → Plugin Manager Dialog. Activate the

Plugin Manager... opens the

GPS Tools checkbox.

When this plugin is loaded choose New → Create new GPX Layer... from the Layer. In the Save new GPX file as dialog you can choose where to save the new GPX layer.

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12.3.7 Working with the Attribute Table The attribute table displays features of a selected layer. Each row in the table represents one map feature and each column contains a particular piece of information about the feature. Features in the table can be searched, selected, moved or even edited. To open the attribute table for a vector layer, make the layer active by clicking on it in the map legend area. Then from the main menu Layer choose

Open Attribute Table. It is also possible to rightclick on the layer and

choose Open Attribute Table from the dropdown menu and to click on the the Attributes toolbar.

Open Attribute Table button in

This will open a new window which displays the feature attributes in the layer (figure_attributes_1). The number of features and the number of selected features are shown in the attribute table title.

Gambar 12.37: Attribute Table for regions layer

Selecting features in an attribute table Each selected row in the attribute table displays the attributes of a selected feature in the layer. If the set of features selected in the main window is changed, the selection is also updated in the attribute table. Likewise, if the set of rows selected in the attribute table is changed, the set of features selected in the main window will be updated. Rows can be selected by clicking on the row number on the left side of the row. Multiple rows can be marked by holding the Ctrl key. A continuous selection can be made by holding the Shift key and clicking on several row headers on the left side of the rows. All rows between the current cursor position and the clicked row are selected. Moving the cursor position in the attribute table, by clicking a cell in the table, does not change the row selection. Changing the selection in the main canvas does not move the cursor position in the attribute table. The table can be sorted by any column, by clicking on the column header. A small arrow indicates the sort order (downward pointing means descending values from the top row down, upward pointing means ascending values from the top row down). For a simple search by attributes on only one column choose the Column filter → from the menu in the bottom left corner. Select the field (column) from which the search should be performed from the dropdown menu and hit the [Apply] button. Then only the matching features are shown in the Attribute table. To make a selection you have to use the

Select features using an Expression

icon on top of the Attribute table. The

Select features using an Expression

Field Calculator allows you to define a subset of a table using a Function List like in the (see Field Calculator). The query result then can be saved as a new vector layer. For example if you want to find regions that are boroughs from the regions.shp of the QGIS sample data you have to open the >Fields and Values menu and choose the field that you want to query. Double-klick the field ‘TYPE_2’ and also [Load all unique values] . From list choose and double-klick ‘Borough’. In the Expression field the following query appears:

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"TYPE_2"

=

’Borough’

The matching rows will be selected and the total number of matching rows will appear in the title bar of the attribute table, and in the status bar of the main window. For searches that display only selected features on the map use the Query Builder described in Section Query Builder. To show selected records only, use Show Selected Features from the menu at the bottom left. The other buttons at the top of the attribute table window provide following functionality: •

Toggle editing mode

•

Save Edits

•

Unselect all

•

Move selected to top

•

Invert selection

•

Copy selected rows to clipboard

•

Zoom map to the selected rows

•

Pan map to the selected rows

•

Delete selected features

•

New Column

•

Delete Column

•

Open field calculator

to edit single values and to enable functionalities described below also with Ctrl+E

also with Ctrl+S also with Ctrl+U also with Ctrl+T

also with Ctrl+R also with Ctrl+C also with Ctrl+J

also with Ctrl+P

also with Ctrl+D

for PostGIS layers and for OGR layers with GDAL version >= 1.6 also with Ctrl+W for PostGIS layers and for OGR layers with GDAL version >= 1.9 also with Ctrl+L also with Ctrl+I

Tip: Skip WKT geometry Copy selected rows to clipboard If you want to use attribute data in external programs (such as Excel) use the button. You can copy the information without vector geometries if you deactivate Settings → Options → Data sources

menu

Copy geometry in WKT representation from attribute table.

Save selected features as new layer The selected features can be saved as any OGR supported vector format and also transformed into another Coordinate Reference System (CRS). Just open the right mouse menu of the layer and click on Save selection as → to define the name of the output file, its format and CRS (see Section Legenda Peta). It is also possible to specify OGR creation options within the dialog. Working with non spatial attribute tables QGIS allows also to load non spatial tables. This includes currently tables supported by OGR, delimited text as well as the PostgreSQL, MSSQL and Oracle provider. The tables can be used for field lookups or just generally browsed and edited using the table view. When you load the table you will see it in the legend field. It can be opened e.g. with the

Open Attribute Table

tool and is then editable like any other layer attribute table.

As an example you can use columns of the non spatial table to define attribute values or a range of values that are allowed to be added to a specific vector layer during digitizing. Have a closer look at the edit widget in section Fields Menu to find out more.

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12.4 Query Builder The Query Builder allows you to define a subset of a table using a SQL-like WHERE clause and display the result in the main window. The query result then can be saved as a new vector layer.

12.4.1 Query Open the Query Builder by opening the Layer Properties and go to the General menu. Under Feature subset click on the [Query Builder] button to open the Query builder. For example, if you have a regions layer with a TYPE_2 field you could select only regions that are borough in the Provider specific filter expression box of the Query builder. Figure_attributes_2 shows an example of the Query builder populated with the regions.shp layer from the QGIS sample data. The Fields, Values and Operators sections help the user to construct the SQL-like query.

Gambar 12.38: Query Builder The Fields list contains all attribute columns of the attribute table to be searched. To add an attribute column to the SQL where clause field, double click its name in the Fields list. Generally you can use the various fields, values and operators to construct the query or you can just type it into the SQL box. The Values list lists the values of an attribute table. To list all possible values of an attribute, select the attribute in the Fields list and click the [all] button. To list the first 25 unique values of an attribute column, select the attribute column in the Fields list and click the [Sample] button. To add a value to the SQL where clause field, double click its name in the Values list. The Operators section contains all usable operators. To add an operator to the SQL where clause field, click the appropriate button. Relational operators ( = , > , ...), string comparison operator (LIKE), logical operators (AND, OR, ...) are available. The [Test] button shows a message box with the number of features satisfying the current query, which is usable in the process of query construction. The [Clear] button clears the text in the SQL where clause text field. The [OK] button closes the window and selects the features satisfying the query. The [Cancel] button closes the window without changing the current selection.

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12.4.2 Save selected features as new layer The selected features can be saved as any OGR supported vector format and also transformed into another Coordinate Reference System (CRS). Just open the right mouse menu of the layer and click on Save selection as → to define the name of the output file, its format and CRS (see Section Legenda Peta). It is also possible to specify OGR creation options within the dialog.

12.5 Field Calculator Field Calculator button in the attribute table allows to perform calculations on basis of existing attribute The values or defined functions, e.g to calculate length or area of geometry features. The results can be written to a new attribute column or it can be used to update values in an already existing column.

You have to bring the vector layer in editing mode, before you can click on the field calculator icon to open the dialog (see figure_attributes_3). In the dialog you first have to select whether you want to only update selected features, create a new attribute field where the results of the calculation will be added or update an existing field.

Gambar 12.39: Field Calculator If you choose to add a new field, you need to enter a field name, a field type (integer, real or string), the total field width, and the field precision (see figure_attributes_3). For example, if you choose a field width of 10 and a field precision of 3 it means you have 6 signs before the dot, then the dot and another 3 signs for the precision. The Function List contains functions as well as fields and values. View the help function in the Selected Function Help. In Expression you see the calculation expressions you create with the Function List. The most commonly used operators, see Operators. In the Function List, click on Fields and Values to view all attributes of the attribute table to be searched. To add an attribute to the Field calculator Expression field, double click its name in the Fields and Values list. Generally you can use the various fields, values and functions to construct the calculation expression or you can just type it into the box. To display the values of a field, you just right click on the appropriate field. You can choose between Load top 10 unique values and Load all unique values. On the right side opens the Field Values list with the unique values. To add a value to the Field calculator Expression box, double click its name in the Field Values list. 108

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The Operators, Math, Conversions, String, Geometry and Record groups provides several functions. In Operators you find mathematical operators. Find Math for mathematical functions. The Conversions group contains functions that convert one data type to another. The String group provides functions for data strings. In the Geometry group you find functions for geometry objects. With Record group functions you can add a numeration to your data set. To add a function to the Field calculator Expression box, click on the > and then doubleclick the function. A short example illustrates how the field calculator works. We want to calculate the length in km of the railroads layer from the QGIS sample dataset: 1. Load the Shapefile railroads.shp in QGIS and press Toggle editing mode

2. Click on 3. Select the

and open the

Field Calculator

Open Attribute Table

.

dialog.

Create a new field checkbox to safe the calculations into a new field.

4. Add length as Output field name, real as Output field type and define Output field width 10 and a Precision of 3. 5. Now doubleclick on function $length in the Geometry group to add it into the Field calculator expression box. 6. Complete the expression by typing ‘’/ 1000” in the Field calculator expression box and click [Ok]. 7. You can now find a new column length in the attribute table. The available functions are listed below. The field calculator Function list with the Selected Function Help , Operators and Expression menu are also available through the rule-based rendering in the Style menu of the Layer properties and the expression based labeling

in the

Labeling

core application.

Operators This group contains operators e.g + - * a + b a - b a * b a / b a % b a ^ b a = b a > b a < b a b a != b a = b a ~ b + a - a || LIKE ILIKE

a plus b a minus b a multiplied by b a divided by b a modulo b for example 7 % 2 = 1 -> 2 fits into 7 three times rest is 1 a power b for example 2^2=4 or 2^3=8 a and b are equal a is larger than b a is smaller than b a and b are not equal a and b are not equal a is less than or equal to b a is larger than or equal to b a matches the regular expression b positive sign negative value of a joins two values together into a string ’Hello’ || ’ world’ returns 1 if the string matches the supplied pattern returns 1 if the string matches case-insensitive the supplied pattern. ILIKE can be used instead of LIKE to make the match case-insensitive IS returns 1 if a is the same as b OR returns 1 when condition a or b is true AND returns 1 when condition a and b are true NOT returns 1 if a is not the same as b column name "column name" value of the field column name ’string’ a string value NULL null value a IS NULL a has no value a IS NOT NULL a has a value

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a IN (value[,value]) a NOT IN (value[,value])

a is below the values listed a is not below the values listed

Conditionals This group contains functions to handle conditional checks in expressions. CASE CASE ELSE coalesce regexp_match

evaluates multiple expressions and return a result evaluates multiple expressions and return a result returns the first non-NULL value from the expression list returns true if any part of a string matches the supplied regular expression

Mathematical Functions This group contains math functions e.g square root, sin and cos sqrt(a) abs sin(a) cos(a) tan(a) asin(a) acos(a) atan(a) atan2(y,x) exp ln log10 log round rand randf max min clamp scale_linear scale_exp floor ceil $pi

square root of a returns the absolute value of a number. sinus of a cosinus of a tangens of a arcussinus of a arcuscosinus of a arcustangens of a arcustangens of y/x using the signs of the two arguments to determine the quadrant of the result exponential of an value value of the natural logarithm of the passed expression value of the base 10 logarithm of the passed expression value of the logarithm of the passed value and base number to number of decimal places random integer within the range specified by the minimum and maximum argument (inclusive) random float within the range specified by the minimum and maximum argument (inclusive) largest value in a set of values smallest value in a set of values restricts an input value to a specified range transforms a given value from an input domain to an output range using linear interpolation transforms a given value from an input domain to an output range using an exponential curve rounds a number downwards rounds a number upwards pi as value for calculations

Conversions This group contains functions to convert on data type to another e.g string to integer, integer to string. toint toreal tostring todatetime todate totime tointerval

converts a string to integer number converts a string to real number convert number to string convert a string into Qt data time type convert a string into Qt data type convert a string into Qt time type converts a string to a interval type. Can be used to take days, hours, month, etc off a date

Date and Time Functions This group contains functions for handling date and time data.

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$now age year month week day hour minute second

current date and time difference between two dates extract the year part from a date, or the number of years from a Interval extract the month part from a date, or the number of months from a Interval extract the week number from a date, or the number of weeks from a Interval extract the day from a date, or the number of days from a Interval extract the hour from a datetime or time, or the number of hours from a Interval extract the minute from a datetime or time, or the number of minutes from a Interval extract the second from a datetime or time, or the number of minutes from a Interval

String Functions This group contains functions that operate on strings e.g replace, convert to upper case. lower upper title

convert string a to lower case convert string a to upper case converts all words of a string to title case (all words lower case with leading capital letter) trim removes all leading and trailing whitespace (spaces, tabs, etc) from a string length length of string a replace returns a string with the the supplied string replaced regexp_replace(a,this,that) returns a string with the supplied regular expression replaced regexp_substr returns the portion of a string which matches a supplied regular expression substr(*a*,from,len) returns a part of a string concat concatenates several strings to one strpos returns the index of a regular expression in a string left returns a substring that contains the n leftmost characters of the string right returns a substring that contains the n rightmost characters of the string rpad returns a string with supplied width padded using the fill character lpad returns a string with supplied width padded using the fill character format formats a string using supplied arguments format_number returns a number formatted with the locale separator for thousands. Also truncates the number to the number of supplied places format_date formats a date type or string into a custom string format

Color Functions This group contains functions for manipulating colors. color_rgb color_rgba ramp_color color_hsl color_hsla color_hsv color_hsva color_cmyk color_cmyka

returns a string representation of a color based on its and blue components returns a string representation of a color based on its blue, and alpha (transparency) components returns a string representing a color from a color ramp returns a string representation of a color based on its saturation, and lightness attributes returns a string representation of a color based on its lightness and alpha (transparency) attributes returns a string representation of a color based on its saturation, and value attributes returns a string representation of a color based on its value and alpha (transparency) attributes returns a string representation of a color based on its yellow and black components returns a string representation of a color based on its yellow, black and alpha (transparency) components

red, green, red, green,

hue, hue, saturation, hue, hue, saturation, cyan, magenta, cyan, magenta,

Geometry Functions This group contains functions that operate on geometry objects e.g length, area.

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xat yat $area $length $perimeter $x $y $geometry geomFromWKT geomFromGML bbox disjoint intersects touches crosses contains overlaps within buffer centroid convexHull difference distance intersection symDifference combine union geomToWKT

retrieves a x coordinate of the current feature retrieves a y coordinate of the current feature returns the area size of the current feature returns the area size of the current feature returns the perimeter length of the current feature returns the x coordinate of the current feature returns the y coordinate of the current feature returns the geometry of the current feature. Can be used for processing with other functions. returns a geometry created from a Well-Known Text (WKT) representation. returns a geometry from a GML representation of geometry returns 1 if the Geometries do not share any space together returns 1 if the geometries spatially intersect (share any portion of space) and 0 if they don’t returns 1 if the geometries have at least one point in common, but their interiors do not intersect returns 1 if the supplied geometries have some, but not all, interior points in common. returns true if and only if no points of b lie in the exterior of a, and at least one point of the interior of b lies in the interior of a returns 1 if the Geometries share space, are of the same dimension, but are not completely contained by each other. returns 1 if the geometry a is completely inside geometry b returns a geometry that represents all points whose distance from this geometry is less than or equal to distance returns the geometric center of a geometry returns the convex hull of a geometry. It represents the minimum convex geometry that encloses all geometries within the set returns a geometry that represents that part of geometry a that does not intersect with geometry a returns the minimum distance (based on spatial ref) between two geometries in projected units returns a geometry that represents the shared portion of geometry a and geometry b returns a geometry that represents the portions of a and b that do not intersect returns the combination of geometry a and geometry b returns a geometry that represents the point set union of the geometries returns the Well-Known Text (WKT) representation of the geometry without SRID metadata

Record Functions This group contains functions that operate on record identifiers. $rownum $id $scale

returns the number of the current row returns the feature id of the current row returns the current scale of the map canvas

Fields and Values Contains a list of fields from the layer. Sample values can also be accessed via right-click. Select the field name from the list then right-click to access context menu with options to load sample values from the selected field.

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BAB 13

Pekerjaan dengan Data Raster

13.1 Working with Raster Data This Section describes how to visualize and set raster layer properties. QGIS uses the GDAL library to read and write raster data formats, including Arc/Info Binary Grid, Arc/Info ASCII Grid, GeoTIFF, Erdas Imagine and many more. GRASS raster support is supplied by a native QGIS data provider plugin. The raster data can also be loaded in read mode from zip and gzip archives into QGIS. At the date of this document, more than 100 raster formats are supported by the GDAL library (see GDAL-SOFTWARE-SUITE Literatur dan Referensi Web). A complete list is available at http://www.gdal.org/formats_list.html. Catatan: Not all of the listed formats may work in QGIS for various reasons. For example, some require external commercial libraries or the GDAL installation of your OS was not built to support the format you want to use. Only those formats that have been well tested will appear in the list of file types when loading a raster into QGIS. Other untested formats can be loaded by selecting the [GDAL] All files (*) filter. Working with GRASS raster data is described in Section GRASS GIS Integration.

13.1.1 What is raster data? Raster data in GIS are matrices of discrete cells that represent features on, above or below the earth’s surface. Each cell in the raster grid is the same size, and cells are usually rectangular (in QGIS they will always be rectangular). Typical raster datasets include remote sensing data such as aerial photography or satellite imagery and modelled data such as an elevation matrix. Unlike vector data, raster data typically do not have an associated database record for each cell. They are geocoded by its pixel resolution and the x/y coordinate of a corner pixel of the raster layer. This allows QGIS to position the data correctly in the map canvas. QGIS makes use of georeference information inside the raster layer (e.g. GeoTiff) or in an appropriate world file to properly display the data.

13.1.2 Loading raster data in QGIS Add Raster Layer Raster layers are loaded either by clicking on the icon or by selecting the Layer → Add Raster Layer menu option. More than one layer can be loaded at the same time by holding down the Control or Shift key and clicking on multiple items in the dialog Open a GDAL Supported Raster Data Source.

Once a raster layer is loaded in the map legend you can click on the layer name with the right mouse button to select and activate layer specific features or to open a dialog to set raster properties for the layer. Right mouse button menu for raster layers

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• Zoom to layer extent • Zoom to Best Scale (100%) • Show in Overview • Remove • Duplicate • Set Layer CRS • Set Project CRS from Layer • Save as ... • Properties • Rename • Copy Style • Add New Group • Expand all • Collapse all • Update Drawing Order

13.2 Raster Properties Dialog To view and set the properties for a raster layer, double click on the layer name in the map legend or right click on the layer name and choose Properties from the context menu: This will open the Raster Layer Properties dialog, (see figure_raster_1). There are several menus in the dialog: • General • Style • Transparency • Pyramids • Histogram • Metadata

13.2.1 General Menu Layer Info The General menu displays basic information about the selected raster, including the layer source path, the display name in the legend (which can be modified) and the number of columns, rows and No-Data Values of the raster. Coordinate reference system Below you find the coordinate reference system (CRS) information printed as a PROJ.4-string. If this setting is not correct, it can be modified by clicking the [Specify] button.

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Gambar 13.1: Raster Layers Properties Dialog Scale Dependent visibility Additionally Scale Dependent visibility can be set in this tab. You need to check the checkbox and set an appropriate scale where your data will be displayed in the map canvas. At the bottom you can see a thumbnail of the layer, its legend symbol, and the palette.

13.2.2 Style Menu Band rendering QGIS offers four different Render types. The renderer chosen is dependent on the data type. 1. Multiband color - if the file comes as a multi band with several bands (e.g. used with a satellite image with several bands) 2. Paletted - if a single band file comes with an indexed palette (e.g. used with a digital topographic map) 3. Singleband gray- (one band of) the image will be rendered as gray, QGIS will choose this renderer if the file neither has multi bands, nor has an indexed palette nor has a continous palette (e.g. used with a shaded relief map) 4. Singleband pseudocolor - this renderer is possible for files with a continuous palette, e.g. the file has got a color map (e.g. used with an elevation map) Multiband color With the multiband color renderer three selected bands from the image will be rendered, each band representing the red, green or blue component that will be used to create a color image. You can choose several Contrast enhancement methods: ‘No enhancement’, ‘Stretch to MinMax’, ‘Stretch and clip to MinMax’ and ‘Clip to min max’. This selection offers you a wide range of options to modify the appearance of your rasterlayer. First of all you have to get the data range from your image. This can be done by choosing the Extent and pressing [Load]. QGIS can Estimate (faster) the Min and Max values of the bands or use the Actual (slower) Accuracy.

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Gambar 13.2: Raster Renderer - Multiband color Now you can scale the colors with the help of the Load min/max values section. A lot of images have few very low and high data. These outliers can be eliminated using the Cumulative count cut setting. The standard data range is set from 2% until 98% of the data values and can be adapted manually. With this setting the gray character Min/max QGIS creates a color table with the whole data of the image can disappear. With the scaling option included in the original image. E.g. QGIS creates a color table with 256 values, given the fact that you have 8bit bands. You can also calculate your color table using the Mean +/- standard deviation x . Then only the values within the standard deviation or within multiple standard deviations are considered for the color table. This is useful when you have one or two cells with abnormally high values in a raster grid that are having a negative impact on the rendering of the raster. All calculation can also be made for the

Current extend.

Tip: Viewing a Single Band of a Multiband Raster If you want to view a single band (for example Red) of a multiband image, you might think you would set the Green and Blue bands to “Not Set”. But this is not the correct way. To display the Red band, set the image type to ‘Singleband gray’, then select Red as the band to use for Gray. Paletted This is the standard render option for singleband files that already include a color table, where each pixel value is assigned to a certain color. In that case, the palette is rendered automatically. If you want to change colors assigned to certain values, just double-click on the color and the Select color dialog appears.

Gambar 13.3: Raster Renderer - Paletted Contrast enhancement Catatan: When adding GRASS rasters the option Contrast enhancement will be always set to automatically to stretch to min max regardless if the QGIS general options this is set to another value. Singleband gray This renderer allows you to render a single band layer with a Color gradient ‘Black to white’ or ‘White to black’. You can define a Min and a Max value with choosing the Extend first and then pressing [Load]. QGIS can 116

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Estimate (faster) the Min and Max values of the bands or use the

Actual (slower) Accuracy.

Gambar 13.4: Raster Renderer - Singleband gray With the Load min/max values section scaling of the color table is possible. Outliers can be eliminated using the Cumulative count cut setting. The standard data range is set from 2% until 98% of the data values and can be adapted manually. With this setting the gray character of the image can disappear. Further settings can be made with Min/max and Mean +/- standard deviation x . While the first one creates a color table with the whole data included in the original image the second creates a colortable that only considers values within the standard deviation or within multiple standard deviations. This is useful when you have one or two cells with abnormally high values in a raster grid that are having a negative impact on the rendering of the raster. Singleband pseudocolor This is a render option for single band files including a continous palette. You can also create individual color maps for the single bands here. Three types of color interpolation are available:

Gambar 13.5: Raster Renderer - Singleband pseudocolor 1. Discrete 2. Linear 3. Exact In the left block the button

Add values manually

adds a value to the individual color table.

Remove selected row

Button

Sort colormap items

deletes a value from the individual color table and the button sorts the color table according to the pixel values in the value column. Double clicking on the value-column lets you insert a specific value. Double clicking on the color-column opens the dialog Change color where you can select a color to apply on that value. Further you can also add labels for each color but this value won’t be displayed when you use the identify feature tool. You can also click on the button

13.2. Raster Properties Dialog

Load color map from band

, which tries to load the table

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Load color map from file from the band (if it has any). And you can use the buttons or an existing color table or to save the defined color table for other sessions.

Export color map to file

to load

In the right block Generate new color map allows you to create newly categorized colormaps. For the Classification mode

‘Equal interval’ you only need to select the number of classes

Classify. You can invert the colors of the the color map by clicking the

and press the button

Invert checkbox. In case of the Mode

‘Continous’ QGIS creates classes depending on the Min and Max automatically. Defining Min/Max values can be done with the help of Load min/max values section. A lot of images have few very low and high data. Cumulative count cut setting. The standard data range is set from These outliers can be eliminated using the 2% until 98% of the data values and can be adapted manually. With this setting the gray character of the image can disappear. With the scaling option Min/max QGIS creates a color table with the whole data included in the original image. E.g. QGIS creates a color table with 256 values, given the fact that you have 8bit bands. You can also calculate your color table using the Mean +/- standard deviation x . Then only the values within the standard deviation or within multiple standard deviations are considered for the color table. Color rendering For every Band rendering a Color rendering is possible. You can achieve special rendering effects for your raster file(s) using one one of the blending modes (see blend_modes). Further settings can be made in modifiying the Brightness, the Saturation and the Contrast. You can use a Grayscale option where you can choose between ‘By lightness’, ‘By luminosity’ and ‘By average’. For one hue in the color table you can modiy the ‘Strength’. Resampling The Resampling option makes it appearance when you zoom in and out of the image. Resampling modes can optimize the appearance of the map. They calculate a new gray value matrix through a geometric transformation. While applying the ‘Nearest neighbour’ method the map can have a pixelated structure when zooming in. This appearance can be improved by using the ‘Bilinear’ or ‘Cubic’ method. Sharp features are caused to be blurred now. The effect is a smoother image. The method can be applied e.g. to digital topographic raster maps.

13.2.3 Transparency Menu QGIS has the ability to display each raster layer at varying transparency levels. Use the transparency slider to indicate to what extent the underlying layers (if any) should be visible though the current raster layer. This is very useful, if you like to overlay more than one rasterlayer, e.g. a shaded relief map overlayed by a classified rastermap. This will make the look of the map more three dimensional. Additionally you can enter a rastervalue, which should be treated as NODATA in the Additional no data value menu. An even more flexible way to customize the transparency can be done in the Custom transparency options section. The transparency of every pixel can be set here. As an example we want to set the water of our example raster file landcover.tif to a transparency of 20 %. The following steps are neccessary: 1. Load the rasterfile landcover. 2. Open the Properties dialog by double-clicking on the raster name in the legend or by right-clicking and choosing Properties from the popup menu. 3. Select the Transparency menu 4. From the Transparency band menu choose ‘None’.

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5. Click the

Add values manually

button. A new row will appear in the pixel-list.

6. Enter the raster-value (we use 0 here) in the ‘From’ and ‘To’ column and adjust the transparency to 20 %. 7. Press the [Apply] button and have a look at the map. You can repeat the steps 5 and 6 to adjust more values with custom transparency. As you can see this is quite easy to set custom transparency, but it can be quite a lot of work. Therefore you Export to file to save your transparency list to a file. The button can use the button transparency settings and applies them to the current raster layer.

Import from file

loads your

13.2.4 Pyramids Menu Large resolution raster layers can slow navigation in QGIS. By creating lower resolution copies of the data (pyramids), performance can be considerably improved as QGIS selects the most suitable resolution to use depending on the level of zoom. You must have write access in the directory where the original data is stored to build pyramids. Several resampling methods can be used to calculate the pyramids: • Nearest Neighbour • Average • Gauss • Cubic • Mode • None If you choose ‘Internal (if possible)’ from the Overview format menu QGIS tries to build pyramids internally. You can also choose ‘External’ and ‘External (Erdas Imagine)’. Please note that building pyramids may alter the original data file and once created they cannot be removed. If you wish to preserve a ‘non-pyramided’ version of your raster, make a backup copy prior to building pyramids.

13.2.5 Histogram Menu The Histogram menu allows you to view the distribution of the bands or colors in your raster. It is generated automatically when you open the Histogram menu. All existing bands will be displayed together. You can save the histogram as an image with the button. With the Visibility option in the Prefs/Actions menu you can display histograms of the individual bands. You will need to select the option Show selected band. The Min/max options allow you to ‘Always show min/max markers’, to ‘Zoom to min/max’ and to ‘Update style to min/max’. With the Actions option you can ‘Reset’ and ‘Recompute histogram’ after you have chosen the Min/max options.

13.2.6 Metadata Menu The Metadata menu displays a wealth of information about the raster layer, including statistics about each band in the current raster layer. From this menu entries are made for the Description, Attribution, MetadataUrl and Properties. In Properties statistics are gathered on a ‘need to know’ basis, so it may well be that a given layers statistics have not yet been collected.

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13.3 Raster Calculator The Raster Calculator in the Raster menu (see figure_raster_2) allows to perform calculations on basis of existing raster pixel values. The results are written to a new raster layer with a GDAL supported format.

Gambar 13.6: Raster Calculator The Raster bands list contains all loaded raster layers that can be used. To add a raster to the raster calculator expression field, double click its name in the Fields list. You can then use the operators to construct calculation expressions or you can just type it into the box. In the Result layer section you have to define an output layer. You can then define the extent of the calculation area based on an input raster layer or based on X,Y coordinates and on Columns and Rows to set the resolution of the output layer. If the input layer has a different resolution, the values will be resampled with nearest neighbor algorithm. The Operators section contains all usable operators. To add an operator to the raster calculator expression box, click the appropriate button. Mathematical calculations (+, -, *, ... ) and trigonometric functions (sin, cos, tan, ... ) are available. Stay tuned for more operators to come! With the Add result to project checkbox the result layer will automatically added to the legend area and can be visualized.

13.3.1 Examples Convert elevation values from meter to feet Creating an elevation raster feet from a raster in meter, you need to use the conversion factor for meters to feet: 3.28. The expression is: elevation@1 * 3.28

Using a mask If you want to mask out parts of a raster, because you are only interested in elevations above 0 meter, you can use following expression to create a mask and apply the result to a raster in one step. (elevation@1 >= 0) * elevation@1

For every cell greater than or equal to 0, set its value to 1, otherwise set it to 0. This creates the mask on the fly. 120

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14.1 QGIS as OGC Data Client The Open Geospatial Consortium (OGC), is an international organization with more than 300 commercial, governmental, nonprofit and research organizations worldwide. Its members develop and implement standards for geospatial content and services, GIS data processing and exchange. Describing a basic data model for geographic features an increasing number of specifications are developed to serve specific needs for interoperable location and geospatial technology, including GIS. Further information can be found under http://www.opengeospatial.org/. Important OGC specifications supported by QGIS are: • WMS — Web Map Service (WMS/WMTS Client) • WMTS — Web Map Tile Service (WMS/WMTS Client) • WFS — Web Feature Service (WFS and WFS-T Client) • WFS-T — Web Feature Service - Transactional (WFS and WFS-T Client) • WCS — Web Coverage Service (WCS Client) • SFS — Simple Features for SQL (PostGIS Layers) • GML — Geography Markup Language OGC services are increasingly being used to exchange geospatial data between different GIS implementations and data stores. QGIS can deal with the above specifications as a client, being SFS (through support of the PostgreSQL / PostGIS data provider, see Section PostGIS Layers).

14.1.1 WMS/WMTS Client Overview of WMS Support QGIS currently can act as a WMS client that understands WMS 1.1, 1.1.1 and 1.3 servers. It has particularly been tested against publicly accessible servers such as DEMIS. WMS servers act upon requests by the client (e.g. QGIS) for a raster map with a given extent, set of layers, symbolization style, and transparency. The WMS server then consults its local data sources, rasterizes the map, and sends it back to the client in a raster format. For QGIS this would typically be JPEG or PNG. WMS is generically a REST (Representational State Transfer) service rather than a fully-blown Web Service. As such, you can actually take the URLs generated by QGIS and use them in a web browser to retrieve the same images that QGIS uses internally. This can be useful for troubleshooting, as there are several brands of WMS servers in the market and they all have their own interpretation of the WMS standard. WMS layers can be added quite simply, as long as you know the URL to access the WMS server, you have a serviceable connection to that server, and the server understands HTTP as the data transport mechanism.

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Overview of WMTS Support QGIS can also act as a WMTS client. WMTS is an OGC standard for distributing tile sets of geospatial data. This is a faster and a more efficient way of distributing data than WMS because with WMTS the tile sets are pre-generated and the client only requests the transmission of the tiles and not their production. A WMS request typically involves both the generation and transmission of the data. A well known example of a non-OGC standard for viewing tiled geospatial data is Google Maps. In order to display the data at a variety of scales close to what the user might want, the WMTS tile sets are produced at several different scale levels and are made available for the GIS client to request them. This diagram illustrates the concept of tile sets:

Gambar 14.1: Concept of WMTS tile sets The two types of WMTS interfaces that QGIS supports are via Key-Value-Pairs (KVP) and RESTful. These two interfaces are different and you need to specify them to QGIS differently. 1) In order to access a WMTS KVP service, a QGIS user opens the WMS/WMTS interface and adds the following string to the URL of the WMTS tile service: "?SERVICE=WMTS&REQUEST=GetCapabilities"

An example of this type of address is http://opencache.statkart.no/gatekeeper/gk/gk.open_wmts?\ service=WMTS&request=GetCapabilities

For testing the topo2 layer in this WMTS works nicely. Adding this string indicates that a WMTS web service is to be used instead of a WMS service 2) The RESTful WMTS service takes a different form, it is a straightforward URL, the format recommended by the OGC is: {WMTSBaseURL}/1.0.0/WMTSCapabilities.xml

This format helps you to recognize that it is a RESTful address. A RESTful WMTS is accessed in QGIS by simply adding its address in the WMS setup in the URL field of the form. An example for an Austrian basemap of this type of address is http://maps.wien.gv.at/basemap/1.0.0/WMTSCapabilities.xml Catatan: You can find some old service call WMS-C. Thoses services are quiet similar to WMTS service same purpose but working a little bit differently). You can manage them as the same way you do it for WMTS services. Just add ?tiled=true at the end of the url. See http://wiki.osgeo.org/wiki/Tile_Map_Service_Specification for more information about this specification. When you read WMTS you can often think WMS-C also.

Selecting WMS/WMTS Servers The first time you use the WMS feature, there are no servers defined.

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Begin by clicking the

Add WMS layer

button inside the toolbar, or through the Layer → Add WMS Layer... menu.

The dialog Add Layer(s) from a Server for adding layers from the WMS server appears. You can add some servers to play with by clicking the [Add default servers] button. This will add two WMS demo servers for you to use, the WMS servers of the DM Solutions Group and Lizardtech. To define a new WMS server in the tab Layers, select the [New] button. Then enter the parameters to connect to your desired WMS server, as listed in table_OGC_1: Name A name for this connection. This name will be used in the Server Connections drop-down box so that you can distinguish it from other WMS Servers. URL URL of the server providing the data. This must be a resolvable host name; the same format as you would use to open a telnet connection or ping a host. Username Username to access a secured WMS-server. This parameter is optional. Password Password for a basic authenticated WMS-server. This parameter is optional. Ignore GetMap URI

Ignore GetMap URI reported in capabilities, use given URI from URL-field above.

Ignore GetFeatureInfo URI

Ignore GetFeatureInfo URI reported in capabilities , use given URI from URL-field above

Table OGC 1: WMS Connection Parameters If you need to set up a proxy-server to be able to receive WMS-services from the internet, you can add your proxy-server in the options. Choose menu Settings → Options and click on the tab Network & Proxy. There you can add your proxy-settings and enable them by setting the select the correct proxy type from the Proxy type

Use proxy for web access. Make sure that you

dropdown menu.

Once the new WMS Server connection has been created, it will be preserved for future QGIS sessions. Tip: On WMS Server URLs Be sure, when entering in the WMS server URL, that you have the base URL. For example, you shouldn’t have fragments such as request=GetCapabilities or version=1.0.0 in your URL.

Loading WMS/WMTS Layers Once you have successfully filled in your parameters you can use the [Connect] button to retrieve the capabilities of the selected server. This includes the Image encoding, Layers, Layer Styles and Projections. Since this is a network operation, the speed of the response depends on the quality of your network connection to the WMS server. While downloading data from the WMS server, the download progress is visualized in the left bottom of the WMS dialog. Your screen should now look a bit like figure_OGR_1, which shows the response provided by the DM Solutions Group WMS server. Image Encoding The Image encoding section now lists the formats that are supported by both the client and server. Choose one depending on your image accuracy requirements. Tip: Image Encoding You will typically find that a WMS server offers you the choice of JPEG or PNG image encoding. JPEG is a lossy compression format, whereas PNG faithfully reproduces the raw raster data. Use JPEG if you expect the WMS data to be photographic in nature and/or you don’t mind some loss in picture quality. This trade-off typically reduces by 5 times the data transfer requirement compared to PNG. Use PNG if you want precise representations of the original data, and you don’t mind the increased data transfer requirements. Options

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Gambar 14.2: Dialog for adding a WMS server, showing its available layers The Options field provides a text field where you can add a Layer name for the WMS-layer. This name will be presented in the legend after loading the layer. Below the layer name you can define Tile size, if you want to set tile sizes (eg. 256x256) to split up the WMS request into multiple requests. The Feature limit for GetFeatureInfo defines what features from the server to query. If you select a WMS from the list a field with the default projection, provided by the mapserver, appears. If the [Change...] button is active, you can click on it and change the default projection of the WMS to another CRS, provided by the WMS server. Layer Order The tab Layer Order lists the selected layers available from the current connected WMS server. You may notice that some layers are expandable, this means that the layer can be displayed in a choice of image styles. You can select several layers at once, but only one image style per layer. When several layers are selected, they will be combined at the WMS Server and transmitted to QGIS in one go. Tip: WMS Layer Ordering WMS layers rendered by a server are overlaid in the order listed in the Layers section, from top to bottom of the list. If you want to change the overlay order, you can use the tab Layer Order. Transparency In this version of QGIS, the Global transparency setting from the Layer Properties is hard-coded to be always on, where available. Tip: WMS Layer Transparency The availability of WMS image transparency depends on the image encoding used: PNG and GIF support transparency, whilst JPEG leaves it unsupported. Coordinate Reference System

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A Coordinate Reference System (CRS) is the OGC terminology for a QGIS Projection. Each WMS Layer can be presented in multiple CRSs, depending on the capability of the WMS server. To choose a CRS, select [Change...] and a dialog similar to Figure Projection 3 in Working with Projections will appear. The main difference with the WMS version of the screen is that only those CRSs supported by the WMS Server will be shown. Server search Within QGIS you can search for WMS-servers. Figure_OGC_2 shows the tab Server Search with the Add Layer(s) from a Server dialog.

Gambar 14.3: Dialog for searching WMS servers after some keywords As you can see it is possible to enter a search-string in the text field and hit the [Search] button. After a short while the search result will be populated into the list below the text field. Browse the result list and inspect your search results within the table. To visualize the results, select a table entry, press the [Add selected row to WMS-list] button and change back to the tab Layers. QGIS automatically has updated your server list and the selected search result is already enabled in the list of saved WMS-servers in the Layers tab. You only need to request the list of layers by clicking the [Connect] button. This option is quite handy when you want to search maps by specific keywords. Basically this option is a frontend to the API of http://geopole.org. Tilesets When using WMTS (Cached WMS) Services like http://opencache.statkart.no/gatekeeper/gk/gk.open_wmts?\ service=WMTS&request=GetCapabilities

you are able to browse through the tab Tilesets given by the server. Additional information like tile size, formats and supported CRS are listed in this table. In combination with this feature you can use the tile scale slider from the Settings → Panels (KDE and Windows) or View → Panels (Gnome and MacOSX) then choose Tile scale, which gives you the available scales from the tileserver with nice slider docked in.

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Using the Identify Tool Once you have added a WMS server, and if any layer from a WMS server is queryable, you can then use the Identify tool to select a pixel on the map canvas. A query is made to the WMS server for each selection made. The results of the query are returned in plain text. The formatting of this text is dependent on the particular WMS server used. Format selection If multiple output formats are supported by the server, a combo box with supported formats is automatically added to the identify results dialog and the selected format will is stored in project for the layer. GML format support Identify tool supports WMS server response (GetFeatureInfo) in GML (it is called Feature in QGIS GUI The in this context) format. If “Feature” format is supported by the server and selected, results of the Identify tool are vector features like from regular vector layer. When a single feature is selected in the tree, it is highlighted in the map and it can be copied to clipboard and pasted to another vector layer. See example setup of UMN Mapserver below to support GetFeatureInfo GML format.

# in layer METADATA add which fields should be included and define geometry (example): "gml_include_items" "ows_geometries" "ows_mygeom_type"

"all" "mygeom" "polygon"

# Then there are two possibilities/formats available, see a) and b): # a) basic (output is generated by Mapserver and does not contain XSD) # in WEB METADATA define formats (example): "wms_getfeatureinfo_formatlist" "application/vnd.ogc.gml,text/html" # b) using OGR (output is generated by OGR, it is send as multipart and contains XSD) # in MAP define OUTPUTFORMAT (example): OUTPUTFORMAT NAME "OGRGML" MIMETYPE "ogr/gml" DRIVER "OGR/GML" FORMATOPTION "FORM=multipart" END # in WEB METADATA define formats (example): "wms_getfeatureinfo_formatlist" "OGRGML,text/html"

Viewing Properties Once you have added a WMS server, you can view its properties by right-clicking on it in the legend, and selecting Properties. Metadata Tab The tab Metadata displays a wealth of information about the WMS server, generally collected from the Capabilities statement returned from that server. Many definitions can be cleaned by reading the WMS standards (see OPEN-GEOSPATIAL-CONSORTIUM Literatur dan Referensi Web), but here are a few handy definitions: • Server Properties – WMS Version — The WMS version supported by the server. – Image Formats — The list of MIME-types the server can respond with when drawing the map. QGIS supports whatever formats the underlying Qt libraries were built with, which is typically at least image/png and image/jpeg. – Identity Formats — The list of MIME-types the server can respond with when you use the Identify tool. Currently QGIS supports the text-plain type. • Layer Properties – Selected — Whether or not this layer was selected when its server was added to this project.

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– Visible — Whether or not this layer is selected as visible in the legend. (Not yet used in this version of QGIS.) – Can Identify — Whether or not this layer will return any results when the Identify tool is used on it. – Can be Transparent — Whether or not this layer can be rendered with transparency. This version of QGIS will always use transparency if this is Yes and the image encoding supports transparency – Can Zoom In — Whether or not this layer can be zoomed in by the server. This version of QGIS assumes all WMS layers have this set to Yes. Deficient layers may be rendered strangely. – Cascade Count — WMS servers can act as a proxy to other WMS servers to get the raster data for a layer. This entry shows how many times the request for this layer is forwarded to peer WMS servers for a result. – Fixed Width, Fixed Height — Whether or not this layer has fixed source pixel dimensions. This version of QGIS assumes all WMS layers have this set to nothing. Deficient layers may be rendered strangely. – WGS 84 Bounding Box — The bounding box of the layer, in WGS 84 coordinates. Some WMS servers do not set this correctly (e.g. UTM coordinates are used instead). If this is the case, then the initial view of this layer may be rendered with a very ‘zoomed-out’ appearance by QGIS. The WMS webmaster should be informed of this error, which they may know as the WMS XML elements LatLonBoundingBox, EX_GeographicBoundingBox or the CRS:84 BoundingBox. – Available in CRS — The projections that this layer can be rendered in by the WMS server. These are listed in the WMS-native format. – Available in style — The image styles that this layer can be rendered in by the WMS server. WMS Client Limitations Not all possible WMS Client functionality had been included in this version of QGIS. Some of the more notable exceptions follow. Editing WMS Layer Settings Add WMS layer procedure, there is no ability to change the settings. A workaround is Once you’ve completed the to delete the layer completely and start again.

WMS Servers Requiring Authentication Currently public accessible and secured WMS-services are supported. The secured WMS-servers can be accessed by public authentication. You can add the (optional) credentials when you add a WMS-server. See section Selecting WMS/WMTS Servers for details. Tip: Accessing secured OGC-layers If you need to access secured layers with other secured methods than basic authentication, you could use InteProxy as a transparent proxy, which does support several authentication methods. More information can be found at the InteProxy manual found on the website http://inteproxy.wald.intevation.org. Tip: |qg| WMS Mapserver From Version 1.7.0 QGIS has its own implementation of a WMS 1.3.0 Mapserver. Read more about this at chapter QGIS as OGC Data Server.

14.1.2 WCS Client A Web Coverage Service (WCS) provides access to raster data in forms that are useful for client-side rendering, as input into scientific models, and for other clients. The WCS may be compared to the WFS and the WMS.

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As WMS and WFS service instances, a WCS allows clients to choose portions of a server’s information holdings based on spatial constraints and other query criteria. QGIS has a native WCS provider and supports both version 1.0 and 1.1 (which are significantly different), but currently it prefers 1.0, because 1.1 has many issues, each server implements it in different way with various particularities. The native WCS provider handles all network requests and uses all standard QGIS network settings (especially proxy). It is also possible select cache mode (always cache, prefer cache, prefer network, always network) and the provider also supports selection of time position if temporal domain is offered by server.

14.1.3 WFS and WFS-T Client In QGIS, a WFS layer behaves pretty much like any other vector layer. You can identify and select features and view the attribute table. Since QGIS 1.6 editing (WFS-T) is also supported. In general adding a WFS layer is very similar to the procedure used with WMS. The difference is there are no default servers defined, so we have to add our own. Loading a WFS Layer As an example we use the DM Solutions WFS server and display a layer. http://www2.dmsolutions.ca/cgi-bin/mswfs_gmap 1. Click on the

Add WFS Layer

The URL is:

tool on the Layers toolbar, the dialog Add WFS Layer from a Server appears

2. Click on [New] 3. Enter ‘DM Solutions’ as name 4. Enter the URL (see above) 5. Click [OK] 6. Choose ‘DM Solutions’ from the dropdown list Server Connections 7. Click [Connect] 8. Wait for the list of layers to be populated 9. Select the Parks layer in the list 10. Click [Apply] to add the layer to the map Note that proxy settings you have set in your preferences are also recognized.

Gambar 14.4: Adding a WFS layer You’ll notice the download progress is visualized in the left bottom of the QGIS main window. Once the layer is loaded, you can identify and select a province or two and view the attribute table.

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Only WFS 1.0.0 is supported. At this point there have not been many tests against WFS versions implemented in other WFS-servers. If you encounter problems with any other WFS-server, please do not hesitate to contact the development team. Please refer to Section Bantuan dan Dukungan for further information about the mailinglists. Tip: Finding WFS Servers You can find additional WFS servers by using Google or your favorite search engine. There are a number of lists with public URLs, some of them maintained and some not.

14.2 QGIS as OGC Data Server QGIS Server is an open source WMS 1.3 and WFS 1.0.0 implementation which, in addition, implements advanced cartographic features for thematic mapping. The QGIS Server is a FastCGI/CGI (Common Gateway Interface) application written in C++ that works together with a webserver (e.g. Apache, Lighttpd). It is funded by the EU projects Orchestra, Sany and the city of Uster in Switzerland. It uses QGIS as backend for the GIS logic and for map rendering. Furthermore the Qt library is used for graphics and for platform independent C++ programming. In contrast to other WMS software, the QGIS Server uses cartographic rules as a configuration language, both for the server configuration and for the user-defined cartographic rules. Moreover, the QGIS Server project provides the ‘Publish to Web’ plugin, a plugin for QGIS desktop which exports the current layers and symbology as a web project for QGIS Server (containing cartographic visualization rules expressed in SLD). As QGIS desktop and QGIS Server use the same visualization libraries, the maps that are published on the web look the same as in desktop GIS. The ‘Publish to Web’ plugin currently supports basic symbolization, with more complex cartographic visualization rules introduced manually. As the configuration is performed with the SLD standard and its documented extensions, there is only one standardised language to learn, which greatly simplifies the complexity of creating maps for the Web. In one of the following manuals we will provide a sample configuration to set up a QGIS Server. But for now we recommend to read one of the following URLs to get more information: • http://karlinapp.ethz.ch/qgis_wms/ • http://hub.qgis.org/projects/quantum-gis/wiki/QGIS_Server_Tutorial • http://linfiniti.com/2010/08/qgis-mapserver-a-wms-server-for-the-masses/

14.2.1 Sample installation on Debian Squeeze At this point we will give a short and simple sample installation howto for Debian Squeeze. Many other OS provide packages for QGIS Server, too. If you have to build it all from source, please refer to the URLs above. Apart from QGIS and QGIS Server you need a webserver, in our case apache2. You can install all packages with aptitude or apt-get install together with other necessary dependency packages. After installation you should test, if the webserver and QGIS Server works as expected. Make sure the apache server is running with /etc/init.d/apache2 start. Open a web browser and type URL: http://localhost. If apache is up, you should see the message ‘It works!’. Now we test the QGIS Server installation. The qgis_mapserv.fcgi is available at /usr/lib/cgi-bin/qgis_mapserv.fcgi and provides a standard wms that shows the state boundaries of Alaska. Add the WMS with the URL http://localhost/cgi-bin/qgis_mapserv.fcgi as described in Selecting WMS/WMTS Servers.

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Gambar 14.5: Standard WMS with USA boundaries included in the QGIS Server (KDE)

14.2.2 Creating a WMS/WFS from a QGIS project To provide a new QGIS Server WMS or WFS we have to create a QGIS project file with some data. Here we use the ‘alaska’ shapefile from the QGIS sample dataset. Define the colors and styles of the layers in QGIS and define the project CRS, if not already done.

Gambar 14.6: Definitions for a QGIS Server WMS/WFS project (KDE) Then go to the OWS Server menu of the Project → Project Properties dialog and give some information about the OWS in the fields under Service Capabilities. This will appear in the GetCapabilities response of the WMS or WFS. If you don’t check Service capabilities QGIS Server will use the information given in the wms_metadata.xml file located in the cgi-bin folder. In the WMS capabilities section you can define the extent advertised in the WMS GetCapabilities response by entering the minimum and maximum X and Y values in the fields under Advertised extent. Clicking Use Current Canvas Extent sets these values to the extent currently displayed in the QGIS map canvas. By checking CRS restrictions you can restrict in which coordinate reference systems (CRS) QGIS Server will offer to render maps.

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Use the button below to select those CRS from the Coordinate Reference System Selector, or click Used to add the CRS used in the QGIS project to the list. If you have print composers defined in your project they will be listed in the GetCapabilities response, and they can be used by the GetPrint request to create prints, using one of the print composer layouts as a template. This is a QGIS specific extension to the WMS 1.3.0 specification. If you want to exclude any print composer from Exclude composers and click the button below. Then select a print being published by the WMS, check composer from the Select print composer dialog in order to add it to the excluded composers list. If you want to exclude any layer or layer group from being published by the WMS, check

Exclude Layers

and click the button below. This opens the Select restricted layers and groups dialog which allows you to choose the layers and groups that you don’t want to be published. Use the shift or control key if you want to select multiple entries at once. Add WKT geometry to feature info response. This will include in the GetFeatureInfo If you wish you can check response the geometries of the features in a text format. If you want QGIS Server to advertise specific request URLs in the WMS GetCapabilities response, enter the corresponding URL in the Advertised URL field. Furthermore you can restrict the maximum size of the maps returned by the GetMap request by entering the maximum width and height into the respective fields under Maximums for GetMap request. In the WFS capabilities area you can select the layers that you want to provide as WFS, and specify if they will allow the update, insert and delete operations. If you enter a URL in the Advertised URL field of the WFS capabilities section, QGIS Server will advertise this specific URL in the WFS GetCapabilities response. Now save the session in a project file alaska.qgs. To provide the project as a WMS/WFS, we create a new folder /usr/lib/cgi-bin/project with admin privileges and add the project file alaska.qgs and a copy of the qgis_mapserv.fcgi file - that’s all. Now we test our project WMS and WFS, add the WMS and WFS as described in Loading WMS/WMTS Layers and WFS and WFS-T Client to QGIS and load the WMS. The URL is: http://localhost/cgi-bin/project/qgis_mapserv.fcgi

Fine tuning your OWS For vector layers, the Fields menu of the Layer → Properties dialog allows you to define for each attribute if it will be published or not. By default all the attributes are published by your WMS and WFS. If you want a specific attribute not to be published, uncheck the corresponding check box in the WMS or WFS column. You can overlay watermarks over the maps produced by your WMS by adding text annotations or SVG annotations to the project file. See sec_annotations for instructions on creating annotations. For annotations to be displayed as watermarks on the WMS output, the Fixed map position check box in the Annotation text dialog must be unchecked. This can be accessed by double clicking the annotation while one of the annotation tools is active. For SVG annotations you will either need to set the project to save absolute paths (in the General menu of the Project → Project Properties dialog) or to manually modify the path to the SVG image in a way that it represents a valid relative path. Extra parameters supported by the WMS GetMap request In the WMS GetMap request QGIS Server accepts a couple of extra parameters in addition to the standard parameters according to the OCG WMS 1.3.0 specification: • MAP parameter: Similar to MapServer, the MAP parameter can be used to specify the path to the QGIS project file. You can specify an absolute path or a path relative to the location of the server executable (qgis_mapserv.fcgi). If not specified, QGIS Server searches for .qgs files in the directory where the server executable is located. Example:

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http://localhost/cgi-bin/qgis_mapserv.fcgi?\ REQUEST=GetMap&MAP=/home/qgis/mymap.qgs&...

• DPI parameter: The DPI parameter can be used to specify the requested output resolution. Example: http://localhost/cgi-bin/qgis_mapserv.fcgi?REQUEST=GetMap&DPI=300&...

• OPACITIES parameter: Opacity can be set on layer or group level. Allowed values range from 0 (fully transparent) to 255 (fully opaque). Example: http://localhost/cgi-bin/qgis_mapserv.fcgi?\ REQUEST=GetMap&LAYERS=mylayer1,mylayer2&OPACITIES=125,200&...

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BAB 15

Pekerjaan dengan Data GPS

15.1 GPS Plugin 15.1.1 What is GPS? GPS, the Global Positioning System, is a satellite-based system that allows anyone with a GPS receiver to find their exact position anywhere in the world. It is used as an aid in navigation, for example in airplanes, in boats and by hikers. The GPS receiver uses the signals from the satellites to calculate its latitude, longitude and (sometimes) elevation. Most receivers also have the capability to store locations (known as waypoints), sequences of locations that make up a planned route and a tracklog or track of the receivers movement over time. Waypoints, routes and tracks are the three basic feature types in GPS data. QGIS displays waypoints in point layers while routes and tracks are displayed in linestring layers.

15.1.2 Loading GPS data from a file There are dozens of different file formats for storing GPS data. The format that QGIS uses is called GPX (GPS eXchange format), which is a standard interchange format that can contain any number of waypoints, routes and tracks in the same file. To load a GPX file you first need to load the plugin. Plugins →

Plugin Manager... opens the Plugin Manager

Dialog. Activate the GPS Tools checkbox. When this plugin is loaded two buttons with a small handheld GPS device will show up in the toolbar: •

Create new GPX Layer

•

GPS Tools

For working with GPS data we provide an example GPX file available in the QGIS sample dataset: qgis_sample_data/gps/national_monuments.gpx. See Section Contoh data for more information about the sample data. 1. Select Vector → GPS → GPS Tools or click the tab (see figure_GPS_1).

GPS Tools

icon in the toolbar and open the Load GPX file

2. Browse to the folder qgis_sample_data/gps/, select the GPX file national_monuments.gpx and click [Open]. Use the [Browse...] button to select the GPX file, then use the checkboxes to select the feature types you want to load from that GPX file. Each feature type will be loaded in a separate layer when you click [OK]. The file national_monuments.gpx only includes waypoints. Catatan: GPS units allow to store data in different coordinate systems. When downloading a GPX file (from your GPS unit or a web site) and then loading it in QGIS, be sure that the data stored in the

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Gambar 15.1: The GPS Tools dialog window GPX file uses WGS84 (latitude/longitude). QGIS expects this and it is the official GPX specification. See http://www.topografix.com/GPX/1/1/

15.1.3 GPSBabel Since QGIS uses GPX files you need a way to convert other GPS file formats to GPX. This can be done for many formats using the free program GPSBabel, which is available at http://www.gpsbabel.org. This program can also transfer GPS data between your computer and a GPS device. QGIS uses GPSBabel to do these things, so it is recommended that you install it. However, if you just want to load GPS data from GPX files you will not need it. Version 1.2.3 of GPSBabel is known to work with QGIS, but you should be able to use later versions without any problems.

15.1.4 Importing GPS data To import GPS data from a file that is not a GPX file, you use the tool Import other file in the GPS Tools dialog. Here you select the file that you want to import (and the file type), which feature type you want to import from it, where you want to store the converted GPX file and what the name of the new layer should be. Note that not all GPS data formats will support all three feature types, so for many formats you will only be able to choose between one or two types.

15.1.5 Downloading GPS data from a device QGIS can use GPSBabel to download data from a GPS device directly as new vector layers. For this we use the Download from GPS tab of the GPS Tools dialog (see Figure_GPS_2). Here, we select the type of GPS device, the port that it is connected to (or usb if your GPS supports this), the feature type that you want to download, the GPX file where the data should be stored, and the name of the new layer. The device type you select in the GPS device menu determines how GPSBabel tries to communicate with your GPS device. If none of the available types work with your GPS device you can create a new type (see section Defining new device types). The port may be a file name or some other name that your operating system uses as a reference to the physical port in your computer that the GPS device is connected to. It may also be simply usb, for usb enabled GPS units. •

On Linux this is something like /dev/ttyS0 or /dev/ttyS1

•

On Windows it is COM1 or COM2

When you click [OK] the data will be downloaded from the device and appear as a layer in QGIS.

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Gambar 15.2: The download tool

15.1.6 Uploading GPS data to a device You can also upload data directly from a vector layer in QGIS to a GPS device using the Upload to GPS tab of the GPS Tools dialog. To do this you simply select the layer that you want to upload (which must be a GPX layer), your GPS device type, and the port (or usb) that it is connected to. Just as with the download tool you can specify new device types if your device isn’t in the list. This tool is very useful in combination with the vector editing capabilities of QGIS. It allows you to load a map, create waypoints and routes, and then upload them and use them on your GPS device.

15.1.7 Defining new device types There are lots of different types of GPS devices. The QGIS developers can’t test all of them, so if you have one that does not work with any of the device types listed in the Download from GPS and Upload to GPS tools you can define your own device type for it. You do this by using the GPS device editor, which you start by clicking the [Edit devices] button in the download or the upload tabs. To define a new device you simply click the [New device] button, enter a name, a download command and an upload command for your device, and click the [Update device] button. The name will be listed in the device menus in the upload and download windows, and can be any string. The download command is the command that is used to download data from the device to a GPX file. This will probably be a GPSBabel command, but you can use any other command line program that can create a GPX file. QGIS will replace the keywords %type, %in, and %out when it runs the command. %type will be replaced by -w if you are downloading waypoints, -r if you are downloading routes and -t if you are downloading tracks. These are command line options that tell GPSBabel which feature type to download. %in will be replaced by the port name that you choose in the download window and %out will be replaced by the name you choose for the GPX file that the downloaded data should be stored in. So if you create a device type with the download command gpsbabel %type -i garmin -o gpx %in %out (this is actually the download command for the predefined device type ‘Garmin serial’) and then use it to download waypoints from port /dev/ttyS0 to the file output.gpx, QGIS will replace the keywords and run the command gpsbabel -w -i garmin -o gpx /dev/ttyS0 output.gpx. The upload command is the command that is used to upload data to the device. The same keywords are used, but %in is now replaced by the name of the GPX file for the layer that is being uploaded, and %out is replaced by the port name. You can learn more about GPSBabel and it’s available command line options at http://www.gpsbabel.org. Once you have created a new device type it will appear in the device lists for the download and upload tools.

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15.2 Live GPS tracking To activate Live GPS tracking in QGIS you need to select Settings → Panels new docked window on the left side of the canvas.

GPS information. You will get a

There are 4 possible screens in this GPS tracking window: •

GPS position coordinates and for manually entering Vertices and Features.

•

GPS signal strength of satellite connections.

•

GPS polar screen showing number and polar position of satellites.

•

GPS options screen (see figure_gps_options).

With a plugged in GPS receiver (has to be supported by your operating system) a simple click on [Connect] connects the GPS to QGIS. A second click (now on [Disconnect]) disconnects the GPS-receiver from your computer. For GNU/Linux gpsd support is integrated to support connection to most GPS receivers. Therefore you first have to configure gpsd properly to connect QGIS to it. Peringatan: If you want to record your position to the canvas you have to create a new vector layer first and switch it to editable status to be able to record your track.

15.2.1 Position and additional attributes If the GPS is receiving signals from satellites you will see your position in latitude, longitude and altitude together with additional attributes.

Gambar 15.3: GPS tracking position and additional attributes

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15.2.2 GPS signal strength Here you can see the signal strenght of the satellites you are receiving signals from.

Gambar 15.4: GPS tracking signal strength

15.2.3 GPS polar window If you want to know where in the sky all the connected satellites are, you have to switch to the polar screen. You can also see the ID numbers of the satellites you are receiving signals from.

Gambar 15.5: GPS tracking polar window

15.2.4 GPS options In case of connection problems you can switch between: •

Autodetect

•

Internal

•

Serial device

•

gpsd (selecting Host, Port and Device your GPS is connected to)

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Gambar 15.6: GPS tracking options window A click on [Connect] again initiates the connection to the GPS receiver. You can activate

Automatically save added features when you are in editing mode. Or you can can activate

Automatically add points to the map canvas with a certain width and color. Activating canvas.

Cursor you can use a slider

to shrink and grow the position cursor on the

Activating Map centering allows to decide in which way the canvas will be updated. This includes ‘always’, ‘when leaving’ if your recorded coordinates start either to move out of canvas or ‘never’ to keep map extent. Finally you can activate logged.

Log file and define a path and a file where log messages about the gps tracking a

If you want to set a feature manually you have to go back to point].

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Position

and click on [Add Point] or [Add track

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GRASS GIS Integration

The GRASS plugin provides access to GRASS GIS (see GRASS-PROJECT Literatur dan Referensi Web) databases and functionalities. This includes visualization of GRASS raster and vector layers, digitizing vector layers, editing vector attributes, creating new vector layers and analysing GRASS 2D and 3D data with more than 400 GRASS modules. In this Section we’ll introduce the plugin functionalities and give some examples on managing and working with GRASS data. Following main features are provided with the toolbar menu, when you start the GRASS plugin, as described in section sec_starting_grass : •

Open mapset

•

New mapset

•

Close mapset

•

Add GRASS vector layer

•

Add GRASS raster layer

•

Create new GRASS vector

•

Edit GRASS vector layer

•

Open GRASS tools

•

Display current GRASS region

•

Edit current GRASS region

16.1 Starting the GRASS plugin To use GRASS functionalities and/or visualize GRASS vector and raster layers in QGIS, you must select and load the GRASS plugin with the Plugin Manager. Therefore go to the menu Plugins →

Manage Plugins, select

GRASS and click [OK]. You can now start loading raster and vector layers from an existing GRASS LOCATION (see section sec_load_grassdata). Or you create a new GRASS LOCATION with QGIS (see section Creating a new GRASS LOCATION) and import some raster and vector data (see Section Importing data into a GRASS LOCATION) for further analysis with the GRASS Toolbox (see section The GRASS toolbox).

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16.2 Loading GRASS raster and vector layers With the GRASS plugin, you can load vector or raster layers using the appropriate button on the toolbar menu. As an example we use the QGIS alaska dataset (see Section Contoh data). It includes a small sample GRASS LOCATION with 3 vector layers and 1 raster elevation map. 1. Create a new folder grassdata, download the QGIS ‘Alaska’ dataset qgis_sample_data.zip from http://download.osgeo.org/qgis/data/ and unzip the file into grassdata. 2. Start QGIS. 3. If not already done in a previous QGIS session, load the GRASS plugin clicking on Plugins → Plugins and activate

Manage

GRASS. The GRASS toolbar appears in the QGIS main window.

4. In the GRASS toolbar, click the

Open mapset

icon to bring up the MAPSET wizard.

5. For Gisdbase browse and select or enter the path to the newly created folder grassdata. 6. You should now be able to select the LOCATION

alaska and the MAPSET

demo.

7. Click [OK]. Notice that some previously disabled tools in the GRASS toolbar are now enabled. Add GRASS raster layer , choose the map name gtopo30 and click [OK]. The elevation layer will 8. Click on be visualized. Add GRASS vector layer 9. Click on , choose the map name alaska and click [OK]. The Alaska boundary vector layer will be overlayed on top of the gtopo30 map. You can now adapt the layer properties as described in chapter The Vector Properties Dialog, e.g. change opacity, fill and outline color.

10. Also load the other two vector layers rivers and airports and adapt their properties. As you see, it is very simple to load GRASS raster and vector layers in QGIS. See following sections for editing GRASS data and creating a new LOCATION. More sample GRASS LOCATIONs are available at the GRASS website at http://grass.osgeo.org/download/sample-data/. Tip: GRASS Data Loading If you have problems loading data or QGIS terminates abnormally, check to make sure you have loaded the GRASS plugin properly as described in section sec_starting_grass.

16.3 GRASS LOCATION and MAPSET GRASS data are stored in a directory referred to as GISDBASE. This directory often called grassdata, must be created before you start working with the GRASS plugin in QGIS. Within this directory, the GRASS GIS data are organized by projects stored in subdirectories called LOCATION. Each LOCATION is defined by its coordinate system, map projection and geographical boundaries. Each LOCATION can have several MAPSETs (subdirectories of the LOCATION) that are used to subdivide the project into different topics, subregions, or as workspaces for individual team members (Neteler & Mitasova 2008 Literatur dan Referensi Web). In order to analyze vector and raster layers with GRASS modules, you must import them into a GRASS LOCATION (This is not strictly true - with the GRASS modules r.external and v.external you can create read-only links to external GDAL/OGR-supported data sets without importing them. But because this is not the usual way for beginners to work with GRASS, this functionality will not be described here.).

16.3.1 Creating a new GRASS LOCATION As an example here is how the sample GRASS LOCATION alaska, which is projected in Albers Equal Area projection with unit feet was created for the QGIS sample dataset. This sample GRASS LOCATION alaska

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Gambar 16.1: GRASS data in the alaska LOCATION will be used for all examples and exercises in the following GRASS GIS related chapters. It is useful to download and install the dataset on your computer Contoh data). 1. Start QGIS and make sure the GRASS plugin is loaded. 2. Visualize the alaska.shp shapefile (see Section vector_load_shapefile) from the QGIS alaska dataset Contoh data. 3. In the GRASS toolbar, click on the

New mapset

icon to bring up the MAPSET wizard.

4. Select an existing GRASS database (GISDBASE) folder grassdata or create one for the new LOCATION using a file manager on your computer. Then click [Next]. 5. We can use this wizard to create a new MAPSET within an existing LOCATION (see section Adding a new MAPSET) or to create a new LOCATION altogether. Select Create new location (see figure_grass_location_2). 6. Enter a name for the LOCATION - we used ‘alaska’ and click [Next]. 7. Define the projection by clicking on the radio button

Projection to enable the projection list.

8. We are using Albers Equal Area Alaska (feet) projection. Since we happen to know that it is represented by the EPSG ID 2964, we enter it in the search box. (Note: If you want to repeat this process for another LOCATION and projection and haven’t memorized the EPSG ID, click on the right-hand corner of the status bar (see Section Working with Projections)).

CRS Status

icon in the lower

9. In Filter insert 2964 to select the projection. 10. Click [Next]. 11. To define the default region, we have to enter the LOCATION bounds in north, south, east, and west direction. Here we simply click on the button [Set current QGIS extent], to apply the extend of the loaded layer alaska.shp as the GRASS default region extend. 12. Click [Next]. 13. We also need to define a MAPSET within our new LOCATION. You can name it whatever you like - we used ‘demo’ (when creating a new LOCATION). GRASS automatically creates a special MAPSET called

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PERMANENT designed to store the core data for the project, its default spatial extend and coordinate system definitions (Neteler & Mitasova 2008 Literatur dan Referensi Web). 14. Check out the summary to make sure it’s correct and click [Finish]. 15. The new LOCATION ‘alaska’ and two MAPSETs ‘demo’ and ‘PERMANENT’ are created. The currently opened working set is ‘demo’, as you defined. 16. Notice that some of the tools in the GRASS toolbar that were disabled are now enabled.

Gambar 16.2: Creating a new GRASS LOCATION or a new MAPSET in QGIS If that seemed like a lot of steps, it’s really not all that bad and a very quick way to create a LOCATION. The LOCATION ‘alaska‘ is now ready for data import (see section Importing data into a GRASS LOCATION). You can also use the already existing vector and raster data in the sample GRASS LOCATION ‘alaska’ included in the QGIS ‘Alaska’ dataset Contoh data and move on to Section The GRASS vector data model.

16.3.2 Adding a new MAPSET A user has only write access to a GRASS MAPSET he created. This means that besides access to his own MAPSET, each user can read maps in other user’s MAPSETs, but he can modify or remove only the maps in his own MAPSET. All MAPSETs include a WIND file that stores the current boundary coordinate values and the currently selected raster resolution (Neteler & Mitasova 2008 Literatur dan Referensi Web, see Section The GRASS region tool). 1. Start QGIS and make sure the GRASS plugin is loaded. 2. In the GRASS toolbar, click on the

New mapset

icon to bring up the MAPSET wizard.

3. Select the GRASS database (GISDBASE) folder grassdata with the LOCATION ‘alaska’, where we want to add a further MAPSET, called ‘test’. 4. Click [Next]. 5. We can use this wizard to create a new MAPSET within an existing LOCATION or to create a new LOCATION altogether. Click on the radio button Select location (see figure_grass_location_2) and click [Next]. 6. Enter the name text for the new MAPSET. Below in the wizard you see a list of existing MAPSETs and its owners. 7. Click [Next], check out the summary to make sure it’s all correct and click [Finish].

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16.4 Importing data into a GRASS LOCATION This Section gives an example how to import raster and vector data into the ‘alaska’ GRASS LOCATION provided by the QGIS ‘Alaska’ dataset. Therefore we use a landcover raster map landcover.img and a vector GML file lakes.gml from the QGIS ‘Alaska’ dataset Contoh data. 1. Start QGIS and make sure the GRASS plugin is loaded. 2. In the GRASS toolbar, click the

Open MAPSET

icon to bring up the MAPSET wizard.

3. Select as GRASS database the folder grassdata in the QGIS alaska dataset, as LOCATION ‘alaska’, as MAPSET ‘demo’ and click [OK]. 4. Now click the appears.

Open GRASS tools

icon. The GRASS Toolbox (see section The GRASS toolbox) dialog

5. To import the raster map landcover.img, click the module r.in.gdal in the Modules Tree tab. This GRASS module allows to import GDAL supported raster files into a GRASS LOCATION. The module dialog for r.in.gdal appears. 6. Browse to the folder raster in the QGIS ‘Alaska’ dataset and select the file landcover.img. 7. As raster output name define landcover_grass and click [Run]. In the Output tab you see the currently running GRASS command r.in.gdal -o input=/path/to/landcover.img output=landcover_grass. 8. When it says Succesfully finished click [View output]. The landcover_grass raster layer is now imported into GRASS and will be visualized in the QGIS canvas. 9. To import the vector GML file lakes.gml, click the module v.in.ogr in the Modules Tree tab. This GRASS module allows to import OGR supported vector files into a GRASS LOCATION. The module dialog for v.in.ogr appears. 10. Browse to the folder gml in the QGIS ‘Alaska’ dataset and select the file lakes.gml as OGR file. 11. As vector output name define lakes_grass and click [Run]. You don’t have to care about the other options in this example. In the Output tab you see the currently running GRASS command v.in.ogr -o dsn=/path/to/lakes.gml output=lakes\_grass. 12. When it says Succesfully finished click [View output]. The lakes_grass vector layer is now imported into GRASS and will be visualized in the QGIS canvas.

16.5 The GRASS vector data model It is important to understand the GRASS vector data model prior to digitizing. In general, GRASS uses a topological vector model. This means that areas are not represented as closed polygons, but by one or more boundaries. A boundary between two adjacent areas is digitized only once, and it is shared by both areas. Boundaries must be connected and closed without gaps. An area is identified (and labeled) by the centroid of the area. Besides boundaries and centroids, a vector map can also contain points and lines. All these geometry elements can be mixed in one vector and will be represented in different so called ‘layers’ inside one GRASS vector map. So in GRASS a layer is not a vector or raster map but a level inside a vector layer. This is important to distinguish carefully (Although it is possible to mix geometry elements, it is unusual and even in GRASS only used in special cases such as vector network analysis. Normally you should prefere to store different geometry elements in different layers.). It is possible to store several ‘layers’ in one vector dataset. For example, fields, forests and lakes can be stored in one vector. Adjacent forest and lake can share the same boundary, but they have separate attribute tables. It is also possible to attach attributes to boundaries. For example, the boundary between lake and forest is a road, so it can have a different attribute table. 16.4. Importing data into a GRASS LOCATION

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The ‘layer’ of the feature is defined by ‘layer’ inside GRASS. ‘Layer’ is the number which defines if there are more than one layer inside the dataset, e.g. if the geometry is forest or lake. For now, it can be only a number, in the future GRASS will also support names as fields in the user interface. Attributes can be stored inside the GRASS LOCATION as DBase or SQLITE3 or in external database tables, for example PostgreSQL, MySQL, Oracle, etc. Attributes in database tables are linked to geometry elements using a ‘category’ value. ‘Category’ (key, ID) is an integer attached to geometry primitives, and it is used as the link to one key column in the database table. Tip: Learning the GRASS Vector Model The best way to learn the GRASS vector model and its capabilities is to download one of the many GRASS tutorials where the vector model is described more deeply. See http://grass.osgeo.org/documentation/manuals/ for more information, books and tutorials in several languages.

16.6 Creating a new GRASS vector layer Create new GRASS vector To create a new GRASS vector layer with the GRASS plugin click the toolbar icon. Enter a name in the text box and you can start digitizing point, line or polygon geometries, following the procedure described in Section Digitizing and editing a GRASS vector layer.

In GRASS it is possible to organize all sort of geometry types (point, line and area) in one layer, because GRASS uses a topological vector model, so you don’t need to select the geometry type when creating a new GRASS vector. This is different from Shapefile creation with QGIS, because Shapefiles use the Simple Feature vector model (see Section Creating new Vector layers). Tip: Creating an attribute table for a new GRASS vector layer If you want to assign attributes to your digitized geometry features, make sure to create an attribute table with columns before you start digitizing (see figure_grass_digitizing_5).

16.7 Digitizing and editing a GRASS vector layer Edit GRASS vector layer The digitizing tools for GRASS vector layers are accessed using the icon on the toolbar. Make sure you have loaded a GRASS vector and it is the selected layer in the legend before clicking on the edit tool. Figure figure_grass_digitizing_2 shows the GRASS edit dialog that is displayed when you click on the edit tool. The tools and settings are discussed in the following sections.

Tip: Digitizing polygons in GRASS If you want to create a polygon in GRASS, you first digitize the boundary of the polygon, setting the mode to ‘No category’. Then you add a centroid (label point) into the closed boundary, setting the mode to ‘Next not used’. The reason is, that a topological vector model links attribute information of a polygon always to the centroid and not to the boundary. Toolbar In figure_grass_digitizing_1 you see the GRASS digitizing toolbar icons provided GRASS plugin. Table table_grass_digitizing_1 explains the available functionalities.

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Gambar 16.3: GRASS Digitizing Toolbar Icon

Tool

Purpose

New Point

Digitize new point

New Line

Digitize new line

New Boundary

Digitize new boundary (finish by selecting new tool)

New Centroid

Digitize new centroid (label existing area)

Move vertex

Move one vertex of existing line or boundary and identify new position

Add vertex

Add a new vertex to existing line

Delete vertex

Delete vertex from existing line (confirm selected vertex by another click)

Move element

Move selected boundary, line, point or centroid and click on new position

Split line

Split an existing line to 2 parts

Delete element

Delete existing boundary, line, point or centroid (confirm selected element by another click)

Edit attributes

Edit attributes of selected element (note that one element can represent more features, see above)

Close

Close session and save current status (rebuilds topology afterwards)

Table GRASS Digitizing 1: GRASS Digitizing Tools Category Tab The Category tab allows you to define the way in which the category values will be assigned to a new geometry element.

Gambar 16.4: GRASS Digitizing Category Tab • Mode: what category value shall be applied to new geometry elements. – Next not used - apply next not yet used category value to geometry element. – Manual entry - manually define the category value for the geometry element in the ‘Category’-entry field. – No category - Do not apply a category value to the geometry element. This is e.g. used for area boundaries, because the category values are connected via the centroid. 16.7. Digitizing and editing a GRASS vector layer

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• Category - A number (ID) is attached to each digitized geometry element. It is used to connect each geometry element with its attributes. • Field (layer) - Each geometry element can be connected with several attribute tables using different GRASS geometry layers. Default layer number is 1. Tip: Creating an additional GRASS ‘layer’ with QGIS If you would like to add more layers to your dataset, just add a new number in the ‘Field (layer)’ entry box and press return. In the Table tab you can create your new table connected to your new layer. Settings Tab The Settings tab allows you to set the snapping in screen pixels. The threshold defines at what distance new points or line ends are snapped to existing nodes. This helps to prevent gaps or dangles between boundaries. The default is set to 10 pixels.

Gambar 16.5: GRASS Digitizing Settings Tab Symbology Tab The Symbology tab allows you to view and set symbology and color settings for various geometry types and their topological status (e.g. closed / opened boundary).

Gambar 16.6: GRASS Digitizing Symbolog Tab Table Tab The Table tab provides information about the database table for a given ‘layer’. Here you can add new columns to an existing attribute table, or create a new database table for a new GRASS vector layer (see Section Creating a new GRASS vector layer). Tip: GRASS Edit Permissions You must be the owner of the GRASS MAPSET you want to edit. It is impossible to edit data layers in a MAPSET that is not yours, even if you have write permissions. 146

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Gambar 16.7: GRASS Digitizing Table Tab

16.8 The GRASS region tool The region definition (setting a spatial working window) in GRASS is important for working with raster layers. Vector analysis is by default not limited to any defined region definitions. But all newly-created rasters will have the spatial extension and resolution of the currently defined GRASS region, regardless of their original extension and resolution. The current GRASS region is stored in the $LOCATION/$MAPSET/WIND file, and it defines north, south, east and west bounds, number of columns and rows, horizontal and vertical spatial resolution. It is possible to switch on/off the visualization of the GRASS region in the QGIS canvas using the Display current GRASS region button. Edit current GRASS region With the icon you can open a dialog to change the current region and the symbology of the GRASS region rectangle in the QGIS canvas. Type in the new region bounds and resolution and click [OK]. It also allows to select a new region interactively with your mouse on the QGIS canvas. Therefore click with the left mouse button in the QGIS canvas, open a rectangle, close it using the left mouse button again and click [OK].

The GRASS module g.region provide a lot more parameters to define an appropriate region extend and resolution for your raster analysis. You can use these parameters with the GRASS Toolbox, described in Section The GRASS toolbox.

16.9 The GRASS toolbox Open GRASS Tools The box provides GRASS module functionalities to work with data inside a selected GRASS LOCATION and MAPSET. To use the GRASS toolbox you need to open a LOCATION and MAPSET where you have write-permission (usually granted, if you created the MAPSET). This is necessary, because new raster or vector layers created during analysis need to be written to the currently selected LOCATION and MAPSET.

The GRASS Shell inside the GRASS Toolbox provides access to almost all (more than 330) GRASS modules through a command line interface. To offer a more user friendly working environment, about 200 of the available GRASS modules and functionalities are also provided by graphical dialogs within the GRASS plugin Toolbox.

16.9.1 Working with GRASS modules The GRASS Shell inside the GRASS Toolbox provides access to almost all (more than 300) GRASS modules in a command line interface. To offer a more user friendly working environment, about 200 of the available GRASS modules and functionalities are also provided by graphical dialogs.

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Gambar 16.8: GRASS Toolbox and Module Tree A complete list of GRASS modules available in the graphical Toolbox in QGIS version 2.0 is available in the GRASS wiki (http://grass.osgeo.org/wiki/GRASS-QGIS_relevant_module_list). It is also possible to customize the GRASS Toolbox content. This procedure is described in Section Customizing the GRASS Toolbox. As shown in figure_grass_toolbox_1 , you can look for the appropriate GRASS module using the thematically grouped Modules Tree or the searchable Modules List tab. Clicking on a graphical module icon a new tab will be added to the toolbox dialog providing three new sub-tabs Options, Output and Manual. Options The Options tab provides a simplified module dialog where you can usually select a raster or vector layer visualized in the QGIS canvas and enter further module specific parameters to run the module.

Gambar 16.9: GRASS Toolbox Module Options The provided module parameters are often not complete to keep the dialog clear. If you want to use further module 148

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parameters and flags, you need to start the GRASS Shell and run the module in the command line. A new feature since QGIS 1.8 is the support for a show advanced options button below the simplified module dialog in the Options tab. At the moment it is only added to the module v.in.ascii as an example use, but will probably be part of more / all modules in the GRASS toolbox in future versions of QGIS. This allows to use the complete GRASS module options without the need to switch to the GRASS Shell. Output

Gambar 16.10: GRASS Toolbox Module Output The Output tab provides information about the output status of the module. When you click the [Run] button, the module switches to the Output tab and you see information about the analysis process. If all works well, you will finally see a Successfully finished message. Manual The Manual tab shows the HTML help page of the GRASS module. You can use it to check further module parameters and flags or to get a deeper knowledge about the purpose of the module. At the end of each module manual page you see further links to the Main Help index, the Thematic index and the Full index. These links provide the same information as if you use the module g.manual. Tip: Display results immediately If you want to display your calculation results immediately in your map canvas, you can use the ‘View Output’ button at the bottom of the module tab.

16.9.2 GRASS module examples The following examples will demonstrate the power of some of the GRASS modules. Creating contour lines The first example creates a vector contour map from an elevation raster (DEM). Assuming you have the Alaska LOCATION set up as explained in Section Importing data into a GRASS LOCATION.

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Gambar 16.11: GRASS Toolbox Module Manual

• First open the location by clicking the

Open mapset

button and choosing the Alaska location. Add GRASS raster layer

• Now load the gtopo30 elevation raster by clicking raster from the demo location. • Now open the Toolbox with the

Open GRASS tools

and selecting the gtopo30

button.

• In the list of tool categories double click Raster → Surface Management → Generate vector contour lines. • Now a single click on the tool r.contour will open the tool dialog as explained above Working with GRASS modules. The gtopo30 raster should appear as the Name of input raster. • Type into the Increment between Contour levels intervals of 100 meters.)

the value 100. (This will create contour lines at

• Type into the Name for output vector map the name ctour_100. • Click [Run] to start the process. Wait for several moments until the message Successfully finished appears in the output window. Then click [View Output] and [Close]. Since this is a large region, it will take a while to display. After it finishes rendering, you can open the layer properties window to change the line color so that the contours appear clearly over the elevation raster, as in The Vector Properties Dialog. Next zoom in to a small mountainous area in the center of Alaska. Zooming in close you will notice that the contours have sharp corners. GRASS offers the v.generalize tool to slightly alter vector maps while keeping their overall shape. The tool uses several different algorithms with different purposes. Some of the algorithms (i.e. Douglas Peuker and Vertex reduction) simplify the line by removing some of the vertices. The resulting vector will load faster. This process will be used when you have a highly detailed vector, but you are creating a very small scale map, so the detail is unnecessary. Tip: The simplify tool Note that the QGIS fTools plugin has a Simplify geometries → tool that works just like the GRASS v.generalize Douglas-Peuker algorithm.

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However, the purpose of this example is different. The contour lines created by r.contour have sharp angles that should be smoothed. Among the v.generalize algorithms there is Chaikens which does just that (also Hermite splines). Be aware that these algorithms can add additional vertices to the vector, causing it to load even more slowly. • Open the GRASS toolbox and double click the categories Vector → Develop map → Generalization, then click on the v.generalize module to open its options window. • Check that the ‘ctour_100’ vector appears as the Name of input vector. • From the list of algorithms choose Chaiken’s. Leave all other options at their default, and scroll down to the last row to enter in the field Name for output vector map ‘ctour_100_smooth’, and click [Run]. • The process takes several moments. Once Successfully finished appears in the output windows, click [View output] and then [close]. • You may change the color of the vector to display it clearly on the raster background and to contrast with the original contour lines. You will notice that the new contour lines have smoother corners than the original while staying faithful to the original overall shape.

Gambar 16.12: GRASS module v.generalize to smooth a vector map Tip: Other uses for r.contour The procedure described above can be used in other equivalent situations. If you have a raster map of precipitation data, for example, then the same method will be used to create a vector map of isohyetal (constant rainfall) lines.

Creating a Hillshade 3D effect Several methods are used to display elevation layers and give a 3D effect to maps. The use of contour lines as shown above is one popular method often chosen to produce topographic maps. Another way to display a 3D effect is by hillshading. The hillshade effect is created from a DEM (elevation) raster by first calculating the slope and aspect of each cell, then simulating the sun’s position in the sky and giving a reflectance value to each cell. Thus you get sun facing slopes lighted and the slopes facing away from the sun (in shadow) are darkened.

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• Begin this example by loading the gtopo30 elevation raster. Start the GRASS toolbox and under the Raster category double click to open Spatial analysis → Terrain analysis. • Then click r.shaded.relief to open the module. • Change the azimuth angle

270 to 315.

• Enter gtopo30_shade for the new hillshade raster, and click [Run]. • When the process completes, add the hillshade raster to the map. You should see it displayed in grayscale. • To view both the hill shading and the colors of the gtopo30 together shift the hillshade map below the gtopo30 map in the table of contents, then open the Properties window of gtopo30, switch to the transparency tab and set its transparency level to about 25%. You should now have the gtopo30 elevation with its colormap and transparency setting displayed above the grayscale hillshade map. In order to see the visual effects of the hillshading, turn off the gtopo30_shade map, then turn it back on. Using the GRASS shell The GRASS plugin in QGIS is designed for users who are new to GRASS, and not familiar with all the modules and options. As such, some modules in the toolbox do not show all the options available, and some modules do not appear at all. The GRASS shell (or console) gives the user access to those additional GRASS modules that do not appear in the toolbox tree, and also to some additional options to the modules that are in the toolbox with the simplest default parameters. This example demonstrates the use of an additional option in the r.shaded.relief module that was shown above.

Gambar 16.13: The GRASS shell, r.shaded.relief module The module r.shaded.relief can take a parameter zmult which multiplies the elevation values relative to the X-Y coordinate units so that the hillshade effect is even more pronounced. • Load the gtopo30 elevation raster as above, then start the GRASS toolbox and click on the GRASS shell. In the shell window type the command r.shaded.relief map=gtopo30 shade=gtopo30_shade2 azimuth=315 zmult=3 and press [Enter]. 152

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• After the process finishes shift to the Browse tab and double click on the new gtopo30_shade2 raster to display in QGIS. • As explained above, shift the shaded relief raster below the gtopo30 raster in the Table of Contents, then check transparency of the colored gtopo30 layer. You should see that the 3D effect stands out more strongly compared to the first shaded relief map.

Gambar 16.14: Displaying shaded relief created with the GRASS module r.shaded.relief

Raster statistics in a vector map The next example shows how a GRASS module can aggregate raster data and add columns of statistics for each polygon in a vector map. • Again using the Alaska data, refer to Importing data into a GRASS LOCATION to import the trees shapefile from the shapefiles directory into GRASS. • Now an intermediary step is required: centroids must be added to the imported trees map to make it a complete GRASS area vector (including both boundaries and centroids). • From the toolbox choose Vector → Manage features, and open the module v.centroids. • Enter as the output vector map ‘forest_areas’ and run the module. • Now load the forest_areas vector and display the types of forests - deciduous, evergreen, mixed - in different colors: In the layer Properties window, Symbology tab, choose from Legend type ‘Unique value’ and set the Classification field to ‘VEGDESC’. (Refer to the explanation of the symbology tab :ref:sec_symbology in the vector section). • Next reopen the GRASS toolbox and open Vector → Vector update by other maps. • Click on the v.rast.stats module. Enter gtopo30, and forest_areas. • Only one additional parameter is needed: Enter column prefix elev, and click [run]. This is a computationally heavy operation which will run for a long time (probably up to two hours). • Finally open the forest_areas attribute table, and verify that several new columns have been added including elev_min, elev_max, elev_mean etc. for each forest polygon.

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16.9.3 Working with the GRASS LOCATION browser Another useful feature inside the GRASS Toolbox is the GRASS LOCATION browser. In figure_grass_module_7 you can see the current working LOCATION with its MAPSETs. In the left browser windows you can browse through all MAPSETs inside the current LOCATION. The right browser window shows some meta information for selected raster or vector layers, e.g. resolution, bounding box, data source, connected attribute table for vector data and a command history.

Gambar 16.15: GRASS LOCATION browser The toolbar inside the Browser tab offers following tools to manage the selected LOCATION: •

Add selected map to canvas

•

Copy selected map

•

Rename selected map

•

Delete selected map

•

Set current region to selected map

•

Refresh browser window

The Rename selected map and Delete selected map only work with maps inside your currently selected MAPSET. All other tools also work with raster and vector layers in another MAPSET.

16.9.4 Customizing the GRASS Toolbox Nearly all GRASS modules can be added to the GRASS toolbox. A XML interface is provided to parse the pretty simple XML files which configures the modules appearance and parameters inside the toolbox. A sample XML file for generating the module v.buffer (v.buffer.qgm) looks like this:

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The parser reads this definition and creates a new tab inside the toolbox when you select the module. A more detailed description for adding new modules, changing the modules group, etc. can be found on the QGIS wiki at http://hub.qgis.org/projects/quantum-gis/wiki/Adding_New_Tools_to_the_GRASS_Toolbox

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BAB 17

QGIS kerangka pengolahan

17.1 Pengantar Bab ini memperkenalkan kerangka pengolahan QGIS, lingkungan geoprocessing yang dapat digunakan untuk memanggil algoritma asli dan pihak ketiga dari QGIS, membuat tugas analisis spasial Anda lebih produktif dan mudah untuk melakukannya. Pada bagian berikut kita akan meninjau bagaimana menggunakan unsur-unsur grafis dari kerangka kerja ini dan mengambil yang terbaik masing-masing dari mereka. Ada empat elemen dasar dalam kerangka GUI, yang digunakan untuk menjalankan algoritma untuk tujuan yang berbeda. Memilih salah satu alat atau lain akan tergantung pada jenis analisis yang akan dilakukan dan karakteristik tertentu dari masing-masing pengguna dan proyek. Semuanya (kecuali untuk antarmuka batch processing, yang disebut dari toolbox, seperti akan kita lihat) bisa diakses dari menu Pengolahan (Anda akan melihat lebih dari empat entri. Yang tersisa tidak digunakan untuk mengeksekusi algoritma dan akan dijelaskan nanti dalam bab ini). • Toolbox. Unsur utama dari GUI, digunakan untuk menjalankan algoritma tunggal atau menjalankan proses batch berdasarkan algoritma tersebut.

Gambar 17.1: Toolbox Pengolahan • Modeler grafis. Beberapa algoritma dapat dikombinasikan secara grafis dengan menggunakan modeler untuk mendefinisikan alur kerja, menciptakan satu proses yang melibatkan beberapa sub-proses • Sejarah pengelola. Semua tindakan dilakukan dengan menggunakan salah satu elemen tersebut disimpan dalam berkas sejarah dan dapat kemudian dengan mudah direproduksi menggunakan manajer sejarah • Antarmuka pengolahan batch. Antarmuka ini memungkinkan Anda untuk menjalankan proses batch dan mengotomatisasi eksekusi algoritma tunggal pada beberapa dataset.

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Gambar 17.2: Modeler Pengolahan

Gambar 17.3: Pengolahan Sejarah

Gambar 17.4: Antarmuka proses batch 158

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Sepanjang bagian berikut kita akan meninjau masing-masing elemen ini secara rinci.

17.2 The toolbox The Toolbox is the main element of the processing GUI, and the one that you are more likely to use in your daily work. It shows the list of all available algorithms grouped in different blocks, and is the access point to run them whether as a single process or as a batch process involving several executions of a same algorithm on different sets of inputs.

Gambar 17.5: Processing Toolbox The toolbox contains all the available algorithms, divided into predefined groups. All these groups are found under a single tree entry named Geoalgorithms. Additionally, two more entries are found, namely Models and Scripts. These include user-created algorithms, and allow you to define your own workflows and processing tasks. We will devote a full section to them a bit later. In the upper part of the toolbox you can find a text box. To reduce the number of algorithms shown in the toolbox and make it easier to find the one you need, you can enter any word or phrase on the text box. Notice that, as you type, the number of algorithms in the toolbox is reduced to just those which contain the text you have entered in their names. In the lower part you will find a box that allows you to switch between the simplified algorithm list (the one explained above), and the advanced list. If you change to the advanced mode, the toolbox will look like this: In the advanced view, each group represents a so-called ‘algorithm provider’, which is a set of algorithms coming from the same source, for instance, from a third-party application with geoprocessing capabilities. Some of this groups represent algorithms from one of such third-party applications (like SAGA, GRASS or R), while other contain algorithms directly coded as part of the processing plugin, not relying on any additional software. This view is recommended to those users that have a certain knowledge of the applications that are backing those algorithms, since they will be shown with their original names and groups. Also, some additional algorithms are available only in the advanced view, such as LiDAR tools or scripts based on the R statistical computing software, among others. Independent QGIS plugins that add new algorithms to the toolbox will only be shown in the advanced view. In particular, the simplified view contains algorithms from the following providers: • GRASS • SAGA • OTB • Native QGIS algorithms 17.2. The toolbox

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Gambar 17.6: Processing Toolbox (advanced mode) In the particular case of running QGIS under Windows, these algorithms are fully-functional in a fresh installation of QGIS and they can be run without requiring any additional installation. Also running them requires no prior knowledge of the external applications they use, making them more accesible for first-time users. If you want to use an algorithm not provided by the any of above providers, switch to the advanced mode by selecting the corresponding option at the bottom of the toolbox. To execute an algorithm, just double-click on its name in the toolbox.

17.2.1 The algorithm dialog Once you double-click on the name of the algorithm that you want to execute, a dialog similar to the next one is shown (in this case, the dialog corresponds to the SAGA ‘Convergence index’ algorithm).

Gambar 17.7: Parameters Dialog This dialog is used to set the input values that the algorithm needs to be executed. It shows a table where input values and configuration parameters are to be set. It, of course, has a different content depending on the requirements of the algorithm to be executed, and is created automatically based on those requirements. On the left side, the name of the parameter is shown. On the right side the value of the parameter can be set. 160

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Although the number and type of parameters depend on the characteristics of the algorithm, the structure is similar for all of them. The parameters found on the table can be of one of the following types. • A raster layer, to select from a list of all the ones available (currently opened) in QGIS. The selector contains as well a button on its right-hand side, to let you select filenames that represent layers currently not loaded in QGIS. • A vector layer, to select from a list of all the ones available in the QGIS. Layers not loaded in QGIS can be selected as well, as in the case of raster layers, but only if the algorithm does not require a table field selected from the attributes table of the layer. In that case, only opened layers can be selected, since they need to be open so as to retrieve the list of field names available. You will see a button by each vector layer selector, as shown in the figure below.

Gambar 17.8: Vector iterator button If the algorithm contains several of them, you will be able to toggle just one of them. If the button corresponding to a vector input is toggled, the algorithm will be executed iteratively on each one of its features instead of just once for the whole layer, producing as many outputs as times the algorithm is executed. This allows for automating the process when all features in a layer have to be processed separately. • A table, to select from a list of all the ones available in QGIS. Non-spatial tables are loaded into QGIS like vector layers, and in fact they are treated as such by the program. Currently, the list of available tables that you will see when executing an algorithm that needs one of them is restricted to tables coming from files in DBase (.dbf) or Comma-Separated Values (.csv) formats. • An option, to choose from a selection list of possible options. • A numerical value, to be introduced in a text box. You will find a button by its side. Clicking on it you will see a dialog that allows you to enter a mathematical expression, so you can use it as a handy calculator. Some useful variables related to data loaded into QGIS can be added to your expression, so you can select a value derived from any of this variables such as the cellsize of a layer or the northern most coordinate of another one.

Gambar 17.9: Number Selector • A range, with min and max values to be introduced in two text boxes. • A text string, to be introduced in a text box. 17.2. The toolbox

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• A field, to choose from the attributes table of a vector layer or a single table selected in another parameter. • A Coordinate Reference System. You can type the EPSG code directly in the text box, or select it from the CRS selection dialog that appear when you click on the button on the right-hand size • A extent, to be entered by four number representing its xmin, xmax, ymin, ymax limits. Clicking on the button on the right-hand side of the value selector, a pop-up menu will appear, giving you two option: to select the value from a layer or the current canvas extent, or to define it by dragging directly onto the map canvas.

Gambar 17.10: Extent selector If you select the first option, you will see a window like the next one.

Gambar 17.11: Extent List If you select the second one, the parameters window will hide itself, so you can click and drag onto the canvas. Once you have defined the selected rectangle, the dialog will reappear, containing the values in the extent text box.

Gambar 17.12: Extent Drag • A list of elements (whether raster layers, vector ones or tables), to select from the list of the ones available in QGIS. To make the selection, click on the small button on the left side of the corresponding row to see a dialog like the following one. • A small table to be edited by the user. These are used to define parameters like lookup tables or convolution kernels, among others. 162

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Gambar 17.13: Multiple Selection Click on the button on the right side to see the table and edit its values.

Gambar 17.14: Fixed Table Depending on the algorithm, the number of rows can be modified or not, using the buttons on the right side of the window. You will find a [Help] tab in the the parameters dialog. If a help file is available, it will be shown, giving you more information about the algorithms and detailed descriptions of what each parameter does. Unfortunately, most algorithms lack good documentation, but if you feel like contributing to the project, this would be a good place to start. A note on projections Algorithms run from the processing framework — and also most of the external applications whose algorithms are exposed through it — do not perform any reprojection on input layers and assumes that all of them are already in a common coordinate system and ready to be analized. Whenever you use more than one layer as input to an algorithm, whether vector or raster, it is up to you to make sure that they are all in the same coordinate system. Note that, due to QGIS‘s on-the-fly reprojecting capabilities, although two layers might seem to overlap and match, that might not be true if their original coordinates are used without reprojecting them onto a common coordinate system. That reprojection should be done manually and then use the resulting files as input to the algorithm. Also note that the reprojection process can be performed with the algorithms that are available in the processing framework itself. By default, the parameters dialog will show a description of the CRS of each layer along with its name, making it easy to select layers that share the same CRS to be used as input layers. If you do not want to see this additional information, you can disable this functionality in the processing config dialog, unchecking the Show CRS option.

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If you try to execute an algorithm using as input two or more layers with unmatching CRS’s, a warning dialog will be shown. You still can execute the algorithm, but be aware that in most cases that will produce wrong results, such as empty layers due to input layers not overlapping.

17.2.2 Data objects generated by algorithms Data objects generated by an algorithm can be of any of the following types: • A raster layer • A vector layer • A table • An HTML file (used for text and graphical outputs) They are all saved to disk, and the parameters table will contain a text box corresponding to each one of these outputs, where you can type the output channel to use for saving it. An output channel contains the information needed to save the resulting object somewhere. In the most usual case, you will save it to a file, but the architecture allows for any other way of storing it. For instance, a vector layer can be stored in a database or even uploaded to a remote server using a WFS-T service. Although solutions like these are not yet implemented, the processing framework is prepared to handle them, and we expect to add new kinds of output channels in a near feature. To select an output channel, just click on the button on the right side of the text box. That will open a save file dialog, where you can select the desired filepath. Supported file extensions are shown in the file format selector of the dialog, depending on the kind of output and the algorithm. The format of the output is defined by the filename extension. The supported formats depend on the ones supported by the algorithm itself. To select a format, just select the corresponding file extension (or add it if you are directly typing the filepath instead). If the extension of the filepath you entered does not match any of the supported ones, a default extension (usually .dbf‘ for tables, .tif for raster layers and .shp for vector ones) will be appended to the filepath and the file format corresponding to that extension will be used to save the layer or table. If you do not enter any filename, the result will be saved as a temporary file and in the corresponding default file format, and will be deleted once you exit QGIS (take care with that in case you save your project and it contains temporary layers). You can set a default folder for output data objects. Go to the configuration dialog (you can open it from the Processing menu), and in the General group you will find a parameter named Output folder. This output folder is used as the default path in case you type just a filename with no path (i.e. myfile.shp) when executing an algorithm. When running an algorithm that uses vector layer in iterative mode, the entered file path is used as the base path for all generated files, which are named using the base name and appending a number representing the index of the iteration. The file extension (and format) is used for all those generated files. Apart from raster layers and tables, algorithms also generates graphics and texts as HTML files. These results are shown at the end of the algorithm execution in a new dialog. This dialog will keep the results produced by any algorithm during the current session, and can be shown at any time by selecting the Processing → Results viewer from QGIS main menu. Some external applications might have files (with no particular extension restrictions) as output, but they do not belong to any of the categories above. Those output files will not be processed by QGIS (opened or included into the current QGIS project), since most of the times correspond to file formats or elements not supported by QGIS. This is, for instance, the case with LAS files used for LiDAR data. The files get created, but you won’t see anything new in your QGIS working session. For all the other types of outputs, you will find a check box that you can use to tell the algorithm whether to load the file once it is generated by the algorithm or not. By default, all files are opened. Optional outputs are not supported, so all outputs are created, but you can uncheck the corresponding check box if you are not interested in a given output, which virtually makes it behave like an optional output (although the

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layer is created anyway, but if you leave the text box empty, it will be saved to a temporary file and deleted once you exit QGIS)

17.2.3 Configuring the processing framework As it has been mentioned, the configuration menu gives access to a new dialog where you can configure how algorithms work. Configuration parameters are structured in separate blocks that you can select on the left-hand side of the dialog. Along with the aforementioned Output folder entry, the General block contains parameters for setting the default rendering style for output layers (that is, layers generated by using algorithms from any of the framework GUI components). Just create the style you want using QGIS, save it to a file, and then enter the path to that file in the settings so the algorithms can use it. Whenever a layer is loaded by SEXTANTE and added to the QGIS canvas, it will be rendered with that style. Rendering styles can be configured individually for each algorithm and each one of its outputs. Just right-click on the name of the algorithm in the toolbox and select Edit rendering styles. You will see a dialog like the one shown next.

Gambar 17.15: Rendering Styles Select the style file (.qml) that you want for each output and press [OK]. Other configuration parameters in the General group are the following ones: • Use filename as layer name. The name of each resulting layer created by an algorithm is defined by the algorithm itself. In some cases, a fixed name might be used, that meaning that the same name will be used, no matter which input layer is used. In other cases, the name might depend on the name of the input layer or some of the parameters used to run the algorithm. If this checkbox is checked, the name will be taken from the output filename instead. Notice, that, if the output is saved to a temporary file, the filename of this temporary file is usually long and meaningless one intended to avoid collision with other already existing filenames. • Use only selected features. If this option is selected, whenever a vector layer is used as input for an algorithm, only its selected features will be used. If the layer has no selected features, all of them will be used. • Pre-execution script file and Post-execution script file. This parameters refer to scripts written using the processing scripting functionality, and are explained in the section covering scripting and the console. Apart from the General block in the settings dialog, you will also find one for each algorithm provider. They contain an Activate item that you can use to make algorithms appear or not in the toolbox. Also, some algorithm providers have their own configuration items, that we will explain later when covering particular algorithm providers.

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17.3 The graphical modeler The graphical modeler allows to create complex models using a simple and easy-to-use interface. When working with a GIS, most analysis operations are not isolated, but part of a chain of operations instead. Using the graphical modeler, that chain of processes can be wrapped into a single process, so it is easier and more convenient to execute than a single process later on a different set on inputs. No matter how many steps and different algorithms it involves, a model is executed as a single algorithm, thus saving time and effort, specially for larger models. The modeler can be opened from the processing menu. The modeler has a working canvas where the structure of the model and the workflow it represents are shown. On the left part of the window, a panel with two tabs can be used to add new elements to the model.

Gambar 17.16: Modeler Creating a model involves two steps: 1. Definition of necessary inputs. These inputs will be added to the parameters window, so the user can set their values when executing the model. The model itself is an algorithm, so the parameters window is generated automatically as it happens with all the algorithms available in the processign framework. 2. Definition of the workflow. Using the input data of the model, the workflow is defined adding algorithms and selecting how they use those inputs or the outputs generated by other algorithms already in the model

17.3.1 Definition of inputs The first step to create a model is to define the inputs it needs. The following elements are found in the Inputs tab on the left side of the modeler window: • Raster layer • Vector layer • String • Table field • Table • Extent • Number • Boolean • File 166

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Double-clicking on any of them, a dialog is shown to define its characteristics. Depending on the parameter itself, the dialog will contain just one basic element (the description, which is what the user will see when executing the model) or more of them. For instance, when adding a numerical value, as it can be seen in the next figure, apart from the description of the parameter you have to set a default value and a range of valid values.

Gambar 17.17: Model Parameters For each added input, a new element is added to the modeler canvas.

Gambar 17.18: Model Parameters

17.3.2 Definition of the workflow Once the inputs have been defined, it is time to define the algorithms to apply on them. Algorithms can be found in the Algorithms tab, grouped much in the same way as they are in the toolbox.

Gambar 17.19: Model Parameters The appearance of the toolbox has two modes here as well: simplified and advanced. However, there is no element 17.3. The graphical modeler

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to switch between views in the modeler, and you have to do it in the toolbox. The mode that is selected in the toolbox is the one that will be used for the list of algorithms in the modeler. To add an algorithm to a model, double-click on its name. An execution dialog will appear, with a content similar to the one found in the execution panel that is shown when executing the algorithm from the toolbox. The one shown next correspond to the SAGA ‘Convergence index’ algorithm, the same one we saw in the section dedicated to the toolbox.

Gambar 17.20: Model Parameters As you can see, some differences exist. Instead of the file output box that was used to set the filepath for output layers and tables, a simple text box is. If the layer generated by the algorithm is just a temporary result that will be used as the input of another algorithm and should not be kept as a final result, just do not edit that text box. Typing anything on it means that the result is a final one, and the text that you supply will be the description for the output, which will be the one the user will see when executing the model. Selecting the value of each parameter is also a bit different, since there are important differences between the context of the modeler and the toolbox one. Let’s see how to introduce the values for each type of parameter. • Layers (raster and vector) and tables. They are selected from a list, but in this case the possible values are not the layers or tables currently loaded in QGIS, but the list of model inputs of the corresponding type, or other layers or tables generated by algorithms already added to the model. • Numerical values. Literal values can be introduced directly on the text box. But this text box is also a list that can be used to select any of the numerical value inputs of the model. In this case, the parameter will take the value introduced by the user when executing the model. • String. Like in the case of numerical values, literal strings can be typed, or an input string can be selected. • Table field. The fields of the parent table or layer cannot be known at design-time, since they depend of the selection of the user each time the model is executed. To set the value for this parameter, type the name of a field directly in the text box, or use the list to select a table field input already added to the model. The validity of the selected field will be checked at run-time. In all cases, you will find an additional parameter named Parent algorithms that is not available when calling the algorithm from the toolbox. This parameter allows you to define the order in which algorithms are executed, by explicitly defining one algorithm as a parent of the current one, which will force it to be executed before it. When you use the output of a previous algorithm as the input of your algorithm, that implicitly sets the former as parent of the current one (and places the corresponding arrow in the modeler canvas). However, in some cases an algorithm might depend on another one even if it does not use any output object from it (for instance, and algorithm that executes an SQL sentence on a PostGIS database and another one which imports a layer into that

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same database) In that case, just select it in the Parent algorithms parameter and they will be executed in the correct order. Once all the parameter have been assigned valid values, click on [OK] and the algorithm will be added to the canvas. It will be linked to all the other elements in the canvas, whether algorithms or inputs, which provide objects that are used as inputs for that algorithm.

Gambar 17.21: Model Parameters Elements can be dragged to a different position within the canvas, to change the way the module structure is displayed and make it more clear and intuitive. Links between elements are update automatically. You can run your algorithm anytime clicking on the [Run] button. However, in order to use it from the toolbox, it has to be saved and the modeler dialog closed, to allow the toolbox to refresh its contents.

17.3.3 Saving and loading models Use the [Save] button to save the current model and the [Open] one to open any model previously saved. Model are saved with the .model extension. If the model has been previously saved from the modeler window, you will not be prompted for a filename, since there is already a file associated with that model, and it will be used. Before saving a model, you have to enter a name and a group for it, using the text boxes in the upper part of the window. Models saved on the models folder (the default folder when you are prompted for a filename to save the model) will appear in the toolbox in the corresponding branch. When the toolbox is invoked, it searches the models folder for files with .model extension and loads the models they contain. Since a model is itself an algorithm, it can be added to the toolbox just like any other algorithm. The models folder can be set from the processing configuration dialog, under the Modeler group. Models loaded from the models folder appear not only in the toolbox, but also in the algorithms tree in the Algorithms tab of the modeler window. That means that you can incorporate a model as a part of a bigger model, just as you add any other algorithm. In some cases, a model might not be loaded because not all the algorithms included in its workflow are available. If you have used a given algorithm as part of your model, it should be available (that is, it should appear on the toolbox) in order to load that model. Deactivating an algorithm provider in the processing configuration window renders all the algorithms in that provider unusable by the modeler, which might cause problems when loading models. Keep that in mind when you have trouble loading or executing models.

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17.3.4 Editing a model You can edit the model you are currently creating, redefining the workflow and the relationships between the algorithms and inputs that define the model itself. If you right-click on an algorithm in the canvas representing the model, you will see a context menu like the one shown next:

Gambar 17.22: Modeler Right Click Selecting the Remove option will cause the selected algorithm to be removed. An algorithm can be removed only if there are no other algorithms depending on it. That is, if no output from the algorithm is used in a different one as input. If you try to remove an algorithm that has others depending on it, a warning message like the one you can see below will be shown:

Gambar 17.23: Cannot Delete Algorithm Selecting the Edit option or simply double-clicking on the algorithm icon will show the parameters dialog of the algorithm, so you can change the inputs and parameter values. Not all input elements available in the model will appear in this case as available inputs. Layers or values generated at a more advanced step in the workflow defined by the model will not be available if they cause circular dependencies. Select the new values and then click on the [OK] button as usual. The connections between the model elements will change accordingly in the modeler canvas.

17.3.5 Activating and deactivating algorithms Algorithms can be deactivated in the modeler, so they will not be executed once the model is run. This can be used to test just a given part of the model, or when you do not need all the outputs it generates. To deactivate an algorithm, right-click on its icon in the model canvas and select the Deactivate option. You will see that the algorithm is represented now with a red label under its name indicating that is not active.

Gambar 17.24: Deactivate

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All algorithms depending (directly or undirectly) on that algorithm will also appear as inactive, since they cannot be executed now. To activate an algorithm, just right–click on its icon and select the Activate option.

17.3.6 Editing model help files and meta-information You can document your models from the modeler itself. Just click on the [Edit model help] button and a dialog like the one shown next will appear.

Gambar 17.25: Help Edition On the right-hand side you will see a simple HTML page, created using the description of the input parameters and outputs of the algorithm, along with some additional items like a general description of the model or its author. The first time you open the help editor all those descriptions are empty, but you can edit them using the elements on the left-hand side of the dialog. Select an element on the upper part and the write its description in the text box below. Model help is saved in a file in the same folder as the model itself. You do not have to worry about saving it, since it is done automatically.

17.3.7 About available algorithms You might notice that some algorithms that can be be executed from the toolbox do not appear in the list of available ones when you are designing a model. To be included in a model, and algorithm must have a correct semantic, so as to be properly linked to other in the workflow. If an algorithm does not have such well-defined semantic (for instance, if the number of output layers cannot be know in advance), then it is not possible to use it within a model, and thus does not appear in the list of them that you can find in the modeler dialog. Additionally, you will see some algorithms in the modeler that are not found in the toolbox. This algorithms are meant to be used exclusively as part of a model, and they are of no interest in a different context. The ‘Calculator’ algorithm is an example of that. It is just a simple arithmetic calculator that you can use to modify numerical values (entered by the user or generated by some other algorithm). This tools is really useful within a model, but outside of that context, it doesn’t make too much sense.

17.3.8 Saving models as Python code Given a model, it is possible to automatically create Python code that performs the same task as the model itself. This code is used to create a console script (we will explain them later in this manual) and you can modify that script to incorporate actions and methods not available in the graphical modeler, such as loops or conditional sentences.

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This feature is also a very practical way of learning how to use processign algorithms from the console and how to create new algorithms using Python code, so you can use it as a learning tool when you start creating your own scripts. Save your model in the models folder and go to the toolbox, where it should appear now, ready to be run. Right click on the model name and select Save as Python script in the context menu that will pop-up. A dialog will prompt you to introduce the file where you want to save the script.

17.4 The batch processing interface 17.4.1 Introduction All algorithms (including models) can be executed as a batch process. That is, they can be executed using not a single set of inputs, but several of them, executing the algorithm as many times as needed. This is useful when processing large amounts of data, since it is not necessary to launch the algorithm many times from the toolbox. To execute an algorithm as a batch process, right-click on its name in the toolbox and select the Execute as batch process option in the pop-up menu that will appear.

Gambar 17.26: Batch Processing Right Click

17.4.2 The parameters table Executing a batch process is similar to performing a single execution of an algorithm. Parameter values have to be defined, but in this case we need not just a single value for each parameter, but a set of them instead, one for each time the algorithm has to be executed. Values are introduced using a table like the one shown next.

Gambar 17.27: Batch Processing Each line of this table represents a single execution of the algorithm, and each cell contains the value of one of the parameters. It is similar to the parameters dialog that you see when executing an algorithm from the toolbox, but with a different arrangement. By default, the table contains just two rows. You can add or remove rows using the buttons on the lower part of the window. 172

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Once the size of the table has been set, it has to be filled with the desired values.

17.4.3 Filling the parameters table For most parameters, setting its value is trivial. Just type the value or select it from the list of available options, depending on the parameter type. The main differences are found for parameters representing layers or tables, and for output filepaths. Regarding input layers and tables, when an algorithm is executed as part of a batch process those input data objects are taken directly from files, and not from the set of them already opened in QGIS. For this reason, any algorithm can be executed as a batch process even if no data objects at all are opened and the algorithm cannot be run from the toolbox. button Filenames for input data objects are introduced directly typing or, more conveniently, clicking on the on the right hand of the cell, which shows a typical file chooser dialog. Multiple files can be selected at once. If the input parameter represents a single data object and several files are selected, each one of them will be put in a separate row, adding new ones if needed. If it represents a multiple input, all the selected files will be added to a single cell, separated by semicolons (;). Output data objects are always saved to a file and, unlike when executing an algorithm from the toolbox, saving to a temporary one is not permitted. You can type the name directly or use the file chooser dialog that appears when clicking on the accompanying button. Once you select the file, a new dialog is shown to allow for autocompletion of other cells in the same column (same parameter).

Gambar 17.28: Batch Processing Save If the default value (‘Do not autocomplete’) is selected, it will just put the selected filename in the selected cell from the parameters table. If any of the other options is selected, all the cells below the selected one will be automatically filled based on a defined criteria. This way, it is much easier to fill the table, and the batch process can be defined with less effort. Automatic filling can be done simply adding correlative numbers to the selected filepath, or appending the value of another field at the same row. This is particularly useful for naming output data object according to input ones.

Gambar 17.29: Batch Processing File Path

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17.4.4 Executing the batch process To execute the batch process once you have introduced all the necessary values, just click on [OK]. Progress of the global batch task will be shown in the progress bar in the lower part of the dialog.

17.5 Using processing algorithms from the console The console allows advanced users to increase their productivity and perform complex operations that cannot be performed using any of the other GUI elements of the processing framework GUI. Models involving several algorithms can be defined using the command-line interface, and additional operations such as loops and conditional sentences can be added to create more flexible and powerful workflows. There is not a proccesing console in QGIS, but all processing commands are available instead from the QGIS built-in Python console. That means that you can incorporate those command to your console work and connect processing algorithms to all the other features (including methods from the QGIS API) available from there. The code that you can execute from the Python console, even if it does not call any specific processing method, can be converted into a new algorithm that you can later call from the toolbox, the graphical modeler or any other component, just like you do with any other algorithm. In fact, some algorithms that you can find in the toolbox are simple scripts. In this chapter we will see how to use processing algorithms from the QGIS Python console, and also how to write your own algorithms using Python.

17.5.1 Calling algorithms from the Python console The first thing you have to do is to import the processing functions with the following line: >>> import processing

Now, there is basically just one (interesting) thing you can do with that from the console: to execute an algorithm. That is done using the runalg() method, which takes the name of the algorithm to execute as its first parameter, and then a variable number of additional parameter depending on the requirements of the algorithm. So the first thing you need to know is the name of the algorithm to execute. That is not the name you see in the toolbox, but rather a unique command–line name. To find the right name for your algorithm, you can use the algslist() method. Type the following line in you console: >>> processing.alglist()

You will see something like this. Accumulated Cost (Anisotropic)---------------->saga:accumulatedcost(anisotropic) Accumulated Cost (Isotropic)------------------>saga:accumulatedcost(isotropic) Add Coordinates to points--------------------->saga:addcoordinatestopoints Add Grid Values to Points--------------------->saga:addgridvaluestopoints Add Grid Values to Shapes--------------------->saga:addgridvaluestoshapes Add Polygon Attributes to Points-------------->saga:addpolygonattributestopoints Aggregate------------------------------------->saga:aggregate Aggregate Point Observations------------------>saga:aggregatepointobservations Aggregation Index----------------------------->saga:aggregationindex Analytical Hierarchy Process------------------>saga:analyticalhierarchyprocess Analytical Hillshading------------------------>saga:analyticalhillshading Average With Mask 1--------------------------->saga:averagewithmask1 Average With Mask 2--------------------------->saga:averagewithmask2 Average With Thereshold 1--------------------->saga:averagewiththereshold1 Average With Thereshold 2--------------------->saga:averagewiththereshold2 Average With Thereshold 3--------------------->saga:averagewiththereshold3 B-Spline Approximation------------------------>saga:b-splineapproximation ...

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That’s a list of all the available algorithms, alphabetically ordered, along with their corresponding command-line names. You can use a string as a parameter for this method. Instead of returning the full list of algorithm, it will only display those that include that string. If, for instance, you are looking for an algorithm to calculate slope from a DEM, type alglist("slope") to get the following result: DTM Filter (slope-based)---------------------->saga:dtmfilter(slope-based) Downslope Distance Gradient------------------->saga:downslopedistancegradient Relative Heights and Slope Positions---------->saga:relativeheightsandslopepositions Slope Length---------------------------------->saga:slopelength Slope, Aspect, Curvature---------------------->saga:slopeaspectcurvature Upslope Area---------------------------------->saga:upslopearea Vegetation Index[slope based]----------------->saga:vegetationindex[slopebased]

This result might change depending on the algorithms you have available. It is easier now to find the algorithm you are looking for and its command-line name, in this case saga:slopeaspectcurvature. Once you know the command-line name of the algorithm, the next thing to do is to know the right syntax to execute it. That means knowing which parameters are needed and the order in which they have to be passed when calling the runalg() method. There is a method to describe an algorithm in detail, which can be used to get a list of the parameters that an algorithms require and the outputs that it will generate. To do it, you can use the alghelp(name_of_the_algorithm) method. Use the command-line name of the algorithm, not the full descriptive name. Calling the method with saga:slopeaspectcurvature as parameter, you get the following description. >>> processing.alghelp("saga:slopeaspectcurvature") ALGORITHM: Slope, Aspect, Curvature ELEVATION METHOD SLOPE ASPECT CURV HCURV VCURV

Now you have everything you need to run any algorithm. As we have already mentioned, there is only one single command to execute algorithms: runalg(). Its syntax is as follows: >>> processing.runalg(name_of_the_algorithm, param1, param2, ..., paramN, Output1, Output2, ..., OutputN)

The list of parameters and outputs to add depends on the algorithm you want to run, and is exactly the list that the alghelp() method gives you, in the same order as shown. Depending on the type of parameter, values are introduced differently. The next one is a quick review of how to introduce values for each type of input parameter: • Raster Layer, Vector Layer or Table. Simply use a string with the name that identifies the data object to use (the name it has in the QGIS Table of Contents) or a filename (if the corresponding layer is not opened, it will be opened, but not added to the map canvas). If you have an instance of a QGIS object representing the layer, you can also pass it as parameter. If the input is optional and you do not want to use any data object, use None. • Selection. If an algorithm has a selection parameter, the value of that parameter should be entered using an integer value. To know the available options, you can use the algoptions() command, as shown in the following example: >>> processing.algoptions("saga:slopeaspectcurvature") METHOD(Method) 0 - [0] Maximum Slope (Travis et al. 1975) 1 - [1] Maximum Triangle Slope (Tarboton 1997)

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2 3 4 5 6

-

[2] [3] [4] [5] [6]

Least Squares Fitted Fit 2.Degree Polynom Fit 2.Degree Polynom Fit 2.Degree Polynom Fit 3.Degree Polynom

Plane (Horn 1981, Costa-Cabral & Burgess 1996) (Bauer, Rohdenburg, Bork 1985) (Heerdegen & Beran 1982) (Zevenbergen & Thorne 1987) (Haralick 1983)

In this case, the algorithm has one of such such parameters, with 7 options. Notice that ordering is zerobased. • Multiple input. The value is a string with input descriptors separated by semicolons (;). As in the case of single layers or tables, each input descriptor can be the data object name, or its filepath. • Table Field from XXX. Use a string with the name of the field to use. This parameter is case-sensitive. • Fixed Table. Type the list of all table values separated by commas (,) and enclosed between quotes ("). Values start on the upper row and go from left to right. You can also use a 2D array of values representing the table. • CRS. Enter the EPSG code number of the desired CRS. • Extent. You must use a string with xmin, xmax, ymin and ymax values separated by commas (,). Boolean, file, string and numerical parameters do not need any additional explanations. Input parameters such as strings booleans or numerical values have default values. To use them, use None in the corresponding parameter entry. For output data objects, type the filepath to be used to save it, just as it is done from the toolbox. If you want to save the result to a temporary file, use None. The extension of the file determines the file format. If you enter a file extension not included in the ones supported by the algorithm, the default file format for that output type will be used, and its corresponding extension appended to the given filepath. Unlike when an algorithm is executed from the toolbox, outputs are not added to the map canvas if you execute that same algorithm from the Python Console. If you want to add an output to it, you have to do it yourself after running the algorithm. To do so, you can use QGIS API commands, or, even easier, use one of the handy methods provided for such task. The runalg method returns a dictionary with the output names (the ones shown in the algorithm description) as keys and the filepaths of those outputs as values. You can load those layers by passing its filepath to the load() method.

17.5.2 Additional functions for handling data Apart from the functions used to call algorithms, importing the processing package will also import some additional functions that make it easier to work with data, particularly vector data. They are just convenience functions that wrap some functionality from the QGIS API, usually with a less complex syntax. These functions should be used when developing new algorithms, as they make it easier to operate with input data. Below is a list of some of this commands. More information can be found in the classes under the processing/tools package, and aso in the example scripts provided with QGIS. • getobject(obj): Returns a QGIS object (a layer or table) from the passed object, which can be a filename or the name of the object in the QGIS Table of Contents. • values(layer, fields): Returns the values in the attributes table of a vector layer, for the passed fields. Fields can be passed as field names or as zero-based field indices. Returns a dict of lists, with the passed field identifiers as keys. It considers the existing selection • getfeatures(layer): Returns an iterator over the features of a vector layer, considering the existing selection. • uniquelabels(layer, field): Returns a list of unique values for a given attribute. Attribute can be passed as a field name or a zero-based field index. It considers the existing selection

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17.5.3 Creating scripts and running them from the toolbox You can create your own algorithms by writing the corresponding Python code and adding a few extra lines to supply additional information needed to define the semantics of the algorithm. You can find a Create new script menu under the Tools group in the Script algorithms block of the toolbox. Double-click on it to open the script edition dialog. That’s where you should type your code. Saving the script from there in the scripts folder (the default one when you open the save file dialog), with .py extension, will automatically create the corresponding algorithm. The name of the algorithm (the one you will see in the toolbox) is created from the filename, removing its extension and replacing low hyphens with blank spaces. Let’s have the following code, which calculates the Topographic Wetness Index (TWI) directly from a DEM ##dem=raster ##twi=output ret_slope = processing.runalg("saga:slopeaspectcurvature", dem, 0, None, None, None, None, None) ret_area = processing.runalg("saga:catchmentarea(mass-fluxmethod)", dem, 0, False, False, False, False, None, None, None, None, None) processing.runalg("saga:topographicwetnessindex(twi), ret_slope[’SLOPE’], ret_area[’AREA’], None, 1, 0, twi)

As you can see, it involves 3 algorithms, all of them coming from SAGA. The last one of them calculates the TWI, but it needs a slope layer and a flow accumulation layer. We do not have these ones, but since we have the DEM, we can calculate them calling the corresponding SAGA algorithms. The part of the code where this processing takes place is not difficult to understand if you have read the previous sections in this chapter. The first lines, however, need some additional explanation. They provide the information that is needed to turn your code into an algorithm that can be run from any of the GUI components, like the toolbox or the graphical modeler. These lines start with a double Python comment symbol (##) and have the following structure [parameter_name]=[parameter_type] [optional_values]

Here is a list of all the parameter types that are supported in processign scripts, their syntax and some examples. • raster. A raster layer • vector. A vector layer • table. A table • number. A numerical value. A default value must be provided. For instance, depth=number 2.4 • string. A text string. As in the case of numerical values, a default value must be added. For instance, name=string Victor • boolean. A boolean value. Add True or False after it to set the default value. For example, verbose=boolean True • multiple raster. A set of input raster layers. • multiple vector. A set of input vector layers. • field. A field in the attributes table of a vector layer. The name of the layer has to be added after the field tag. For instance, if you have declared a vector input with mylayer=vector, you could use myfield=field mylayer to add a field from that layer as parameter. • folder. A folder • file. A filename The parameter name is the name that will be shown to the user when executing the algorithm, and also the variable name to use in the script code. The value entered by the user for that parameter will be assigned to a variable with that name.

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When showing the name of the parameter to the user, the name will be edited it to improve its appearance, replacing low hyphens with spaces. So, for instance, if you want the user to see a parameter named A numerical value, you can use the variable name A_numerical_value. Layers and tables values are strings containing the filepath of the corresponding object. To turn them into a QGIS object, you can use the processing.getObjectFromUri() function. Multiple inputs also have a string value, which contains the filepaths to all selected object, separated by semicolons (;). Outputs are defined in a similar manner, using the following tags: • output raster • output vector • output table • output html • output file • output number • output string The value assigned to the output variables is always a string with a filepath. It will correspond to a temporary filepath in case the user has not entered any output filename. When you declare an output, the algorithm will try to add it to QGIS once it is finished. That is the reason why, although the runalg() method does not load the layers it produces, the final TWI layer will be loaded, since it is saved to the file entered by the user, which is the value of the corresponding output. Do not use the load() method in your script algorithms, but just when working with the console line. If a layer is created as output of an algorithm, it should be declared as such. Otherwise, you will not be able to properly use the algorithm in the modeler, since its syntax (as defined by the tags explained above) will not match what the algorithm really creates. Hidden outputs (numbers and strings) do not have a value. Instead, it is you who has to assign a value to them. To do so, just set the value of a variable with the name you used to declare that output. For instance, if you have used this declaration, ##average=output number

the following line will set the value of the output to 5: average = 5

In addition to the tags for parameters and outputs, you can also define the group under which the algorithm will be shown, using the group tag. If you algorithm takes a long time to process, it is a good idea to inform the user. You have a global named progress available, with two available methods: setText(text) and setPercentage(percent) to modify the progress text and the progress bar. Several examples are provided. Please, check them to see real examples of how to create algorithms using the processing framework classes. You can right-click on any script algorithm and select Edit script to edit its code or just to see it.

17.5.4 Documenting your scripts As in the case of models, you can create additional documentation for your script, to explain what they do and how to use them. In the script editing dialog you will find a [Edit script help] button. Click on it and it will take you to the help editing dialog. Check the chapter about the graphical modeler to know more about this dialog and how to use it. Help files are saved in the same folder as the script itself, adding the .help extension to the filename. Notice that you can edit your script’s help before saving it for the first time. If you later close the script editing dialog without

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saving the script (i.e. you discard it), the help content you wrote will be lost. If your script was already saved and is associated to a filename, saving is done automatically.

17.5.5 Pre- and post-execution script hooks Scripts can also be used to set pre- and post-execution hooks that are run before and after an algorithm is run. This can be used to automate tasks that should be performed whenever an algorithm is executed. The syntax is identical to the syntax explained above, but an additional global variable named alg is available, representing the algorithm that has just been (or is about to be) executed. In the General group of the processing config dialog you will find two entries named Pre-execution script file and Post-execution script file where the filename of the scripts to be run in each case can be entered.

17.6 The history manager 17.6.1 The processing history Every time you execute an algorithm, information about the process is stored in the history manager. Along with the parameters used, the date and time of the execution are also saved. This way, it is easy to track the and control all the work that has been developed using the processing framework, and easily reproduce it. The history manager is a set of registry entries grouped according to their date of execution, making it easier to find information about an algorithm executed at any particular moment.

Gambar 17.30: History Process information is kept as a command-line expression, even if the algorithm was launched from the toolbox. This makes it also useful for those learning how to use the command-line interface, since they can call an algorithm using the toolbox and then check the history manager to see how that same algorithm could be called from the command line. Apart from browsing the entries in the registry, processes can be re-executed, simply double-clicking on the corresponding entry. Along with algorithm executions, the processing framework communicates with the user using the other groups of the registry, namely Errors, Warnings and Information. In case something is not working properly, having a

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look at the Errors might help you to see what is happening. If you get in contact with a developer to report a bug or error, the information in that group will be very useful for him to find out what is going wrong. When executing third party algorithms, this is usually done calling their command-line interfaces, which communicate with the user using the console. Although that console is not shown, a full dump of it is stored in the Information group each time you run one of those algorithms. If, for instance, you are having problems executing a SAGA algorithm, look for an entry name ‘SAGA execution console output’ to check all the messages generated by SAGA and try to find out where the problem is. Some algorithms, even if they can produce a result with the given input data, might add comments or additional information to Warning block in case they detect potential problems from that data, in order to warn you about them. Make sure you check those messages in case you are having unexpected results.

17.7 Configuring external applications The processign framework can be extended using additional applications. Currently, SAGA, GRASS, OTB(Orfeo Toolbox) and R are supported, along with some other command-line applications that provide spatial data analysis functionalities. Algorithms relying on an external application are managed by their own algorithm provider. This chapter will show you how to configure the processing framework to include these additional applications, and will explain some particular features of the algorithm based on them. Once you have correctly configured the system, you will be able to execute external algorithms from any component like the toolbox or the graphical modeler, just like you do with any other geoalgorithm. By default, all algorithms that rely on an external appplication not shipped with QGIS are not enabled. You can enable them in the configuration dialog. Make sure that the corresponding application is already installed in your system. Enabling an algorithm provider without installing the application it needs will cause the algorithms to appear in the toolbox, but an error will be thrown when you try to execute them. This is because the algorithm descriptions (needed to create the parameters dialog and provide the information needed about the algorithm) are not included with each application, but with QGIS instead. That is,they are part of QGIS, so you have them in your installation even if you have not installed any other software. Running the algorithm, however, needs the application binaries to be installed in your system.

17.7.1 A note for Windows users If you are not an advanced user and you are running QGIS on windows, you might not be interested in reading the rest of this chapter. Make sure you install QGIS in your system using the OSGeo4W application. That will automatically install SAGA, GRASS and OTB in your system, and configure them so they can be run from QGIS. All the algorithms in the simplified view of the toolbox will be ready to be run, without needing any further configuration. If you want to know more about how these providers work, or want to use some algorithms not included in the simplified toolbox (such as R scripts), keep on reading.

17.7.2 A note on file formats When using an external software, opening a file in QGIS does not mean that it can be opened and processed as well on that other software. In most cases, it can read what you have opened in QGIS, but in some cases, that might not be the case. When using databases or uncommon file formats, whether for raster of vector layers, problems might arise. If that happens, try to use well known file formats that you are sure that are understood by both programs, and check to console output (in the history and log dialog) for knowing more about what is going wrong. Using GRASS raster layers is, for instance, one case in which you might have trouble and not be able to complete your work if you call an external algorithm using such a layer as input. For this reason, these layers will not appear as available to algorithms. You should, however, find no problems at all with vector layers, since QGIS automatically converts from the original file format to one accepted by the external application before passing the layer to it. This adds an extra 180

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processing time, which might be significant if the layer has a large size, so do not be surprised if it takes more to process a layer from a DB connection that one of a similar size stored in a shapefile. Providers not using external applications can process any layer that you can open in QGIS, since they open it for analysis through QGIS. Regarding output formats, all formats supported by QGIS as output can be used, both for raster and vector layers. Some provider do not support certain formats, but all can export to common formats raster layers that can be later transformed by QGIS automatically. As in the case of input layers, if this conversion is needed, that might increase the processing time. If the extension of the filename specified when calling an algorithm does not match the extension of any of the formats supported by QGIS, then a suffix will be added to set a default format. In the case of raster layers, the tif extension is used, while shp is used for vector layer.

17.7.3 A note on vector layer selections External applications are also aware of the selection that exist in vector layers within QGIS. However, that requires rewritting all input vector layers, just as if they were originally in a format not supported by the external application. Only when no selection exist, or the Use only selected features option is not enabled in the processing general configuration, a layer can be directly passed to an external application. In other cases, exporting only selected features is needed, which causes execution times to be longer. SAGA SAGA algorithms can be run from QGIS if you have SAGA installed in your system and you configure the processing framework properly so it can find SAGA executables. In particular, the SAGA command-line executable is needed to run SAGA algorithms. In case of running Windows, the standalone installer or the OSGeo4W installer, both install SAGA along with QGIS, and the path is automatically configured, so there is no need to do anything else. If you have installed SAGA yourself (remember, you need version 2.1), the path to the SAGA executable must be configured. To do it, open the configuration dialog. In the SAGA block you will find a setting named SAGA Folder. Enter the path to the folder where SAGA is installed. Close the configuration dialog and now you are ready to run SAGA algorithms from QGIS. In case you are running linux, SAGA binaries are not included with SEXTANTE, so you have to download and install the software yourself. Please check the SAGA website for more information. SAGA 2.1 is needed. In this case there is no need to configure that, and you will not see those folders. Instead, you must make sure that SAGA is properly installed and its folder is added to the PATH environment variable. Just open a console and type saga_cmd to check that the system can find where SAGA binaries are located.

17.7.4 About SAGA grid system limitations Most of SAGA algorithms that require several input raster layers, require them to have the same grid system. That is, to cover the same geographic area and have the same cellsize, so their corresponding grids match. When calling SAGA algorithms from QGIS, you can use any layer, regardless of its cellsize and extent. When multiple raster layers are used as input for a SAGA algorithm, QGIS resamples them to a common grid system and then passes them to SAGA (unless the SAGA algorithm can operate with layers from different grid systems). The definition of that common grid system is controlled by the user, and you will find several parameters in the SAGA group of the setting window to do so. There are two ways of setting the target grid system: • Setting it manually. You define the extent setting the values of the following parameters: – Resampling min X – Resampling max X

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– Resampling min Y – Resampling max Y – Resampling cellsize Notice that QGIS will resample input layers to that extent, even if they do not overlap with it. • Setting it automatically from input layers. To select this option, just check the Use min covering grid system for resampling option. All the other settings will be ignored and the minimum extent that covers all the input layers will be used. The cellsize of the target layer is the maximum of all cellsizes of the input layers. For algorithms that do not use multiple raster layers, or for those that do not need a unique input grid system, no resampling is performed before calling SAGA, and those parameters are not used.

17.7.5 Limitations for multi-band layers Unlike QGIS, SAGA has no support for multi-band layers. If you want to use a multiband layer (such as an RGB or multispectral image), you first have to split it into single-banded images. To do so, you can use the ‘SAGA/Grid - Tools/Split RGB image’ algorithm (which creates 3 images from an RGB image) or the ‘SAGA/Grid - Tools/Extract band’ algorithm (to extract a single band).

17.7.6 Limitations in cellsize SAGA assumes that raster layers have the same cellsize in the X and Y axis. If you are working with a layer with different values for its horizontal and vertical cellsizes, you might get unexcepted results. In this case, a warning will be added to the processing log, indicating that an input layer might not be suitable to be processed by SAGA.

17.7.7 Logging When QGIS calls SAGA, it does it using its command-line interface, thus passing a set of commands to perform all the required operation. SAGA show its progress by writing information to the console, which includes the percentage of processing already done, along with additional content. This output is filtered and used to update the progress bar while the algorithm is running. Both the commands sent by QGIS and the additional information printed by SAGA can be logged along with other processing log messages, and you might find them useful to track in detailed what is going on when QGIS runs a SAGA algorithm. you will find two settings, namely Log console output and Log execution commands to activate that logging mechanism. Most other providers that use an external application and call it through the command-line have similar options, so you will find them as well in other places in the processing settings list. R. Creating R scripts R integration in QGIS is different from that of SAGA in that there is not a predefined set of algorithms you can run (except for a few examples). Instead, you should write your scripts and call R commands, much like you would do from R, and in a very similar manner to what we saw in the chapter dedicated to processing scripts. This chapter shows you the syntax to use to call those R commands from QGIS and how to use QGIS objects (layers, tables) in them. The first thing you have to do, as we saw in the case of SAGA, is to tell QGIS where you R binaries are located. You can do so using the R folder entry in the processing configuration dialog. Once you have set that parameter, you can start creating your own R scripts and executing them. Once again, this is different in Linux, and you just have to make sure that the R folder is included in the PATH environment variable. If you can start R just typing R in a console, then you are ready to go.

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To add a new algorithm that calls an R function (or a more complex R script that you have developed and you would like to have available from QGIS), you have to create a script file that tells the processing framework how to perform that operation and the corresponding R commands to do so. Script files have the extension .rsx and creating them is pretty easy if you just have a basic knowledge of R syntax and R scripting. They should be stored in the R-scripts folder. You can set this folder in the R settings group (available from the processing settings dialog), just like you do with the folder for regular processing scripts. Let’s have a look at a very simple file script file, which calls the R method spsample to create a random grid within the boundary of the polygons in a given polygon layer. This method belong to the maptools package. Since almost all the algorithms that you might like to incorporate into QGIS will use or generate spatial data, knowledge of spatial packages like maptools and, specially, sp, is mandatory. ##polyg=vector ##numpoints=number 10 ##output=output vector ##sp=group pts=spsample(polyg,numpoints,type="random") output=SpatialPointsDataFrame(pts, as.data.frame(pts))

The first lines, which start with a double Python comment sign (##), tell QGIS the inputs of the algorithm described in the file and the outputs that it will generate. They work exactly with the same syntax as the SEXTANTE scripts that we have already seen, so they will not be described here again. Check the processing_scripts section for more information. When you declare an input parameter, QGIS uses that information for two things: creating the user interface to ask the user for the value of that parameter and creating a corresponding R variable that can be later used as input for R commands. In the above example, we are declaring an input of type vector named polyg. When executing the algorithm, QGIS will open in R the layer selected by the user and store it in a variable also named polyg. So the name of a parameter is also the name of the variable that we can use in R for accesing the value of that parameter (thus, you should avoid using reserved R words as parameter names). Spatial elements such as vector and raster layers are read using the readOGR() and brick() commands (you do not have to worry about adding those commands to your description file, QGIS will do it) and stored as Spatial*DataFrame objects. Table fields are stored as strings containing the name of the selected field. Tables are opened using the read.csv() command. If a table entered by the user is not in CSV format, it will be converted prior to importing it in R. Additionally, raster files can be read using the readGDAL() command instead of brick(), by using the ##usereadgdal. If you are an advanced user and do not want QGIS to create the object representing the layer, you can use the ##passfilename tag to indicate that you prefer a string with the filename instead. In this case, it is up to you to open the file before performing any operation on the data it contains. With the above information, we can now understand the first line of our first example script (the first line not starting with a Python comment). pts=spsample(polyg,numpoints,type="random")

The variable polygon already contains a SpatialPolygonsDataFrame object, so it can be used to call the spsample method, just like the numpoints one, which indicates the number of points to add to the created sample grid. Since we have declared an output of type vector named out, we have to create a variable named out and store a Spatial*DataFrame object in it (in this case, a SpatialPointsDataFrame). You can use any name for your intermediate variables. Just make sure that the variable storing your final result has the same name that you used to declare it, and contains a suitable value. In this case, the result obtained from the spsample method has to be converted explicitly into a SpatialPointsDataFrame object, since it is itself an object of class ppp, which is not a suitable class to be returned to QGIS.

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If your algorithm generates raster layers, the way they are saved will depend on whether you have used or not the #dontuserasterpackage option. In you have used it, layers are saved using the writeGDAL() method. If not, the writeRaster() method from the raster package will be used. If you have used the #passfilename option, outputs are generated using the raster package (with writeRaster()), even though it is not used for the inputs. If you algorithm does not generate any layer, but a text result in the console instead, you have to indicate that you want the console to be shown once the execution is finished. To do so, just start the command lines that produce the results you want to print with the > (‘greater’) sign. The output of all other lines will not be shown. For instance, here is the description file of an algorithm that performs a normality test on a given field (column) of the attributes of a vector layer: ##layer=vector ##field=field layer ##nortest=group library(nortest) >lillie.test(layer[[field]])

The output ot the last line is printed, but the output of the first is not (and neither are the outputs from other command lines added automatically by QGIS). If your algorithm creates any kind of graphics (using the plot() method), add the following line: ##showplots

This will cause QGIS to redirect all R graphical outputs to a temporary file, which will be later opened once R execution has finished. Both graphics and console results will be shown in the processing results manager. For more information, please check the script files provided with SEXTANTE. Most of them are rather simple and will greatly help you understand how to create your own ones. Catatan: rgdal and maptools libraries are loaded by default so you do not have to add the corresponding library() commands (you have to make sure, however, that those two packages are installed in your R distribution). However, other additional libraries that you might need have to be explicitly loaded. Just add the necessary commands at the beginning of your script. You also have to make sure that the corresponding packages are installed in the R distribution used by QGIS. The processing framework will not take care of any package installation. If you run a script that requires an uninstalled package, the execution will fail, and SEXTANTE will try to detect which packages are missing. You must install those missing libraries manually before you can run the algorithm.

GRASS Configuring GRASS is not much different from configuring SAGA. First, the path to the GRASS folder has to be defined, but only if you are running Windows. Additionaly, a shell interpreter (usually msys.exe, which can be found in most GRASS for Windows distributions) has to be defined and its path set up as well. By default, the processign framework tries to configure its GRASS connector to use the GRASS distribution that ships along with QGIS. This should work without problems in most systems, but if you experience problems, you might have to do it manually. Also, if you want to use a different GRASS installation, you can change that setting and point to the folder where that it is installed. GRASS 6.4 is needed for algorithms to work correctly. If you are running Linux, you just have to make sure that GRASS is correctly installed, and that it can be run without problem from a console. GRASS algorithms use a region for calculations. This region can be defined manually using values similar to the ones found in the SAGA configuration, or automatically, taking the minimum extent that covers all the input layers used to execute the algorithm each time. If this is the behaviour you prefer, just check the Use min covering region option in the GRASS configuration parameters.

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The last parameter that has to be configured is related to the mapset. A mapset is needed to run GRASS, and the processing frmaework creates a temporary one for each execution. You have to specify if the data you are working with uses geographical (lat/lon) coordinates or projected ones. GDAL No additional configuration is needed to run GDAL algorithms, since it is already incorporated to QGIS and algorithms can infere its configuration from it. Orfeo ToolBox Orfeo ToolBox (OTB) algorithms can be run from QGIS if you have OTB installed in your system and you have configured QGIS properly, so it can find all necessary files (command-line tools and libraries). As in the case of SAGA OTB binaries are included in the standalone installer for Windows, but are not included if you are runing Linux, so you have to download and install the software yourself. Please check the OTB website for more information. Once OTB is installed, start QGIS, open the processing configuration dialog and configure the OTB algorithm provider. In the Orfeo Toolbox (image analysis) block you will find all settings related to OTB. First ensure that algorithms are enabled. Then configure the path to the folder where OTB command–line tools and libraries are installed: •

usually OTB applications folder point to /usr/lib/otb/applications and OTB command line tools folder is /usr/bin

•

if you use OSGeo4W installer, than install otb-bin package and enter C:\OSGeo4W\apps\orfeotoolbox\applications as OTB applications folder and C:\OSGeo4W\bin as OTB command line tools folder. This values should be configured by default, but if you have a different OTB installation, configure them to the correspondig values in your system.

TauDEM To use this provider you need to install TauDEM command line tools.

17.7.8 Windows Please visit TauDEM homepage for installation instructions and precompiled binaries for 32bit and 64bit systems. IMPORTANT: you need TauDEM 5.0.6 executables, version 5.2 is currently not supported.

17.7.9 Linux There are no packages for most Linux distribution, so you should compile TauDEM by yourself. As TauDEM uses MPICH2, first install it using your favorite package manager. Also TauDEM works fine with OpenMPI, so you can use it instead of MPICH2. Download TauDEM 5.0.6 source code and extract files in some folder. Open linearpart.h file and add after line #include "mpi.h"

add new line with #include

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so you’ll get #include "mpi.h" #include

Save changes and close file. Now open tiffIO.h, find line #include "stdint.h" and replace quotes ("") with , so you’ll get #include

Save changes and close file. Create build directory and cd into it mkdir build cd build

Configure your build with command CXX=mpicxx cmake -DCMAKE_INSTALL_PREFIX=/usr/local ..

and then compile make

Finaly, to install TauDEM into /usr/local/bin, run sudo make install

17.8 The SEXTANTE Commander SEXTANTE includes a practical tool that allows you to run algorithms without having to use the toolbox, but just typing the name of the algorithm you want to run. This tools is known as the SEXTANTE commander, and it is just a simple text box with autocompletion where you type the command you want to run.

Gambar 17.31: The SEXTANTE Commander The commander is started from the Analysis menu or, more practically, pressing Shift + Ctrl + M (you can change that default keyboard shortcut in the QGIS configuration if you prefer a different one). Apart from executing SEXTANTE algorithms, the commander gives you access to most of the functionality in QGIS, which means that it gives you a practical and efficient way of running QGIS tasks, and allows you to control QGIS reducing the usage of buttons and menus. Moreover, the commander is configurable and you can add your custom commands and have them just a few keystrokes away, making it a powerful tool to become more productive in your daily work with QGIS

17.8.1 Available commands The commands available in the commander fall in the following categories: 186

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• SEXTANTE algorithms. algorithm>.

They are shown as SEXTANTE algorithm:

0. Furthermore you can also activate the Print as raster checkbox. This means all elements will be rastered before printing or saving as Postscript or PDF. Select/Move item • The Item Properties tab displays the properties for the selected item element. Click the icon to select an element (e.g. legend, scalebar or label) on the canvas. Then click the Item Properties tab and customize the settings for the selected element.

• The Command history tab (hidden by default) displays a history of all changes applied to the print composer layout. With a mouse click it is possible to undo and redo layout steps back and forth to a certain status.

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• The Atlas generation tab allows to enable the generation of an atlas for the current composer and gives access to its parameters. You can add multiple elements to the composer. It is also possible to have more than one map view or legend or scalebar in the print composer canvas, on one or several pages. Each element has its own properties and in the case of the map, its own extent. If you want to remove any elements from the composer canvas you can do that with the Delete or the Backspace key. Navigation tools To navigate in the canvas layout, the print composer provides 4 general tools: •

Zoom in

•

Zoom out

•

Zoom to full extend

•

Refresh the view

(if you find the view in an inconsistent state)

18.1.3 Composition tab — General composition setup In the Composition tab, you can define the global settings of your composition. • You can choose one of the Presets for your papersheet, or enter your custom width and height. • Composition can now be parted on several pages. For instance, a first page can show a map canvas and a second page will show the attribute table associated to a layer while a third ons shows a HTML frame linking to your organization website. Set the Number of pages to the desired value. • Choose the page Orientation and its Exported resolution • When checked, the Postscript or PDF.

print as raster means all elements will be rasterized before printing or saving as

• Snap to grid and Snap to alignements tools make accomplishing some tasks much easier. There’s three types of grid: Dots, Solid lines and Crosses. You can adjust spacings, offsets and color to your need. • Selection tolerance defines the maximum distance below which an item is snapped to the grid. • Snap to alignements shows helping lines when the borders or axis of two items are aligned.

18.1.4 Composer items general options Composer items have a set of common properties you will find on the bottom of the Item Properties tab: Position and size, Frame, Background, Item ID and Rendering (See figure_composer_2) • The Position and size dialog lets you define size and position of the frame that contains the item. You can also choose which Reference point will be set at the X and Y coordinates previously defined. • The Frame shows or hides the frame around the label. Click on the [Color] and [Thickness] buttons to adjust those properties. • the Background enables or disables a background color. Click on the [Color...] button to display a dialog where you pick a color ou choose frome a custom setting. Transparency can also be adjusted throught the alpha field. • Use the Item ID to create a relationship to other print composer items. • Rendering mode can be selected in the option field. See Rendering_Mode .

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Gambar 18.2: Common Item properties Dialogs

18.2 Rendering mode QGIS now allows advanced rendering for composer items just like vector and raster layers.

Gambar 18.3: Rendering mode • Transparency : you can make the underlying item in the composer visible with this tool. Use the slider to adapt the visibility of your item to your needs. You can also make a precise definition of the percentage of visibility in the the menu beside the slider. • Blending mode: you can achieve special rendering effects with these tools that you previously only know from graphics programs. The pixels of your overlaying and underlaying items are mixed through the settings described below. – Normal: This is the standard blend mode which uses the alpha channel of the top pixel to blend with the Pixel beneath it; the colors aren’t mixed – Lighten: It selects the maximum of each component from the foreground and background pixels. Be aware that the results tend to be jagged and harsh. – Screen: Light pixels from the source are painted over the destination, while dark pixels are not. This mode is most useful for mixing the texture of one layer with another layer. E.g. you can use a hillshade to texture another layer – Dodge: Dodge will brighten and saturate underlying pixels based on the lightness of the top pixel. So brighter top pixels cause the saturation and brightness of the underlying pixels to increase. This works best if the top pixels aren’t too bright, otherwise the effect is too extreme. – Addition: This blend mode simply adds pixel values of one layer with the other. In case of values above 1 (in the case of RGB), white is displayed. This mode is suitable for highlighting features.

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– Darken: Creates a resultant pixel that retains the smallest components of the foreground and background pixels. Like lighten, the results tend to be jagged and harsh – Multiply: It multiplies the numbers for each pixel of the top layer with the corresponding pixel for the bottom layer. The results are darker pictures. – Burn: Darker colors in the top layer causes the underlying layers to darken. Can be used to tweak and colorise underlying layers. – Overlay: Combines multiply and screen blending modes. In the resulting picture light parts of the picture become lighter and dark parts become darker. – Soft light: Very similar to overlay, but instead of using multiply/screen it uses color burn/dodge. This one is supposed to emulate shining a soft light onto an image. – Hard light: Hard light is very similar to the overlay mode. It’s supposed to emulate projecting a very intense light onto an image. – Difference: Difference subtracts the top pixel from the bottom pixel or the other way round, to always get a positive value. Blending with black produces no change, as values for all colors are 0. – Subtract: This blend mode simply subtracts pixel values of one layer with the other. In case of negative values, black is displayed.

18.3 Composer Items 18.3.1 Adding a current QGIS map canvas to the Print Composer Add new map toolbar button in the print composer toolbar to add the QGIS map canvas. Now drag a Click on the rectangle on the composer canvas with the left mouse button to add the map. To display the current map, you can choose between three different modes in the map Item Properties tab:

• Rectangle is the default setting. It only displays an empty box with a message ‘Map will be printed here’. • Cache renders the map in the current screen resolution. If case you zoom in or out the composer window, the map is not rendered again but the image will be scaled. • Render means, that if you zoom in or out the composer window, the map will be rendered again, but for space reasons, only up to a maximum resolution. Cache is default preview mode for newly added print composer maps. Select/Move item button, selecting the element, and dragging You can resize the map element by clicking on the one of the blue handles in the corner of the map. With the map selected, you can now adapt more properties in the map Item Properties tab. Move item content To move layers within the map element select the map element, click the icon and move the layers within the map element frame with the left mouse button. After you found the right place for an element, you can lock the element position within the print composer canvas. Select the map element and click on the right Lock

mouse button to activating the

the element position and again to unlock the element. You can lock the map element also

Lock layers for map item checkbox in the Map dialog of the Item Properties tab.

Main properties The Main properties dialog of the map Item Properies tab provides following functionalities (see figure_composer_4): • The Preview area allows to define the preview modes ‘Rectangle’, ‘Cache’ and ‘Render’, as described above. If you change the view on the QGIS map canvas by zooming or panning or changing vector or raster

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Gambar 18.4: Map Item properties Tab properties, you can update the print composer view selecting the map element in the print composer and clicking the [Update preview] button. • The field Scale

sets a manual scale.

• The field Rotation allows to rotate the map element content clockwise in degrees. Note, a coordinate frame can only be added with the default value 0. • The Draw map canvas items lets you show annotations that may be placed on the map canvas in the main QGIS window. • You can choose to lock the layers shown on a map item. Check the Lock layers for map item. Any layer that would be displayed or hidden in the main QGIS window after checked on won’t appear or be hidden in the map item of the composer. But style and labels of a locked layer is still refreshed accordingly to the main QGIS interface. Extents The Extents dialog of the map item tab provides following functionalities (see Figure figure_composer_5):

Gambar 18.5: Map Extents Dialog

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• The Map extent area allow to specify the map extent using Y and X min/max values or clicking the [Set to map canvas extent] button. If you change the view on the QGIS map canvas by zooming or panning or changing vector or raster properties, you can update the print composer view selecting the map element in the print composer and clicking the [Update preview] button in the map Item Properties tab (see Figure figure_composer_2). Grid The Grid dialog of the map Item Properties tab provides following functionalities (see Figure_composer_6):

Gambar 18.6: Map Grid Dialog

• The Show grid checkbox allows to overlay a grid to the map element. As grid type you can specify to use solid line or cross. Symbology of the grid can be chosen. See Section Rendering_Mode. Furthermore you can define an interval in X and Y direction, an X and Y offset, and the width used for cross or line grid type. • You can choose to paint the frame with a Zebra style. If not selected, general frame option is used (See Section Frame_dialog) Advanced rendering mode is also available for grids. See Section Rendering_mode) • The Draw coordinates checkbox allows to add coordinates to the map frame. The annotation can be drawn inside or outside the map frame. The annotation direction can be defined as horizontal, vertical, horizontal and vertical, or boundary direction, for each border individually. Units can be in meters or in degrees. Finally you can define the grid color, the annotation font, the annotation distance from the map frame and the precision of the drawn coordinates. Overview The Overview dialog of the map Item Properties tab provides following functionalities (see Figure_composer_7): If the composer has more than one map, you can choose to use a map to show the extents of a second map. The Overview dialog of the map Item Properties tab allows to customize the appearance of that feature. • The Overview frame combolist references the map item whose extents will be drawn on the present map item. • The Overview Style allows to change the frame color. See Section vector_style_manager .

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Gambar 18.7: Map Overview Dialog • The Overview Blend mode allows different transparency blend modes, to enhance visibility of the frame. See Rendering_Mode Invert overview creates a mask around the extents : the referenced map extents are shown • If checked, the clearly whereas everything else is blended with the frame color.

18.3.2 Adding a Label item to the Print Composer Add label To add a label, click the icon, place the element with the left mouse button on the print composer canvas and position and customize its appearance in the label Item Properties tab.

The Item Properties tab of a Label item provides following functionalities:

Gambar 18.8: Label Item properties Tab

Main properties The Main properties dialog of the Label Item Properties tab provides following functionalities (see Figure_composer_9): • The Main properties dialog is where is inserted the text (html or not) or the expression needed to fill the label added to the composer canvas. • Labels can be interpreted as html code: check the Render as HTML. You can now insert a url, an clickable image that link to a web page or something more complex. • You can also insert an expression. Click on the [Insert an expression] to open a new dialog. Build an expression by clicking the functions available in the left side of the panel. On the right side of the Insert an expression dialog is displayed the help file associated with the function selected. Two special categories can be useful, particularly associted with the Atlas functionnality : geometry functions and records functions. On the bottom side, a preview of the expression is shown.

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Gambar 18.9: Label Main properties Dialog • Define font and font color by clicking on the [Font] and [Font color...] buttons Alignment and Display The Alignment and Display dialogs of the Label Item Properties tab provide following functionalities (see Figure_composer_10):

Gambar 18.10: Label Alignment and Display Dialogs • You can define the horizontal and vertical alignment in the Alignment zone • In the Display tag, you can define a margin in mm and/or a rotation angle in degrees for the text.

18.3.3 Adding an Image item to the Print Composer Add image To add an image, click the icon, place the element with the left mouse button on the print composer canvas and position and customize its appearance in the image Item Properties tab.

The image Item Properties tab provides following functionalities (see figure_composer_11): Main properties, Search directories and Rotation The Main properties and Search directories dialogs of the Image Item Properties tab provide following functionalities (see Figure_composer_12): 18.3. Composer Items

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Gambar 18.11: Image Item properties Tab

Gambar 18.12: Image Main properties, Search directories and Rotation Dialogs

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• The Main properties dialog shows the current image that is displayed in the image item. Click on the [...] button to select a file on your computer. • This dialog shows all pictures stored in the selected directories. • The Search directories area allows to add and remove directories with images in SVG format to the picture database. • Image can be rotate, with the Rotation

field.

• Activating the Sync with map checkbox synchronizes the rotation of a picture in the QGIS map canvas (i.e. a rotated north arrow) with the appropriate print composer image.

18.3.4 Adding a Legend item to the Print Composer Add new legend icon, place the element with the left mouse button on the print To add a map legend, click the composer canvas and position and customize their appearance in the legend Item Properties tab.

The Item properties of a legend item tab provides following functionalities (see figure_composer_14):

Gambar 18.13: Legend Item properties Tab

Main properties The Main properties dialog of the legend Item Properties tab provides following functionalities (see figure_composer_14):

Gambar 18.14: Legend Main properties Dialog • Here you can adapt the legend title. • Choose which Map item the current legend will refer to in the select list. • Since QGIS 1.8, you can wrap the text of the legend title to a given character. 18.3. Composer Items

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Legend items The Legend items dialog of the legend Item Properties tab provides following functionalities (see figure_composer_15):

Gambar 18.15: Legend Legend Items Dialog • The legend items window lists all legend items and allows to change item order, group layers, remove and restore items of the list, edit layer names. After changing the symbology in the QGIS main window you can click on [Update] to adapt the changes in the legend element of the print composer. The item order can be changed using the [Up] and [Down] buttons or with ‘drag and drop’ functionality. • The feature count for each vector layer can be shown by enable the [Sigma] button. • Legend can be updated automatically,

Auto-update is checked.

Fonts, Columns, Symbol and Spacing The Fonts, Columns, Symbol and Spacing dialogs of the legend Item Properties tab provide following functionalities (see figure_composer_16): • You can change the font of the legend title, group, subgroup and item (layer) in the legend item. Click on a category button to open a Select font dialog. • All those items will get the same Color • Legend items can be arranged in several columns. Select the correct value in the Count

field.

• The

Equal columns widths sets how legend columns should be adjusted.

• The

Split layers option allows a categorized or a graduated layer legend to be divided upon columns.

• You can change width and height of the legend symbol in this dialog. • Spacing aroung title, group, subgroup, symbol, icon label, box space or column space can be customized throught that dialog.

18.3.5 Adding a Scalebar item to the Print Composer Add new scalebar To add a scalebar, click the icon, place the element with the left mouse button on the print composer canvas and position and customize their appearance in the scalebar Item Properties tab.

The Item properties of a scalebar item tab provides following functionalities (see figure_composer_17):

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Gambar 18.16: Legend Fonts, Columns, Symbol and Spacing Dialogs

Gambar 18.17: Scalebar Item properties Tab

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Main properties The Main properties dialog of the scalebar Item Properties tab provides following functionalities (see figure_composer_18):

Gambar 18.18: Scalebar Main properties Dialog • First choose the map the scalebar will be attached to. • then choose the style of your scalebar. Six styles are available : • Single box and Double box styles which contain one or two lines of boxes alternating colors, • Middle, Up or Down line ticks, • Numeric : the scale ratio is printed, i.e. 1:50000. Units and Segments The Units and Segments dialogs of the scalebar Item Properties tab provide following functionalities (see figure_composer_19):

Gambar 18.19: Scalebar Units and Segments Dialogs In those two dialogs, you can set how the scalebar will be represented. • Select the map units used. There’s three possible choices : Map Units is the automated unit selection, Meters or Feet force unit conversions. • The Label field defines the text used to describe the unit of the scalebar. • The Map units per bar unit allows to fix the ratio between a map unit and its representation in the scalebar. • You can define how many Segments will be drawn on the left and on the right side of the scalebar, and how long will be each segment (Size field). Height can also be defined. Display, Fonts and colors The Display and Fonts and colors dialogs of the scalebar Item Properties tab provide following functionalities (see figure_composer_20):

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Gambar 18.20: Scalebar Display, Fonts and colors Dialogs • You can define how the scalebar will be displayed in its frame. Adjust the Box margin between text and frame borders, Labels margin between text and scalebar drawing and the Line width of the scalebar drawing. • The Alignment in the Display dialog only applies to Numeric styled scalebars and puts text on the left, middle or right side of the frame.

18.3.6 Adding a Basic shape or Arrow item to the Print Composer It is possible to add basic shapes (Ellipse, Rectangle, Triangle) and arrows to the print composer canvas : click the Add basic shape

Add Arrow icon or the icon, place the element with the left mouse button on the print composer canvas and position and customize their appearance in the Item Properties tab.

The Shape Item properties tab allows to draw an ellipse, rectangle, or triangle in the print composer canvas. You can define its outline and fill color, the outline width and a clockwise rotation.

Gambar 18.21: Shape Item properties Tab The Arrow Item properties tab allows to draw an arrow in the print composer canvas. You can define color, outline and arrow width and it is possible to use a default marker and no marker and a SVG marker. For the SVG marker you can additionally add a SVG start and end marker from a directory on your computer.

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Gambar 18.22: Arrow Item properties Tab Main properties • For Basic shapes, this dialog allows you to choose a Ellipse, Rectangle or Triangle shape and its rotation. • Unlike the other items, line style, line color and background color of a basic shape are adjusted with the Frame and Background dialog. No frame is drawn. • For arrows, you can define here the line style : Color, Line width and Arrow head width. • Arrows markers can be adjusted. If you want to set a SVG Start marker and/or End marker, browse to your SVG file by clicking on the [...] button after selecting SVG radio button. Catatan: Unlike other items, background color for a basic shape is the shape background and not the frame one.

18.3.7 Add attribute table values to the Print Composer Add attribute table It is possible to add parts of a vector attribute table to the print composer canvas : click the icon, place the element with the left mouse button on the print composer canvas and position and customize their appearance in the Item Properties tab.

The Item properties of a attribute table item tab provides following functionalities (see figure_composer_23):

Gambar 18.23: Scalebar Item properties Tab

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Main properties, Show grid and Fonts The Main properties, Show grid and Fonts dialogs of the attribute table Item Properties tab provide following functionalities (see figure_composer_24):

Gambar 18.24: Attribute table Main properties, Show grid and Fonts Dialog

Gambar 18.25: Attribute table Select attributes Dialog • The Table dialog allows to select the vector layer and columns of the attribute table. Attribute columns can be sorted and you can define to show its values ascending or descending (see figure_composer_25). • You can choose to display only the attribute of features visibled on a map. Check features and select the corresponding Composer map to filter.

Show only visible

• You can define the Maximum number of rows to be displayed and margin around text. • Additionally you can define the grid characteristics of the table (Stroke width and Color of the grid) and the header and content font.

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18.3.8 Add a HTML frame to the Print Composer Add html frame icon, place the element with the It is possible to add a clickable frame, linked to an URL : click the left mouse button on the print composer canvas and position and customize their appearance in the Item Properties tab.

Main properties The Main properties dialog of the HTML frame Item Properties tab provides following functionalities (see figure_composer_26):

Gambar 18.26: HTML frame Item properties Tab • Point the URL field to the URL or the HTML file you want to insert in the composer. • You can adjust the rendering of that page with the Resize mode. • Use existing frames constraints the page inside its first frame or in the frame created with the next settings. • Extent to next page will create as many frames (and their pages) as necessary to render the height of the webpage. Each frame can be moved around on the layout. If you resize a frame, the webpage will be divided up upon the other frames. The last frame will be trimmed to fit the webpage. • Repeat on every page will first repeat the upper left of the webpage on every page, in same sized frames. • Repeat until finished will also create as many frames as the Extend to next page option, except All frames will have the same size.

18.4 Item alignment Raise selected items Raise or lower functionalities for elements are inside the pulldown menu. Choose an element on the print composer canvas and select the matching functionality to raise or lower the selected element compared to the other elements (see table_composer_1). Align selected items There are several alignment functionalities available within the pulldown menu (see table_composer_1). To use an alignment functionality , you first select some elements and then click on the matching alignment icon. All selected will then be aligned within to their common bounding box. When moving items on the composer canvas, alignment helper lines appear when borders, centers or corners are aligned.

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Gambar 18.27: Alignment helper lines in the Print Composer

18.4.1 Revert and Restore tools During the layout process it is possible to revert and restore changes. This can be done with the revert and restore tools: •

Revert last changes

•

Restore last changes

or by mouse click within the Command history tab (see figure_composer_28).

Gambar 18.28: Command history in the Print Composer

18.5 Atlas generation The print composer includes generation functions that allow to create map books in an automated way. The concept is to use a coverage layer, which contains geometries and fields. For each geometry in the coverage layer, a new output will be generated where the content of some canvas maps will be moved to highlight the current geometry. Fields associated to this geometry can be used within text labels. There can only be one atlas map by print composer but this one can contain multiple pages. Every pages will be generated with each feature. To enable the generation of an atlas and access generation parameters, refer to the Atlas generation tab. This tab contains the following widgets (see Figure_composer_29): • A

Generate an atlas enables or disables the atlas generation.

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Gambar 18.29: Atlas generation tab

• A combobox Composer map that allows to choose which map item will be used as the atlas map, i.e. on which map geometries from the coverage layer will be iterated over and displayed. • A combobox Coverage layer which to iterate over.

that allows to choose the (vector) layer containing the geometries on

• An optional Hidden coverage layer, that if checked, will hide the coverage layer (but not the other ones) during the generation. • An optional Features sorting that, if checked, allows to sort features of the coverage layer. The associated combobox allows to choose which column will be used as the sorting key. Sort order (either ascending or descending) is set by a two-state button that displays an up or a down arrow. • An optional Feature filtering text area that allows to specify an expression for filtering features from the coverage layer. If the expression is not empty, only features that evaluate to True will be selected. The button on the right allows to display the expression builder. • An input box Scaling that allows to select the amount of space added around each geometry within the allocated map. Its value is meaningful only when using the autoscaling mode. • A Fixed scale that allows to toggle between auto-scale and fixed-scale mode. In fixed scale mode, the map will only be translated for each geometry to be centered. In auto-scale mode, the map’s extents are computed in such a way that each geometry will appear in its whole. • An Output filename expression textbox that is used to generate a filename for each geometry if needed. It is based on expressions. This field is meaningful only for rendering to multiple files. • A Single file export when possible that allows to force the generation of a single file if this is possible by the chosen output format (PDF for instance). If this field is checked, the value of the Output filename expression field is meaningless. In order to adapt labels to the feature the atlas plugin iterates over, use a label with this special notation [%expression using field_name%]. For example, with a city layer with fields CITY_NAME and ZIPCODE, you could insert this : “[% ‘The area of ‘ || upper(CITY_NAME) || ‘,’ || ZIPCODE || ‘ is ‘ format_number($area/1000000,2) || ‘ km2’ %]“ And that would result in the generated atlas as

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“The area of PARIS,75001 is 1.94 km2”.

18.5.1 Generation The atlas generation is done when the user asks for a print or an export. The behaviour of these functions will be slightly changed if an atlas map has been selected. For instance, when the user asks for an export to PDF, if an atlas map is defined, the user will be asked for a directory where to save all the generated PDF files (except if the Single file export when possible has been selected).

18.6 Creating Output Figure_composer_30 shows the print composer with an example print layout including each type of map element described in the sections above.

Gambar 18.30: Print Composer with map view, legend, image, scalebar, coordinates , text and HTML frame added

The print composer allows you to create several output formats and it is possible to define the resolution (print quality) and paper size: Print • The icon allows to print the layout to a connected printer or a Postscript file depending on installed printer drivers.

• The JPG,...

Export as image

• The

Export as PDF

saves the defined print composer canvas directly as a PDF.

• The

Export as SVG

icon saves the print composer canvas as a SVG (Scalable Vector Graphic).

icon exports the composer canvas in several image formats such as PNG, BPM, TIF,

Catatan: Currently the SVG output is very basic. This is not a QGIS problem, but a problem of the underlaying Qt library. This will hopefully be sorted out in future versions. Export big raster can sometimes fail, even if there seems to be enough memory. This is also a problem of the underlaying Qt management of raster.

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18.7 Manage the Composer Save as template Load from template and icons you can save the current state of a print composer session With the as a .qpt template and load the template again in another session. Composer Manager The button in the QGIS toolbar and in Composer → Composer Manager allows to add a new composer template, create a new composition based on a previously saved template or to manage already existing templates.

Gambar 18.31: The Print Composer Manager By default, the composer manager searches for user templates in ~/.qgis2/composer_template. New Composer Duplicate Composer The and buttons in the QGIS toolbar and in Composer → New Composer and Composer → Duplicate Composer allow to open a new composer dialog, or to duplicate an existing composition from a previously created one. Save Project button. This is the same feature as in the QGIS Finally you can save your print composition with the main window. All changes will be saved in a QGIS project file.

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BAB 19

Plugin

19.1 Plugin QGIS QGIS telah dirancang dengan arsitektur plugin. Hal ini memungkinkan banyak fitur baru / fungsi dapat dengan mudah ditambahkan ke aplikasi. Banyak fitur di QGIS benar-benar diterapkan sebagai salah satu inti atau plugin eksternal. • Plugin Inti dikelola oleh Tim Pengembang QGIS dan secara otomatis bagian dari setiap distribusi QGIS. Ditulis dalam salah satu dari dua bahasa: C++ atau Python. Informasi lebih lanjut tentang plugin inti disediakan dalam Bagian Menggunakan QGIS Plugin Inti • Plugin Eksternal saat ini semua ditulis dengan Python. Mereka disimpan dalam repositori eksternal dan Get more Bagian dari Plugin Manager. dipelihara oleh penulis individu. Dapat ditambahkan ke QGIS di Informasi lebih lanjut tentang plugin eksternal disediakan dalam Bagian Memuat Plugin eksternal QGIS.

19.1.1 Mengelola Plugin Mengelola plugin secara umum berarti bongkar atau muat dengan menggunakan Plugin Manager. Untuk menonaktifkan dan mengaktifkan plugin eksternal, Plugin Manager digunakan kembali. Memuat QGIS Plugin Inti Memuat QGIS Plugin Inti dilakukan dari menu utama Plugins → Install Plugins.

Manage and Install Plugins. Manage and

Menu Installed dari daftar Plugin Manager semua plugin yang tersedia dan status mereka (dimuat atau dibongkar), termasuk semua plugin inti dan semua plugin eksternal yang telah dipasang dan diaktifkan secara otomatis dengan menggunakan

menu Get more (lihat Bagian Memuat Plugin eksternal QGIS). Plugin yang sudah

dimuat memiliki tanda centang di sebelah kiri nama mereka. Figure_plugins_1 menunjukkan

Installed dialog.

Untuk mengaktifkan plugin inti tertentu, klik kotak centang di sebelah kiri nama plugin dan klik [OK]. Ketika Anda keluar dari aplikasi, daftar plugin yang dimuat tetap dipertahankan, dan plugin secara otomatis dimuat. Memuat Plugin eksternal QGIS Plugin Eksternal QGIS ditulis dengan Python. Secara tetap disimpan baik dalam Repositori ‘Resmi’ QGIS, atau dalam berbagai repositori eksternal lainnya yang dikelola oleh masing-masing penulis. Anda dapat menemukan plugin eksternal dalam menu

Get more.

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Gambar 19.1: Pengelola Plugin

In the Installed menu you can see the path if it is an external plugin. External plugins are only installed in your home directory while core plugins are stored in /usr . Dokumentasi rinci tentang penggunaan, minimum versi QGIS, homepage, penulis, dan informasi penting lainnya yang disediakan untuk Repositori ‘Resmi’ QGIS di http://plugins.qgis.org/plugins/. Untuk repositori eksternal lainnya, mungkin tersedia dengan plugin eksternal sendiri. Secara umum tidak termasuk dalam panduan ini. Saat ini ada lebih dari 150 plugin eksternal yang tersedia di Repositori ‘Resmi’ QGIS. Beberapa plugin ini menawarkan fungsi yang akan dibutuhkan oleh banyak pengguna (contoh: menyediakan pengguna dengan kemampuan untuk melihat dan mengedit data OpenStreetMap, atau untuk menambahkan lapisan GoogleMap) sementara yang lain menawarkan fungsi yang sangat khusus (contoh: menghitung diameter pipa untuk jaringan pasokan air). Hal ini, bagaimanapun, cukup mudah untuk mencari semua plugin eksternal yang tersedia dengan menggunakan kata kunci, memilih nama repositori dan/atau menyaring pada status plugin (saat ini terpasang atau dihapus dalam sistem Anda). Pencarian dan penyaringan dilakukan dari Pemasang Plugin Python QGIS Tip: Tambah repositori Untuk menambah repositori penulis eksternal, buka Pemasang Plugin

Manage and Install Plugins, ke menu

Settings, dan klik [Tambah] (lihat figure_plugins_2). Jika Anda tidak ingin salah satu atau lebih dari repositori ditambahkan, dapat dinonaktifkan melalui tombol [Sunting...], atau benar-benar dihapus dengan tombol [Hapus]. Dengan demikian, kita tidak bisa bertanggung jawab untuk mereka. Anda juga dapat mengelola daftar repositori secara manual, yaitu menambah, menghapus, dan mengedit data. Tip: Periksa Pembaruan Anda tetap dapat informasi tentang plugin. Aktifkan kotak centang

Check for updates on startup dari menu

Settings. QGIS akan memberitahu Anda setiap kali sebuah plugin atau pembaruan plugin tersedia.

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Gambar 19.2: Pengaturan Plugin

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19.2 Menggunakan QGIS Plugin Inti Ikon Plugin

Deskripsi

Referensi Panduan

Tangkapan Koordinat

Tetikus menangkap koordinat di CRS yang berbeda

:ref:‘coordcapt

Pengelola DB

Mengelola basis data Anda dengan QGIS

Plugin Pengelola DB

Pengubah DXF2Shape

Mengubah berkas format dari DXF ke SHP

Plugin Pengonversi Dxf2Shp

eVis

Alat Visualisasi

eVis Plugin

fTools

Perangkat alat vektor

Plugin fTools

Perangkat GPS

Alat untuk bongkar impor data GPS

GPS Plugin

GRASS

Fungsionalitas GRASS

GRASS GIS Integration

Alat GDAL

Fungsionalitas raster GDAL

Plugin Alat GDAL

Pemberi Georeferensi GDAL

Georeferensi Raster dengan GDAL

Plugin Georeferencer

Heatmap

Membuat heatmap raster dari memasukkan titik vektos

Heatmap Plugin

Plugin Interpolasi

Interpolasi pada dasar simpul dari lapisan vektor

Plugin Interpolasi

Menyunting di luar jaringan

Penyuntingan di luar jaringan dan sinkronisasi dengan basis data

Plugin Mengedit Diluar Jaringan (Offline)

Oracle Spasial Georaster

Akses Oracle Spasial GeoRaster

Oracle GeoRaster Plugin

Pengelola Plugin

Mengelola inti dan plugin eksternal

Mengelola Plugin

Analisis Raster Terrain

Fitur menghitung geomorfologi dari DEM

Plugin Raster Analisis Terrain

Plugin Grafik Jalan

Analisis jalur terpendek

Plugin Grafik Jalan

Plugin SQL Anywhere

Akses SQL dimanapun DB

Plugin SQL Anywhere

Query Spasial

Query spasial pada vektor

Plugin Spasial Query

Statistik Zonal

Hitung statistik raster untuk poligon vektor

Plugin Statistik Zonal

19.3 Plugin Mengambil Koordinat Plugin Mengambil Koordinat mudah digunakan dan memberikan kemampuan menampilkan koordinat di kanvas peta untuk dua Sistem Koordinat Referensi (CRS) dipilih. 1. Mulai QGIS, pilih

Proyek Properti dari Pengaturan (KDE, Windows) atau menu Berkas (Gnome, OSX)

dan klik pada tab Proyeksi. Sebagai alternatif, Anda juga bisa klik pada ikon bawah dari status bar.

CRS status

di sudut kanan

2. Klik pada kotak centang Aktifkan proyeksi on the fly dan pilih proyeksi sistem koordinat dari yang Anda pilih (lihat juga Working with Projections). 3. Muat plugin ambil koordinat ke dalam Manajer Plugin (see Memuat QGIS Plugin Inti) dan memastikan

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Gambar 19.3: Plugin Mengambil Koordinat

bahwa dialog terlihat dengan pergi ke Tampilan → Panel dan pastikan bahwa Ambil Koordinat udah aktif. Dialog ambil koordinat seperti dalam gambar figure_coordinate_capture_1. Alternatif lain, Anda juga bisa ke Vektor → Ambil Koordinat dan lihat 4. Klik pada ikon atas.

Ambil Koordinat sudah aktif.

Klik pilih CRS untuk menampilkan koordinat

dan memilih CRS berbeda dari yang Anda pilih di

5. Untuk mulai mengambil koordinat, klik pada [Mulai ambil]. Sekarang Anda dapat mengklik di mana saja di kanvas peta dan plugin akan menampilkan koordinat untuk kedua CRS yang Anda pilih. 6. Untuk mengaktifkan tetikus pelacak koordinat, klik ikon

pelacak tetikus

.

7. Anda juga bisa menyalin koordinat yang dipilih ke papanklip.

19.4 Plugin Pengelola DB Plugin Pengelola DB resmi bagian dari inti QGIS dan bermaksud untuk menggantikan Plugin SPIT dan tambahan untuk mengintegrasikan semua format basisdata lain yang didukung oleh QGIS dalam satu antarmuka pengguManajer DB menyediakan beberapa fitur. Anda dapat menggeser lapisan dari Penjelajah QGIS ke na. Plugin Pengelola DB dan akan mengimpor lapisan Anda ke dalam basisdata spasial Anda. Anda dapat menggeser dan menempatkan tabel antar basisdata spasial dan mereka akan diimpor. Anda juga dapat menggunakan Pengelola DB untuk mengeksekusi query SQL terhadap basisdata spasial Anda dan kemudian melihat keluaran spasial untuk queries dengan menambahkan hasilnya ke QGIS sebagai lapisan query.

Menu Basisdata memungkinkan untuk terhubung ke basisdata yang sudah ada, untuk memulai SQL-Window dan untuk keluar dari Plugin Pengeloa DB. Satu Anda terhubung ke basisdata yang sudah ada, menu Skema dan Tabel tambahan muncul. Menu Skema termasuk alat untuk membuat dan menghapus (kosong) skema dan, jika topologi tersedia (seperti PostGIS 2) untuk memulai TopoViewer. Menu Tabel memungkinkan untuk membuat dan mengedit tabel dan menghapus tabel dan tampilan. Hal ini juga memungkinkan untuk mengosongkan tabel dan untuk memindahkan tabel dari skema satu ke skema lain. Seperti fungsionalitas lebih lanjut Anda dapat melakukan VACUUM dan kemudian ANALYZE untuk setiap tabel yang dipilih. VACUUM sederhana mengambil kembali ruang dan membuatnya tersedia untuk digunakan kembali dan ANALYZE update statistik untuk menentukan cara yang paling efisien untuk mengeksekusi query. Akhirnya Anda dapat mengimpor lapisan/berkas, jika mereka dimuat dalam QGIS atau ada dalam sistem berkas. Dan Anda dapat mengekspor tabel basisdata untuk Shape dengan fitur Ekspor berkas. Jendela Tree daftar semua database yang ada didukung oleh QGIS. Dengan doble-klik Anda bisa koneksi ke basisdata. Dengan tombol tetikus-kanan Anda bisa mengubah nama dan menghapus skema dan tabel yang ada. Tabel juga dapat ditambahkan ke kanvas QGIS dengan menu konteks. Jika terkoneksi ke sebuah basisdata, jendela utama dari Pengelola DB menyediakan tiga tab. Tab Info memberikan informasi tentang tabel dan geometri serta tentang kolom yang ada, Kendala dan Indeks. Hal ini juga memungkinkan untuk menjalankan Vacuum Analis dan untuk membuat indeks spasial pada tabel yang dipilih,

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Gambar 19.4: Dialog Pengelola DB jika belum melakukannya. Tab Tabel menampilkan semua atribut dan tab Pratinjau render geometri sebagai pratinjau..

19.5 Plugin Pengonversi Dxf2Shp Plugin pengonversi dxf2shape dapat digunakan untuk mengkonversi data vektor dari DXF ke format Shapefile. Hal ini membutuhkan parameter berikut harus ditentukan sebelum menjalankan:

Gambar 19.5: Plugin Pengonversi Dxf2Shp • Masukan berkas DXF: Masukkan path ke berkas DXF yang akan dikonversi • Keluaran berkas SHP: Masukkan nama yang diinginkan dari Shapefile yang akan dibuat • Keluaran tipe berkas: Tentukan jenis geometri keluaran Shapefile. Saat ini jenis yang didukung adalah polyline, polygon, dan titik. • Ekspor label teks: Ketika kotak centang ini diaktifkan, lapisan titik Shapefile tambahan akan dibuat, dan tabel dbf terkait akan berisi informasi tentang kolom “TEXT” yang ditemukan dalam berkas DXF, dan teks string mereka sendiri.

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19.5.1 Menggunakan Plugin 1. Mulai QGIS, muat plugin Dxf2Shape di Manajer Plugin (lihat Bagian Memuat QGIS Plugin Inti) dan klik Pengonversi Dxf2Shape yang muncul di menu toolbar QGIS. Dialog plugin Dxf2Shape akan muncul pada ikon seperti Figure_dxf2shape_1.

2. Masukkan berkas DXF, nama untuk keluaran Shapefile dan jenis Shapefile. 3. Aktifkan kotak centang

Ekspor teks label jika Anda ingin membuat lapisan titi ekstra dengan label.

4. Klik [OK].

19.6 eVis Plugin The Biodiversity Informatics Facility at the American Museum of Natural History’s (AMNH) Center for Biodiversity and Conservation (CBC) (this section is derived from Horning, N., K. Koy, P. Ersts. 2009. eVis (v1.1.0) User’s Guide. American Museum of Natural History, Center for Biodiversity and Conservation. Available from http://biodiversityinformatics.amnh.org/, and released under the GNU FDL.) has developed the Event Visualization Tool (eVis), another software tool to add to the suite of conservation monitoring and decision support tools for guiding protected area and landscape planning. This plugin enables users to easily link geocoded (i.e., referenced with latitude and longitude or X and Y coordinates) photographs, and other supporting documents, to vector data in QGIS. eVis is now automatically installed and enabled in new versions of QGIS, and as with all plugins, it can be disabled and enabled using the Plugin Manager (See Mengelola Plugin). The eVis plugin is made up of three modules: the ‘Database Connection tool’, ‘Event ID tool’, and the ‘Event Browser’. These work together to allow viewing of geocoded photographs and other documents that are linked to features stored in vector files, databases, or spreadsheets.

19.6.1 Event Browser The Event Browser module provides the functionality to display geocoded photographs that are linked to vector features displayed in the QGIS map window. Point data, for example, can be from a vector file that can be input using QGIS or it can be from the result of a database query. The vector feature must have attribute information associated with it to describe the location and name of the file containing the photograph and, optionally, the compass direction the camera was pointed when the image was acquired. Your vector layer must be loaded into QGIS before running the Event Browser. Launch the Event Browser module eVis Event Browser To launch the Event browser module either click on the icon or click on Database → eVis → eVis Event Browser. This will open the Generic Event Browser window.

The Event Browser window has three tabs displayed at the top of the window. The Display tab is used to view the photograph and its associated attribute data. The Options tab provides a number of settings that can be adjusted to control the behavior of the eVis plugin. Lastly, the Configure External Applications tab is used to maintain a table of file extensions and their associated application to allow eVis to display documents other than images. Understanding the Display window To see the Display window click on the Display tab in the Event Browser window. The Display window is used to view geocoded photographs and their associated attribute data. 1. Display window: A window where the photograph will appear.

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Gambar 19.6: The eVis display window 2. Zoom in button: Zoom in to see more detail. If the entire image cannot be displayed in the display window, scroll bars will appear on the left and bottom sides of the window to allow you to pan around the image. 3. Zoom out button: Zoom out to see more area. 4. Zoom to full extent button: Displays the full extent of the photograph. 5. Attribute information window: All of the attribute information for the point associated with the photograph being viewed is displayed here. If the file type being referenced in the displayed record is not an image but is of a file type defined in the Configure External Applications tab then when you double-click on the value of the field containing the path to the file the application to open the file will be launched to view or hear the contents of the file. If the file extension is recognized the attribute data will be displayed in green. 6. Navigation buttons: Use the Previous and Next buttons to load the previous or next feature when more than one feature is selected. Understanding the Options window

Gambar 19.7: The eVis Options window

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1. File path: A dropdown list to specify the attribute field that contains the directory path or URL for the photographs or other documents being displayed. If the location is a relative path then the checkbox must be clicked. The base path for a relative path can be entered in the Base Path text box below. Information about the different options for specifying the file location are noted in the section Specifying the location and name of a photograph below. 2. Compass bearing: A dropdown list to specify the attribute field that contains the compass bearing associated with the photograph being displayed. If compass bearing information is available it is necessary to click the checkbox below the dropdown menu title. 3. Compass offset: Compass offsets can be used to compensate for declination (adjust bearings collected Manual radiobutton to enter the offset in the using magnetic bearings to true north bearings). Click the text box or click the From Attribute radiobutton to select the attribute field containing the offsets. For both of these options east declinations should be entered using positive values and west declinations should use negative values. 4. Directory base path: The base path onto which the relative path defined in Figure_eVis_2 (A) will be appended. 5. Replace path: If this checkbox is checked, only the file name from the A will be appended to the Base Path. 6. Apply rule to all documents: If checked, the same path rules that are defined for photographs will be used for non-image documents such as movies, text documents, and sound files. If not checked the path rules will only apply to photographs and other documents will ignore the Base Path parameter. 7. Remember settings: If the checkbox is checked the values for the associated parameters will be saved for the next session when the window is closed or when the [Save] button below is pressed. 8. Reset values: Resets the values on this line to the default setting. 9. Restore defaults: This will reset all of the fields to their default settings. It has the same effect as clicking all of the [Reset] buttons. 10. Save: This will save the settings without closing the Options pane. Understanding the Configure External Applications window

Gambar 19.8: The eVis External Applications window 1. File reference table: A table containing file types that can be opened using eVis. Each file type needs a file extension and the path to an application that can open that type of file. This provides the capability of opening a broad range of files such as movies, sound recordings, and text documents instead of only images. 2. Add new file type: Add a new file type with a unique extension and the path for the application that can open the file. 3. Delete current row: Delete the file type highlighted in the table and defined by a file extension and a path to an associated application.

19.6.2 Specifying the location and name of a photograph The location and name of the photograph can be stored using an absolute or relative path or a URL if the photograph is available on a web server. Examples of the different approaches are listed in Table evis_examples. 19.6. eVis Plugin

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X 780596 780596 780819

Y 1784017 1784017 1784015

780596

1784017

FILE C:\Workshop\eVis_Data\groundphotos\DSC_0168.JPG /groundphotos/DSC_0169.JPG http://biodiversityinformatics.amnh.org/\ evis_testdata/DSC_0170.JPG pdf:http://www.testsite.com/attachments.php?\ attachment_id-12

BEARING 275 80 10 76

19.6.3 Specifying the location and name of other supporting documents Supporting documents such as text documents, videos, and sound clips can also be displayed or played by eVis. To do this it is necessary to add an entry in the file reference table that can be accessed from the Configure External Applications window in the Generic Event Browser that matches the file extension to an application that can be used to open the file. It is also necessary to have the path or URL to the file in the attribute table for the vector layer. One additional rule that can be used for URLs that don’t contain a file extension for the document you want to open is to specify the file extension before the URL. The format is — file extension:URL. The URL is preceded by the file extension and a colon, and is particularly useful for accessing documents from Wikis and other web sites that use a database to manage the web pages (see Table evis_examples).

19.6.4 Using the Event Browser When the Event Browser window opens a photograph will appear in the display window if the document referenced in the vector file attribute table is an image and if the file location information in the Options window is properly set. If a photograph is expected and it does not appear it will be necessary to adjust the parameters in the Options window. If a supporting document (or an image that does not have a file extension recognized by eVis) is referenced in the attribute table the field containing the file path will be highlighted in green in the attribute information window if that file extension is defined in the file reference table located in the Configure External Applications window. To open the document double-click on the green-highlighted line in the attribute information window. If a supporting document is referenced in the attribute information window and the file path is not highlighted in green then it will be necessary to add an entry for the file’s filename extension in the Configure External Applications window. If the file path is highlighted in green but does not open when double-clicked it will be necessary to adjust the parameters in the Options window so the file can be located by eVis. If no compass bearing is provided in the Options window a red asterisk will be displayed on top of the vector feature that is associated with the photograph being displayed. If a compass bearing is provided then an arrow will appear pointing in the direction indicated by the value in the compass bearing display field in the Event Browser window. The arrow will be centered over the point that is associated with the photograph or other document. To close the Event Browser window click on the [Close] button from the Display window.

19.6.5 Event ID Tool The ‘Event ID’ module allows you to display a photograph by clicking on a feature displayed in the QGIS map window. The vector feature must have attribute information associated with it to describe the location and name of the file containing the photograph and optionally the compass direction the camera was pointed when the image was acquired. This layer must be loaded into QGIS before running the ‘Event ID’ tool. Launch the Event ID module Event ID icon or click on Database → eVis → Event ID To launch the ‘Event ID’ module either click on the Tool. This will cause the cursor to change to an arrow with an ‘i’ on top of it signifying that the ID tool is active.

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To view the photographs linked to vector features in the active vector layer displayed in the QGIS map window, move the Event ID cursor over the feature and then click the mouse. After clicking on the feature, the Event Browser window is opened and the photographs on or near the clicked locality are available for display in the browser. If more than one photograph is available, you can cycle through the different features using the [Previous] and [Next] buttons. The other controls are described in the ref:evis_browser section of this guide.

19.6.6 Database connection The ‘Database Connection’ module provides tools to connect to and query a database or other ODBC resource, such as a spreadsheet. eVis can directly connect to four types of databases:PostgreSQL, MySQL, SQLite, and can also read from ODBC connections (e.g.MS Access). When reading from an ODBC database (such as an Excel spreadsheet) it is necessary to configure your ODBC driver for the operating system you are using. Launch the Database Connection module eVis Database Connection or click To launch the ‘Database Connection’ module either click on the appropriate icon on Database → eVis → Database Connection. This will launch the Database Connection window. The window has three tabs: Predefined Queries, Database Connection, and SQL Query. The Output Console window at the bottom of the window displays the status of actions initiated by the different sections of this module.

Connect to a database Click on the Database Connection tab to open the database connection interface. Next, use the Database Type combobox to select the type of database that you want to connect to. If a password or username is required, that information can be entered in the Username and Password textboxes. Enter the database host in the Database Host textbox. This option is not available if you selected ‘MS Access’ as the database type. If the database resides on your desktop you should enter “localhost”. Enter the name of the database in the Database Name textbox. If you selected ‘ODBC’ as the database type, you need to enter the data source name. When all of the parameters are filled in, click on the [Connect] button. If the connection is successful, a message will be written in the Output Console window stating that the connection was established. If a connection was not established you will need to check that the correct parameters were entered above. 1. Database Type: A dropdown list to specify the type of database that will be used. 2. Database Host: The name of the database host. 3. Port The port number if a MySQL or PostgreSQL database type is selected. 4. Database Name The name of the database. 5. Connect A button to connect to the database using the parameters defined above. 6. Output Console The console window where messages related to processing are displayed. 7. Username: Username for use when a database is password protected. 8. Password: Password for use when a database is password protected. 9. Predefined Queries: Tab to open the “Predefined Queries” window. 10. Database Connection: Tab to open the “Database Connection” window. 11. SQL Query: Tab to open the “SQL Query” window. 12. Help: Displays the on line help. 13. OK: Close the main “Database Connection” window.

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Gambar 19.9: The eVis Database connection window Running SQL queries SQL queries are used to extract information from a database or ODBC resource. In eVis the output from these queries is a vector layer added to the QGIS map window. Click on the SQL Query tab to display the SQL query interface. SQL commands can be entered in this text window. A helpful tutorial on SQL commands is available at http://www.w3schools.com/sql. For example, to extract all of the data from a worksheet in an Excel file, select * from [sheet1$] where sheet1 is the name of the worksheet. Click on the [Run Query] button to execute the command. If the query is successful a Database File Selection window will be displayed. If the query is not successful an error message will appear in the Output Console window. In the Database File Selection window, enter the name of the layer that will be created from the results of the query in the Name of New Layer textbox. 1. SQL Query Text Window: A screen to type SQL queries. 2. Run Query: Button to execute the query entered in the SQL Query Window. 3. Console Window: The console window where messages related to processing are displayed. 4. Help: Displays the on line help. 5. OK: Closes the main Database Connection window. Use the X Coordinate and Y Coordinate comboboxes to select the field from the database that store the X (or longitude) and Y (or latitude) coordinates. Clicking on the [OK] button causes the vector layer created from the SQL query to be displayed in the QGIS map window. To save this vector file for future use, you can use the QGIS ‘Save as...’ command that is accessed by right clicking on the layer name in the QGIS map legend and then selecting ‘Save as...’ Tip: Creating a vector layer from a Microsoft Excel Worksheet

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Gambar 19.10: The eVis SQL query tab When creating a vector layer from a Microsoft Excel Worksheet you might see that unwanted zeros (“0”) have been inserted in the attribute table rows beneath valid data.This can be caused by deleting the values for these cells in Excel using the Backspace key. To correct this problem you need to open the Excel file (you’ll need to close QGIS if there if you are connected to the file to allow you to edit the file) and then use Edit → Delete to remove the blank rows from the file. To avoid this problem you can simply delete several rows in the Excel Worksheet using Edit → Delete before saving the file.

Running predefined queries With predefined queries you can select previously written queries stored in XML format in a file. This is particularly helpful if you are not familiar with SQL commands. Click on the Predefined Queries tab to display the predefined query interface. Open File To load a set of predefined queries click on the icon. This opens the Open File window which is used to locate the file containing the SQL queries. When the queries are loaded their titles, as defined in the XML

file, will appear in the dropdown menu located just below the displayed in the text window under the dropdown menu.

Open File

icon, the full description of the query is

Select the query you want to run from the dropdown menu and then click on the SQL Query tab to see that the query has been loaded into the query window. If it is the first time you are running a predefined query or are switching databases, you need to be sure to connect to the database. Click on the [Run Query] button in the SQL Query tab to execute the command. If the query is successful a Database File Selection window will be displayed. If the query is not successful an error message will appear in the Output Console window. 1. Open File: Launches the “Open File” file browser to search for the XML file holding the predefined queries. 2. Predefined Queries: A dropdown list with all of the queries defined by the predefined queries XML file.

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Gambar 19.11: The eVis Predefined queries tab 3. Query description: A short description of the query. This description is from the predefined queries XML file. 4. Console Window: The console window where messages related to processing are displayed. 5. Help: Displays the on line help. 6. OK: Closes the main “Database Connection” window. XML format for eVis predefined queries The XML tags read by eVis

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Tag Description query Defines the beginning and end of a query statement. shortdeA short description of the query that appears in the eVis dropdown menu. scription descripA more detailed description of the query displayed in the Predefined Query text window. tion databaseThe database type as defined in the Database Type dropdown menu in the Database Connection type tab. databaseThe port as defined in the Port textbox in the Database Connection tab. port databaseThe database name as defined in the Database Name textbox in the Database Connection tab. name databaseuser-The database username as defined in the Username textbox in the Database Connection tab. name databasep- The database password as defined in the Password textbox in the Database Connection tab. assword sqlstateThe SQL command. ment autoconA flag (“true”” or “false”) to specify if the above tags should be used to automatically connect to nect database without running the database connection routine in the Database Connection tab. A complete sample XML file with three queries is displayed below:

Import all photograph points This command will import all of the data in the SQLite database to QGIS

SQLITE

C:\textbackslash Workshop/textbackslash eVis\_Data\textbackslash PhotoPoints.db

SELECT Attributes.*, Points.x, Points.y FROM Attributes LEFT JOIN Points ON Points.rec_id=Attributes.point_ID false

Import photograph points "looking across Valley" This command will import only points that have photographs "looking across a valley" to QGIS SQLITE

C:\Workshop\eVis_Data\PhotoPoints.db

SELECT Attributes.*, Points.x, Points.y FROM Attributes LEFT JOIN Points ON Points.rec_id=Attributes.point_ID where COMMENTS=’Looking across valley’ false

Import photograph points that mention "limestone" This command will import only points that have photographs that mention "limestone" to QGIS SQLITE

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C:\Workshop\eVis_Data\PhotoPoints.db

SELECT Attributes.*, Points.x, Points.y FROM Attributes LEFT JOIN Points ON Points.rec_id=Attributes.point_ID where COMMENTS like ’%limestone%’

false

19.7 Plugin fTools Tujuan dari plugin fTools python adalah untuk menyediakan sumber daya one-stop untuk banyak tugas GIS umum berbasis vektor, tanpa perlu perangkat lunak tambahan, perpustakaan, atau workarounds kompleks. Ini menyediakan paket pengelolaan data spasial dan fungsi analisis yang baik cepat dan fungsional. fTools sekarang otomatis terpasang dan aktif dalam QGIS versi terbaru, dan seperti semua plugin, bisa dinonaktifkan dan diaktifkan menggunakan Pengelola Plugin (Lihat Bagian Memuat QGIS Plugin Inti). Ketika diaktifkan, plugin fTools menambahkan menu Vektor ke QGIS, menyediakan fungsi mulai dari Peralatan Analisis dan Riset ke Peralatan Geometri dan Geoprocessing, serta beberapa Peralatan Tata Kelola Data yang berguna.

19.7.1 Alat Analisis Ikon Alat

Kegunaan

Jarak Matriks

Ukur jarak antara dua lapisan titik, dan hasil keluarannya a) Matriks jarak Square, b) Matriks jarak Linear, atau c) Ringkasan dari jarak. Dapat membatasi jarak ke k fitur terdekat.

Sum panjang garis

Hitung jumlah total garis panjang untuk setiap poligon dari lapisan vektor poligon.

Poin di poligon

Hitung jumlah poin yang terjadi pada setiap poligon dari masukan lapisan vektor poligon.

Daftar nilai unik

Daftar semua nilai unik di dalam masukan kolom lapisan vektor

Dasar statistik

Hitung statistik dasar (rata-rata, std dev, N, sum, CV) pada koom masukan.

Analisis Tetangga Terdekat

Menghitung Statistik tetangga terdekat, menilai tingkat pengelompokan dalam lapisan titik vektor

Koordinat Mean

Hitung pusat rata-rata normal atau tertimbang dari seluruh lapisan vektor, atau beberapa fitur berdasarkan kolom ID unik.

Persimpangan garis

Cari persimpangan antara garis, dan hasil keluaran sebagai titik shapefile. Berguna untuk mencari persimpangan jalan atau sungai, mengabaikan persimpangan garis dengan panjang > 0.

Tabel Ftools 1: fTools Analysis tools

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19.7.2 Peralatan Riset Ikon Alat

Kegunaan

Seleksi Random

Secara acak memilih nomor n dari fitur, atau persentase n dari fitur

Seleksi acak dalam subset

Secara acak memilih fitur dalam subset berdasarkan kolom ID unik.

Poin Acak

Menghasilkan poin pseudo-acak atas masukan lapisan yang diberikan.

Poin reguler

Menghasilkan kotak biasa dari poin atas wilayah tertentu dan ekspor mereka sebagai titik shapefile.

Kotak vektor

Menghasilkan kotak garis atau poligon yang didasarkan pada pengguna jaringan jarak tertentu.

Pilih dari lokasi

Pilih fitur berdasarkan lokasi relatif mereka terhadap lapisan lain untuk membentuk pilihan baru, atau menambah atau mengurangi dari pilihan saat ini.

Poligon dari lapisan batas

Buat layer poligon persegi panjang tunggal dari luasnya sebuah masukan lapisan raster atau lapisan vektor.

Tabel Ftools 2: fTools Research tools

19.7.3 Peralatan Geoprocessing Ikon Alat

Kegunaan

Convex hull(s)

Buat convex hull minimum untuk masukan lapisan, atau berdasarkan kolom ID.

Penyangga

Buat penyangga sekitar fitur berdasarkan jarak, atau kolom jarak.

Memotong

Tampilan lapisan-lapisan seperti keluaran berisi daerah di mana kedua lapisan berpotongan.

Penggabungan

Tampilan lapisan-lapisan seperti keluaran berisi daerah berpotongan dan non-berpotongan.

Perbedaan simetrik

Tampilan lapisan seperti keluaran berisi daerah-daerah dari masukan dan perbedaan lapisan yang tidak berpotongan.

Klip

Tampilan lapisan seperti keluaran berisi daerah yang bersinggungan lapisan klip.

Perbedaan

Tampilan lapisan seperti keluaran yang berisi daerah yang tidak memotong lapisan klip.

Larut

Menggabungkan fitur berdasarkan masukan bidang. Semua fitur dengan nilai masukan yang identik digabungkan untuk membentuk satu fitur tunggal.

Menghilangkan poligon sepotong

Menggabungkan fitur yang dipilih dengan poligon tetangga dengan daerah terbesar atau batas umum terbesar.

Tabel Ftools 3: fTools Peralatan Geoprocessing

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19.7.4 Peralatan Geometri Ikon Alat

Kegunaan

Periksa validitas geometri

Periksa poligon untuk persimpangan, ditutup-lubang, dan memperbaiki pengurutan node.

Ekspor/Tambah kolom geometri

Tambah lapisan vektor geometri ke lapisan poin (XCOORD, YCOORD), garis (LENGTH), atau poligon (AREA, PERIMETER).

Polygon centroids

Menghitung centroid berlaku untuk setiap poligon dalam masukan lapisan poligon.

Triangulasi Delaunay Poligon Voronoi

Menghitung dan keluaran (sebagai poligon) triangulasi Delaunay dari masukan lapisan vektor titik. Menghitung poligon voronoi dari masukan lapisan vektor.

Sederhanakan geometri Geometri densify

Generalisasi garis atau poligon dengan algoritma Douglas-Peucker dimodifikasi.

Multipart ke singgelpart

Mengkonversi fitur multipart ke beberapa fitur singgelpart. Membuat poligon dan garis sederhana.

Singgelpart ke multipart

Merge beberapa fitur ke fitur tunggal berdasarkan kolom ID unik.

Poligon ke garis

Mengkonversi poligon ke garis, poligon multipart untuk beberapa garis singgelpart.

Garis ke poligon

Mengkonversi garis ke poligon, garis multi ke beberapa bagian poligon tunggal.

Ekstrak simpul

Ekstrak simpul dari lapisan garis dan poligon dan keluaran mereka sebagai poin.

Densify garis atau poligon dengan menambahkan simpul

Tabel Ftools 4: fTools Peralatan Geometri Catatan: Alat Menyederhanakan geometri dapat digunakan untuk menghapus simpul duplikat di garis dan poligon geometri, hanya mengatur parameter Menyederhanakan toleransi ke 0 dan ini akan melakukan trik.

19.7.5 Peralatan Tata Kelola Data Ikon Alat

Kegunaan

Tentukan proyeksi sekarang

Tentukan CRS untuk shapefile yang CRS belum ditetapkan.

Menggabung atribut sesuai lokasi

Menggabung dengan atribut tambahan ke lapisan vektor didasarkan pada hubungan spasial. Atribut dari satu lapisan vektor yang ditambahkan ke tabel atribut dari lapisan lain dan diekspor sebagai shapefile.

Membagi lapisan vektor

Membagi lapisan masukan ke beberapa lapisan terpisah berdasarkan masukan kolom.

Menggabung shapefile menjadi satu Membuat indeks spasial

Menggabungkan beberapa shapefile dalam folder ke dalam shapefile baru berdasarkan jenis lapisan (titik, garis, area). Buat indeks spasial untuk yang didukung format OGR.

Tabel Ftools 5: fTools Peralatan Tata Kelola Data

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19.8 Plugin Alat GDAL 19.8.1 Apakah yang dimaksud Alat GDAL? Plugin Alat GDAL menawarkan GUI untuk koleksi alat dalam Geospatial Data Abstraction Library, http://gdal.osgeo.org. Ini adalah alat manajemen raster untuk query, re-proyek, warp dan menggabungkan berbagai format raster. Juga termasuk adalah alat untuk membuat lapisan kontur (vektor), atau relief shaded dari DEM raster, dan untuk membuat vrt (Virtual Raster Tile dalam format XML) dari koleksi satu atau lebih berkas raster. Alat ini tersedia bila plugin terpasang dan diaktifkan. Perpustakaan GDAL Perpustakaan GDAL terdiri dari satu set program baris perintah, masing-masing dengan daftar besar pilihan. Pengguna nyaman dengan menjalankan perintah dari terminal dapat memilih baris perintah, dengan akses pilihan set lengkap. Plugin alat GDAL menawarkan antarmuka yang mudah ke alat-alat, memperlihatkan hanya pilihan yang paling populer.

19.8.2 Daftar dari alat-alat GDAL

Gambar 19.12: Daftar menu Alat-alat GDAL

Proyeksi Warp (Reproject)

Menetapkan proyeksi Ekstrak proyeksi

Utilitas ini merupakan mosaicing gambar, proyeksi ulang dan warping utilitas. Program ini dapat proek ulang untuk setiap proyeksi yang didukung, dan juga dapat menerapkan GCPs disimpan dengan gambar jika gambar “raw” dengan informasi kontrol. Untuk informasi lebih lanjut Anda dapat membaca di situs GDAL http://www.gdal.org/gdalwarp.html Alat ini memungkinkan menetapkan proyeksi untuk raster yang sudah bergeoreferensi tetapi informasi proyeksi keliru. Juga dengan membantu mengubah definisi proyeksi yang ada. Kedua berkas tunggal dan mode batch didukung. Untuk informasi lebih lanjut silakan kunjungi halaman utilitas di situs GDAL http://www.gdal.org/gdalwarp.html Utilitas ini membantu Anda untuk mengekstrak informasi proyeksi dari berkas masukan. Jika Anda ingin mengambil proyeksi dari seluruh direktori Anda dapat menggunakan mode Batch. Ini menciptakan kedua berkas .prj dan .wld.

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Konversi

Rasterize

Program ini membakar vektor geometri (titik, garis dan poligon) ke pita raster dari gambar raster. Vektor dibaca dari OGR yang didukung format vektor. Perhatikan bahwa data vektor harus sama sistem koordinat dengan data raster; pada proyeksi ulang fly tidak disediakan. Untuk informasi lebih lanjut lihat http://www.gdal.org/gdal_rasterize.html

Polygonize

Utilitas ini menciptakan vektor poligon untuk semua daerah piksel terhubung di raster berbagi nilai umum pixel. Setiap poligon dibuat dengan atribut yang menunjukkan nilai pixel poligon itu. Utilitas akan menciptakan keluaran sumber data vektor jika tidak sudah ada, default ke format shapefile ESRI. Lihat juga http://www.gdal.org/gdal_polygonize.html

Terjemahan

Utilitas ini dapat digunakan untuk mengkonversi data raster antar format yang berbeda, berpotensi melakukan beberapa operasi seperti subsettings, resampling, dan rescaling piksel dalam proses. Untuk informasi Anda bisa membaca di http://www.gdal.org/gdal_translate.html

RGB ke PCT

Utilitas ini akan menghitung tabel warna-pseudo yang optimal untuk citra RGB yang diberikan dengan menggunakan algoritma cut median pada RGB histogram downsampled. Kemudian mengubah gambar menjadi gambar berwarna-pseudo menggunakan tabel warna. Konversi ini menggunakan Floyd-Steinberg dithering (difusi error) untuk memaksimalkan keluaran visual gambar kualitas. Utilitas ini juga dijelaskan pada http://www.gdal.org/rgb2pct.html

PCT ke RGB

Utilitas ini akan mengkonversi sebuah pita pseudocolor pada berkas masukan ke berkas keluaran RGB dari format yang diinginkan. Untuk informasi lebih lanjut lihat http://www.gdal.org/pct2rgb.html

Ekstraksi

Kontur

Program ini menghasilkan berkas kontur vektor dari masukan data elevasi raster (DEM). Pada http://www.gdal.org/gdal_contour.html Anda bisa menemukan banyak informasi.

Clipper

Utilitas ini memungkinkan untuk klip (ekstrak bagian) raster menggunakan batas yang dipilih atau berdasarkan masker lapisan batas. Informasi lebih lanjut dapat ditemukan di http://www.gdal.org/gdal_translate.html.

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Analisis Sieve

Utilitas ini menghilangkan raster poligon lebih kecil dari ukuran ambang batas yang disediakan (dalam piksel) dan menggantikan mereka dengan nilai piksel dari tetangga poligon terbesar. Hasilnya dapat ditulis kembali ke pita raster yang sudah ada, atau disalin ke dalam sebuah berkas baru. Untuk informasi lebih lanjut, lihat http://www.gdal.org/gdal_sieve.html .

Hampir Hitam

Utilitas ini akan memindai gambar dan mencoba untuk mengatur semua piksel yang hampir hitam (atau hampir putih) di sekitar tepi persis hitam (atau putih). Hal ini sering digunakan untuk “fix up” berkurangnya kompresi foto udara sehingga warna piksel dapat diperlakukan sebagai transparan ketika mosaicing. Lihat juga http://www.gdal.org/nearblack.html .

Isi tidak ada data

Utilitas ini mengisi seleksi raster area (biasanya tidak ada data area) dengan interpolasi dari piksel yang valid di sekitar tepi area. Lihat juga http://www.gdal.org/gdal_fillnodata.html .

Kedekatan

Utilitas ini menghasilkan peta raster kedekatan menunjukkan jarak dari pusat setiap piksel ke pusat piksel terdekat diidentifikasi sebagai piksel sasaran. Target piksel adalah pada raster sumber yang nilai raster piksel di set dari nilai target piksel. Untuk informasi lebih lanjut, lihat http://www.gdal.org/gdal_proximity.html .

Kisi (Interpolasi)

Utilitas ini menciptakan kisi biasa (raster) dari data yang tersebar dibaca dari sumber data OGR. Masukan data akan diinterpolasi untuk mengisi node kisi dengan nilai-nilai, Anda dapat memilih dari berbagai metode interpolasi. Utilitas ini juga dijelaskan di situs GDAL http://www.gdal.org/gdal_grid.html .

DEM (Terrain model)

Alat untuk menganalisis dan memvisualisasikan DEM. Hal ini dapat membuat relief shaded, lereng, aspek, warna relief, Indeks Terrain Ketidakrataan, Indeks Posisi Topografi dan kekasaran peta dari setiap GDAL didukung elevasi raster. Untuk informasi lebih lanjut Anda dapat membaca pada http://www.gdal.org/gdaldem.html .

Bermacam-macam Build Virtual Raster (Katalog)

Program ini membangun VRT (Virtual Dataset) yang merupakan mosaik dari daftar masukan dataset gdal. Lihat juga http://www.gdal.org/gdalbuildvrt.html .

Gabung

Utilitas ini secara otomatis akan mosaik serangkaian gambar. Semua gambar harus dalam sistem koordinat yang sama dan memiliki sejumlah pencocokan pita, tetapi mereka mungkin tumpang tindih, dan pada resolusi yang berbeda. Di daerah-daerah tumpang tindih, gambar terakhir akan disalin lebih dari yang sebelumnya. Utilitas ini juga dijelaskan pada http://www.gdal.org/gdal_merge.html .

Informasi

Utilitas ini berisi berbagai informasi tentang GDAL didukung dataset raster. Lihat juga http://www.gdal.org/gdalinfo.html .

Gambaran Build

Indeks Tile

Utilitas gdaladdo dapat digunakan untuk membangun atau membangun kembali gambar ikhtisar untuk format berkas yang paling didukung dengan salah satu dari beberapa algoritma downsampling. Untuk informasi lebih lanjut, lihat http://www.gdal.org/gdaladdo.html . Utilitas ini membangun shapefile dengan catatan untuk setiap berkas masukan raster, atribut yang berisi nama berkas, dan geometri poligon menguraikan raster. Lihat juga http://www.gdal.org/gdaltindex.html .

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19.9 Plugin Georeferencer Plugin Georeferencer adalah alat untuk menghasilkan berkas-berkas dunia untuk raster-raster. Hal ini memungkinkan Anda untuk membuat referensi raster dengan sistem koordinat geografis atau diproyeksikan dengan menciptakan GeoTiff baru atau dengan menambahkan sebuah berkas dunia dengan gambar yang ada. Pendekatan dasar Georeferensi raster adalah untuk menemukan titik-titik pada raster Anda secara akurat dan dapat menentukan koordinat mereka. Fitur-fitur Ikon

Tujuan

Ikon

Tujuan

Buka raster

Memulai georeferensi

Menghasilkan Skrip GDAL

Muat Poin-Poin GCP

Simpan Poin GCP Sebagai

Pengaturan Transformasi

Tambah Poin

Hapus Poin

Pindahkan Poin GCP

Pan

Perbesar

Perkecil

Perbesar Ke Lapisan

Perbesaran Terakhir

Perbesar Selanjutnya

Tautan Georeferencer ke QGIS

Tautan QGIS ke Georeferencer Tabel Georeferensi 1: Alat-Alat Georeferensi

19.9.1 Prosedur biasa Sebagai koordinat X dan Y (DMS (dd mm ss.ss), DD (dd.dd) atau koordinat diproyeksikan (mmmm.mm) yang sesuai dengan titik yang dipilih pada gambar, dua alternatif prosedur dapat digunakan: • Raster itu sendiri kadang-kadang memberikan salib dengan koordinat “written” pada gambar. Dalam hal ini Anda dapat memasukkan koordinat secara manual. • Menggunakan lapisan sudah bergeoreferensi, hal ini dapat berupa data vektor atau raster yang berisi bendabenda yang sama/fitur yang Anda miliki pada gambar yang ingin Anda Georeferensi dan proyeksi. Dalam hal ini Anda dapat memasukkan koordinat dengan mengklik pada dataset referensi dimuat dalam kanvas peta QGIS. Prosedur yang biasa untuk Georeferensi gambar memilih beberapa poin pada raster, menentukan koordinat mereka, dan memilih jenis transformasi yang relevan. Berdasarkan parameter masukan dan data, plugin akan menghitung parameter berkas dunia. Semakin banyak titik koordinat Anda berikan, akan semakin baik hasilnya. Langkah pertama untuk memulai QGIS, memuat Plugin Georeferencer (lihat Bagian Memuat QGIS Plugin Inti) Georeferencer yang muncul di toolbar menu QGIS. Dialog Plugin Georeferencer muncul dan klik pada ikon seperti dalam gambar figure_georeferencer_1.

Untuk contoh ini, kita menggunakan toposheet South Dakota dari SDGS. Hal ini nantinya dapat divisualisasikan bersama dengan data dari lokasi GRASS spearfish60. Anda dapat menngunduh toposheet di sini: http://grass.osgeo.org/sampledata/spearfish_toposheet.tar.gz. Memasukkan titik-titik kontrol lapangan (GCPs) 1. Untuk memulai georeferensi sebuah raster rintisan, kita harus memuat dengan menggunakan tombol . Raster akan muncul di wilayah kerja utama dialog. Setelah raster dimuat, kita bisa mulai untuk memasukkan titik-titik acuan. 232

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Gambar 19.13: Dialog Plugin Georeferencer

Tambah Poin 2. Menggunakan tombol , menambahkan poin-poin untuk wilayah kerja utama dan memasukkan koordinat mereka (lihat Gambar figure_georeferencer_2). Untuk prosedur ini, Anda memiliki tiga pilihan:

• Klik pada poin di gambar raster dan masukkan koordinat X dan Y secara manual. dari kanvas peta • Klik pada poin gambar raster dan pilih tombol untuk menambahkan koordinat X dan Y dengan bantuan peta georeferensi sudah dimuat dalam kanvas peta QGIS.

• Dengan tombol salah.

, Anda bisa menggeser GCP di dalam jendela, jika mereka berada di tempat yang

3. Lanjutkan memasukkan titik-titik. Anda harus memiliki setidaknya 4 poin, dan semakin banyak koordinat yang dapat Anda berikan, akan semakin baik hasilnya. Ada alat tambahan pada dialog plugin untuk memperbesar dan menggeser wilayah kerja dalam rangka untuk mencari satu set titik GCP relevan.

Gambar 19.14: Tambahkan titik-titik ke gambar raster Poin-poin yang ditambahkan ke peta akan disimpan dalam sebuah berkas teks yang terpisah ([filename].points) biasanya bersama-sama dengan gambar raster. Hal ini memungkinkan kita untuk membuka kembali plugin Georeferencer di kemudian hari dan menambah poin baru atau menghapus yang sudah ada untuk mengoptimalkan hasilnya. Berkas poin berisi nilai-nilai dalam bentuk: mapX, mapY, pixelX, pixelY. Anda bisa menggunakan tombol-tombol untuk mengelola berkas.

Muat poin-poin GCP

dan

Simpan poin GCP sebagai

Pengaturan mendefinisikan transformasi Setelah Anda telah menambahkan GCPs Anda ke gambar raster, Anda harus menentukan pengaturan transformasi untuk proses georeferensi. 19.9. Plugin Georeferencer

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Gambar 19.15: Pengaturan mendefinisikan transformasi Algoritma Transformasi Tersedia Tergantung pada berapa banyak titik kontrol lapangan yang telah direkam, Anda mungkin ingin menggunakan algoritma transformasi yang berbeda. Pilihan algoritma transformasi juga tergantung pada jenis dan kualitas masukan data dan jumlah distorsi geometris Anda bersedia untuk memasukkan kepada hasil akhir. Saat ini, berikut ini Tipe-tipe Transformasi tersedia: • Algoritma Linear adalah digunakan untuk membuat berkas-dunia, dan berbeda dari algoritma yang lain, karena tidak benar-benar mengubah raster. Algoritma ini kemungkinan besar tidak akan cukup jika Anda berurusan dengan bahan yang dipindai. • Transformasi Helmert melakukan scaling dan rotasi transformasi sederhana. • Algoritma 1-3 Polynomial yang paling banyak digunakan algoritma yang diperkenalkan untuk mencocokkan sumber dan tujuan poin kontrol lapangan. Paling banyak digunakan algoritma polinomial adalah urutan kedua transformasi polinomial, yang memungkinkan beberapa kelengkungan. Urutan pertama transformasi polinomial (affine) mempertahankan collinearity dan memungkinkan scaling, terjemahan dan rotasi saja. • Algoritma Thin Plate Spline (TPS) adalah adalah metode georeferencing yang lebih modern, yang mampu memperkenalkan deformasi lokal dalam data. Algoritma ini berguna ketika kualitas asli sangat rendah sebagai rujukan geografis. • Transformasi Proyektif rotasi linear dan terjemahan koordinat. Tentukan metode Sampel ulang Jenis resampling Anda memilih kemungkinan akan tergantung pada data masukan Anda dan tujuan akhir dari latihan. Jika Anda tidak ingin mengubah statistik dari gambar, Anda mungkin ingin memilih ‘Nearest neighbour’, sedangkan ‘resampling Cubic’ kemungkinan akan memberikan hasil yang lebih rapi. Hal ini dimungkinkan untuk memilih lima metode resampling yang berbeda. 1. Nearest neighbour 2. Linear 3. Cubic

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4. Cubic Spline 5. Lanczos Tentukan pengaturan transformasi Ada beberapa opsi yang perlu didefinisikan untuk keluaran raster georeferensi. Buat berkas dunia hanya tersedia, jika Anda memutuskan untuk menggunakan jenis • Kotak centang transformasi linear, karena ini berarti bahwa gambar raster sebenarnya tidak akan berubah. Dalam hal ini, kolom Keluaran raster tidak diaktifkan, karena hanya berkas dunia baru yang akan dibuat. • Untuk semua jenis transformasi lain Anda harus mendefinisikan Keluaran raster. Sebagai default berkas baru ([filename]_modified) akan dibuat dalam folder yang sama bersama-sama dengan gambar raster asli. • Sebagai langkah berikutnya Anda harus menentukan Target SRS (Spatial Reference System) untuk georeferensi raster (lihat bagian Working with Projections), • Jika Anda ingin, Anda bisa menghasilkan peta pdf dan juga laporan pdf. Laporan ini mencakup informasi tentang parameter transformasi yang digunakan. Sebuah gambar dari residual dan daftar dengan semua GCP dan eror RMS. Atur Target Resolusi dan tentukan pixel resolusi • Selanjutnya Anda dapat mengaktifkan kotak centang dari keluaran raster. Resolusi horisontal dan vertikal default adalah 1, •

Gunakan 0 untuk transparan jika dibutuhkan bisa diaktifkan, jika pixel dengan nilai 0 akan divisualisasikan transparan. Dalam contoh toposheet kami semua bidang putih akan jadi transparan.

• Akhirnya muat di |qg| saat selesai muat keluaran raster secara otomatis ke dalam kanvas Peta QGIS ketika transformasi sudah dilakukan. Tampilkan dan menyesuaikan properti raster Mengklik ada dialog Raster properti didalam menu Pengaturan membuka properti raster dari lapisan yang ingin Anda Georeferensi. Konfigurasi georeferensi • Anda dapat menentukan apakah Anda ingin menunjukkan koordinat GCP dan/atau ID. • Sebagai unit sisa piksel dan unit peta dapat dipilih. • Untuk laporan PDF margin kiri dan kanan dapat didefinisikan dan Anda juga dapat mengatur ukuran kertas untuk peta PDF. • Akhirnya Anda bisa mengaktifkan

show georeferencer window docked.

Menjalankan transformasi Setelah semua GCPs telah dikumpulkan dan semua pengaturan transformasi didefinisikan, tekan tombol Mulai Georeferensi untuk membuat raster baru bergeoreferensi.

19.10 Plugin Interpolasi Plugin Interpolasi dapat digunakan untuk membuat interpolasi TIN atau IDW dari suatu layer vektor titik. Plugin ini sangat sederhana serta menyediakan tampilan antarmuka yang intuitif untuk membuat layer raster terinterpolasi (lihat Figure_interpolation_1). Plugin ini memerlukan parameter-parameter berikut sebelum dapat dijalankan:

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• Masukan Lapisan-lapisan Vektor: Tentukan masukan lapisan vektor titik dari daftar lapisan titik yang dimuat. Jika beberapa lapisan ditentukan, maka data dari semua lapisan yang digunakan untuk interpolasi. Catatan: Hal ini dimungkinkan untuk menyisipkan baris atau poligon untuk triangulasi, dengan menentukan “titik”, “garis struktur” atau “baris break” dalam combobox Tipe

.

• Atribut interpolasi: Pilih kolom atribut untuk digunakan dalam interpolasi atau aktifkan checkbox Gunakan koordinat-Z untuk menggunakan nilai Z yang tersimpan pada layer. • Metode Interpolasi: Pilih metode interpolasi. Pilihannya antara lain ‘Triangulated Irregular Network (TIN)’ atau ‘Inverse Distance Weighted (IDW)’. • Jumlah kolom/baris: masukkan jumlah kolom dan baris untuk file raster keluaran. • File keluaran: Masukkan nama untuk file raster yang dihasilkan. •

Tambah hasil ke proyek untuk memuat hasil kedalam kanvas peta.

Gambar 19.16: Plugin Interpolasi

19.10.1 Menggunakan plugin interpolasi 1. Mulai QGIS dan muat lapisan vektor titik (seperti elevp.csv). 2. Muat plugin interpolasi di Pengelola Plugin (lihat Bagian Memuat QGIS Plugin Inti) dan klik pada ikon Interpolasi

yang muncul dalam menu toolbar QGIS. Dialog plugin Interploasi ditunjukkan dalam Figure_interpolation_1. 3. Pilih layer masukan (seperti elevp

) dan kolom (seperti ELEV) untuk interpolasi.

4. Pilih metode interpolasi (seperti ‘Triangulated Irregular Network (TIN)’), dan masukkan ukuran sel 5000 serta isikan juga nama file keluaran (seperti, elevation_tin). 5. Klik [OK].

19.11 Plugin Mengedit Diluar Jaringan (Offline) Untuk pengumpulan data merupakan situasi umum bekerja dengan laptop atau ponsel di luar jaringan (offline) di lapangan. Setelah kembali ke jaringan, perubahan perlu disinkronkan dengan sumber data master, misalnya basisdata PostGIS. Jika beberapa orang bekerja secara bersamaan pada dataset yang sama, sulit untuk menggabungkan hasil edit dengan tangan, bahkan jika orang tidak mengubah fitur yang sama. Mengedit Offline Plugin Plugin secara otomatis melakukan sinkronisasi dengan menyalin isi dari sumber data (biasanya PostGIS atau WFS-T) ke basisdata SpatiaLite dan menyimpan suntingan luar jaringan (offline) ke tabel khusus. Setelah terhubung ke jaringan lagi, memungkinkan untuk menerapkan secara suntingan luar jaringan (offline) ke dataset induk.

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19.11.1 Menggunakan plugin • Buka beberapa lapisan vektor, misal dari sumber data PostGIS atau WFS-T • Menyimpannya sebagai proyek Konversikan ke proyek luar jaringan dan pilih lapisan untuk menyimpan. Isi dari lapisan disimpan • Tekan ikon the ke tabel SpatiaLite.

• Edit lapisan luar jaringan. • Setelah terhubung lagi, mengunggah perubahan dengan tombol

Synchronize

.

Gambar 19.17: Membuat proyek luar jaringan dari lapisan PostGIS atau WFS

19.12 Oracle GeoRaster Plugin In Oracle databases, raster data can be stored in SDO_GEORASTER objects available with the Oracle Spatial OracleGeoRasterPlugin extension. In QGIS, the is supported by GDAL, and depends on Oracle’s database product being installed and working on your machine. While Oracle is proprietary software, they provide their software free for development and testing purposes. Here is one simple example of how to load raster images to GeoRaster:

$ gdal_translate -of georaster input_file.tif geor:scott/tiger@orcl

This will load the raster into the default GDAL_IMPORT table, as a column named RASTER.

19.12.1 Managing connections Firstly, the Oracle GeoRaster Plugin must be enabled using the Plugin Manager (see Section Memuat QGIS Plugin Inti). The first time you load a GeoRaster in QGIS, you must create a connection to the Oracle database that Select GeoRaster contains the data. To do this, begin by clicking on the toolbar button, it will open the Select Oracle Spatial GeoRaster dialog window. Click on [New] to open the dialog window, and specify the connection parameters (See Figure_oracle_raster_1):

• Name: Enter a name for the database connection • Database instance: Enter the name of the database that you will connect to • Username: Specify your own username that you will use to access the database 19.12. Oracle GeoRaster Plugin

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• Password: The password associated with your username that is required to access the database

Gambar 19.18: Create Oracle connection dialog Now, back on the main Oracle Spatial GeoRaster dialog window (see Figure_oracle_raster_2), use the drop-down list to choose one connection, and use the [Connect] button to establish a connection. You may also [Edit] the connection by opening the previous dialog and making changes to the connection information, or use the [Delete] button to remove the connection from the drop-down list.

19.12.2 Selecting a GeoRaster Once a connection has been established, the sub-datasets window will show the names of all the tables that contains GeoRaster columns in that database in the format of a GDAL subdataset name. Click on one of the listed subdatasets and then click on [Select] to choose the table name. Now another list of subdatasets will show with the names of GeoRaster columns on that table. This is usually a short list, since most users will not have more than one or two GeoRaster columns on the same table. Click on one of the listed subdatasets and then click on [Select] to choose one of the the table/column combination. The dialog will now show all the rows that contains GeoRaster objects. Note that the subdataset list will now show the Raster Data Table and Raster Id’s pairs. At anytime the Selection entry can be edited in order to go directly to a known GeoRaster or to go back to the beginning and select another table name.

Gambar 19.19: Select Oracle GeoRaster dialog

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The Selection data entry can also be used to enter a WHERE clause at the end of the identification string, e.g. geor:scott/tiger@orcl,gdal_import,raster,geoid=. See http://www.gdal.org/frmt_georaster.html for more information.

19.12.3 Displaying GeoRaster Finally, by selecting a GeoRaster from the list of Raster Data Table and Raster Id’s, the raster image will be loaded into QGIS. The Select Oracle Spatial GeoRaster dialog can be closed now and next time it opens it will keep the same connection, and will show the same previous list of subdataset making it very easy to open up another image from the same context. Catatan: GeoRasters that contains pyramids will display much faster but the pyramids need to be generated outside of QGIS using Oracle PL/SQL or gdaladdo. The following is example using gdaladdo: gdaladdo georaster:scott/tiger@orcl,georaster\_table,georaster,georid=6 -r nearest 2 4 6 8 16 32

This is an example using PL/SQL: $ sqlplus scott/tiger SQL> DECLARE gr sdo_georaster; BEGIN SELECT image INTO gr FROM cities WHERE id = 1 FOR UPDATE; sdo_geor.generatePyramid(gr, ’rLevel=5, resampling=NN’); UPDATE cities SET image = gr WHERE id = 1; COMMIT; END;

19.13 Plugin Raster Analisis Terrain Plugin Raster Analisis Terrain dapat digunakan untuk menghitung kemiringan, aspek, bayangan bukit, indeks kekasaran dan relief untuk model elevasi digital (DEM). Sangat sederhana menangani dan menyediakan grafis antarmuka pengguna intuitif untuk membuat lapisan raster baru (Lihat Figure_raster_terrain_1). Deskripsi dari analisis: • Lereng: Menghitung sudut kemiringan untuk setiap sel dalam derajat (berdasarkan urutan pertama estimasi derivatif). • Aspek: Eksposisi (dimulai dengan 0 untuk arah utara, dalam derajat berlawanan jarum jam). • Bukitbayangan: Buat peta berbayang menggunakan cahaya dan bayangan untuk memberikan penampilan lebih tiga dimensi untuk peta relief berbayang. • Indeks Ketidakrataan: Sebuah pengukuran kuantitatif dari medan heterogenitas seperti yang dijelaskan oleh Riley et al. (1999). Hal ini dihitung untuk setiap lokasi, dengan meringkas perubahan elevasi dalam kisi 3x3 piksel. • Relief: Membuat peta relief berbayang dari data elevasi digital. Diimplementasikan metode memilih warna elevasi menganalisis frekuensi distribusi.

19.13.1 Menggunakan plugin 1. Mulai QGIS dan muat layer raster gtopo30 dari contoh lokasi GRASS.

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Gambar 19.20: Plugin Raster Pemodelan Terrain (perhitungan kemiringan) 2. Muat plugin Raster Analisis Terrain plugin di Pengelola Plugin (lihat Bagian Memuat QGIS Plugin Inti) 3. Pilih metode analisis dari menu (e.g. Raster → Analisis Terrain → Kemiringan). Dialog Kemiringan seperti dalam gambar Figure_raster_terrain_1. 4. Spesifikasi keluaran berkas path dan keluaran tipe berkas: 5. Klik [OK].

19.14 Heatmap Plugin The Heatmap plugin uses Kernel Density Estimation to create a density (heatmap) raster of an input point vector layer. The density is calculated based on the number of points in a location, with larger numbers of clustered points resulting in larger values. Heatmaps allow easy identification of “hotspots” and clustering of points.

19.14.1 Activate the Heatmap plugin First this core plugin needs to be activated using the Plugin Manager (see Section Memuat QGIS Plugin Inti). After activation the heatmap icon

can be found in the Raster Toolbar, and under the Raster → Heatmap menu.

Select the menu View → Toolbars → Raster to show the Raster Toolbar if it is not visible.

19.14.2 Using the Heatmap plugin Clicking the

Heatmap toolbutton opens the Heatmap plugin dialog (see figure_heatmap_2).

The dialog has the following options: • Input point layer: lists all the vector point layers in the current project and is used to select the layer to be analysed. • Output raster: use the button to select the folder and file name for the output raster the Heatmap plugin generates. A file extension is not required. • Output format: selects the output format. Although all formats supported by GDAL can be choosen, in most cases GeoTIFF is the best format to choose. • Radius: used to specify the heatmap search radius (or kernel bandwidth) in meters or map units. The radius specifies the distance around a point at which the influence of the point will be felt. Larger values result in greater smoothing, but smaller values may show finer details and variation in point density. When the

Advanced checkbox is checked additional options will be available:

• Rows and Columns: used to change the dimensions of the output raster. These values are also linked to the Cell size X and Cell size Y values. Increasing the number of rows or colums will decrease the cell size and increase the file size of the output file. The values in Rows and Columns are also linked, so doubling

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the number of rows will automatically double the number of columns and the cell sizes will also be halved. The geographical area of the output raster will remain the same! • Cell size X and Cell size Y: control the geographic size of each pixel in the output raster. Changing these values will also change the number of Rows and Columns in the output raster. • Kernel shape: The kernel shape controls the rate at which the influence of a point decreases as the distance from the point increases. Different kernels decay at different rates, so a triweight kernel gives features greater weight for distances closer to the point then the Epanechnikov kernel does. Consequently, triweight results in “sharper” hotspots, and Epanechnikov results in “smoother” hotspots. A number of standard kernel functions are available in QGIS, which are described and illustrated on Wikipedia. • Decay ratio: can be used with Triangular kernels to futher control how heat from a feature decreases with distance from the feature. – A value of 0 (=minimum) indicates that the heat will be concentrated in the centre of the given radius and be completely extinguished at the edge. – A value of 0.5 indicates that pixels at the edge of the radius will be given half the heat as pixels at the centre of the search radius. – A value of 1 means the heat is spread evenly over the whole search radius circle. (This is equivalent to the ‘Uniform’ kernel.) – A value greater than 1 indicates that the heat is higher towards the edge of the search radius then at the centre. The input point layer may also have attribute fields which can affect how they influence the heatmap: • Use radius from field: sets the search radius for each feature from an attribute field in the input layer. • Use weight from field: allows input features to be weighted by an attribute field. This can be used to increase the influence certain features have on the resultant heatmap. When an output raster file name is specified, the [OK] button can be used to create the heatmap.

19.14.3 Tutorial: Creating a Heatmap For the following example we will use the airports vector point layer from the QGIS sample dataset (see Contoh data). Another exellent QGIS tutorial on making heatmaps can be found at http://qgis.spatialthoughts.com. In Figure_Heatmap_1 the airports of Alaska are shown.

Gambar 19.21: Airports of Alaska

1. Select the

Heatmap toolbutton to open the Heatmap dialog (see Figure_Heatmap_2).

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2. In the Input point layer

field select airports from the list of point layers loaded in current project.

3. Specify an output file name by clicking the button next to the Output raster field. Enter the file name heatmap_airports (no file extension is necessary). 4. Leave the Output format as the default format, GeoTIFF. 5. Change the Radius to 1000000 meters. 6. Click on [OK] to create and load the airports heatmap (see Figure_Heatmap_3).

Gambar 19.22: The Heatmap Dialog QGIS will generate the heatmap and add the results to your map window. By default, the heatmap is shaded in greyscale, with lighter areas showing higher concentrations of airports. The heatmap can now be styled in QGIS to improve its appearance.

Gambar 19.23: The heatmap after loading looks like a grey surface 1. Open the properties dialog of the heatmap_airports layer (select the layer heatmap_airports, open the context menu with the right mouse button and select Properties). 2. Select the Style tab. 3. Change the Render type 4. Select a suitable Color map 242

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5. Click the [Load] button to fetch the minimum and maximum values from the raster, then click the [Classify] button. 6. Press [OK] to update the layer. The final result is shown in Figure_Heatmap_4.

Gambar 19.24: Styled heatmap of airports of Alaska

19.15 Plugin Grafik Jalan Plugin Grafik Jalan merupakan plugin C++ untuk QGIS, yang menghitung jalur terpendek antara dua titik pada setiap lapisan polyline dan plot jalan ini melalui jaringan jalan.

Gambar 19.25: Plugin Grafik Jalan Fitur Utama: • menghitung path, panjang dan waktu travel • Mengoptimalkan dari panjang atau dari waktu travel • ekspor path ke lapisan vektor • arah jalan highlight (ini lambat dan digunakan terutama untuk tujuan debug dan untuk pengujian pengaturan) 19.15. Plugin Grafik Jalan

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Seperti lapisan jalan Anda bisa menggunakan setiap lapisan vektor polyline dalam format yang didukung QGIS. Dua garis dengan titik umum dianggap terhubung. Harap dicatat, ini diperlukan untuk menggunakan CRS lapisan sebagai CRS proyek ketika mengedit lapisan jalan. Hal ini disebabkan fakta bahwa perhitungan koordinat antara CRS yang berbeda memperkenalkan beberapa kesalahan yang dapat mengakibatkan diskontinuitas, bahkan ketika ‘snapping’ digunakan. Dalam tabel lapisan atribut kolom berikut dapat digunakan: • kecepatan pada bagian jalan — kolom numerik; • arah — jenis, yang dapat dicor ke string. Arah maju dan mundur yang sesuai dengan jalan satu arah, dua arah — dua arah jalan Jika beberapa bidang tidak memiliki nilai apapun atau tidak ada — nilai standar yang digunakan. Anda dapat mengubah default dan beberapa pengaturan plugin di dialog pengaturan plugin.

19.15.1 Menggunakan plugin Setelah Plugin aktif Anda akan melihat sebuah panel tambahan di sisi kiri dari jendela utama QGIS. Sekarang membuat beberapa definisi dialog Pengaturan plugin grafik jalan di menu Vektor → Grafik Jalan (lihat figure_road_graph_2).

Gambar 19.26: Pengaturan plugin grafik jalan Setlah mengatur Satuan waktu, Satuan Jarak dan Toleransi topologi Anda bisa memilih lapisan vektor di tab Lapisan transportasi. Disini Anda juga bisa memilih Kolom Arah dan Kolom Kecepatan. Dalam tab Pengaturan standar Anda bisa mengatur Arah untuk menghitung. Akhirnya pada panel Shortest Path pilih mulai dan titik Berhenti di lapisan jaringan jalan dan klik [Hitung].

19.16 Plugin Spasial Query Spasial Query Plugin memungkinkan untuk membuat query spasial (pilih fitur) di lapisan sasaran dengan mengacu pada lapisan lain. Fungsi ini didasarkan pada perpustakaan GEOS dan tergantung pada sumber fitur lapisan yang dipilih.

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• Persilangan • Berpotongan • Memisah • Bersinggungan • Di dalam

19.16.1 Menggunakan plugin Sebagai contoh, kita ingin mencari daerah dalam dataset Alaska yang mengandung bandara. Langkah-langkah berikut diperlukan: 1. Mulai QGIS dan muat lapisan vektor regions.shp dan airports.shp. 2. Muat Plugin Spasial Query dari Pengelola Plugin (Lihat Bagian Memuat QGIS Plugin Inti) dan klik ikon Spasial Query

yang muncul di menu toolbar QGIS. Dialog plugin muncul.

3. Pilih lapisan regions sebagai sumber lapisan dan airports sebagai lapisan fitur referensi. 4. Pilih ‘Isi’ sebagai operator dan klik [Terapkan]. Sekarang Anda mendapatkan daftar ID fitur dari query dan Anda memiliki beberapa pilihan seperti yang ditunjukkan pada figure_spatial_query_1. • Klik pada

Buat lapisan dengan daftar item

• Pilih ID dari daftar dan klik

Buat lapisan yang dipilih

• Pilih ‘Hapus dari seleksi sekarang’ dalam kolom Dan gunakan hasilnya • Selain itu ANda juga bisa

Perbesar ke item atau tampilkan

.

Pesan Log.

Gambar 19.27: Analisis Spasial Query - regions contain airports

19.17 Plugin SQL Anywhere SQL Anywhere adalah relational database management system (RDBMS) proprietary dari Sybase. SQL Anywhere termasuk dukungan spasial antara lain OGC, shapefile dll dan dibangun dalam fungsi untuk ekspor ke KML, GML dan format SVG.

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Gambar 19.28: Dialog SQL Anywhere (KDE)

SQL Anywhere

memungkinkan untuk terhubung ke spasial basisdata SQL Anywhere aktif. Dialog Add SQL Anywhere layer mirip dalam dialog dengan fungsi untuk PostGIS dan SpatiaLite.

19.18 Topology Checker Plugin

Gambar 19.29: The Topology Checker Plugin Topology describes the relationships between points, lines and polygons that represent the features of a geographic region. With the Topology Checker plugin you can look over your vector files and check the topology with several topology rules. These rules check with spatial relations whether your features ‘Equal’, ‘Contain’, ‘Cover’, are ‘CoveredBy’, ‘Cross’, ‘Disjoint’, ‘Intersect’, ‘Overlap’, ‘Touches’ and are ‘Within’ each other. It depends on your individual questions which topology rules you apply to your vector data. E.g. normally you won’t accept overshoots in line layers but if they depict dead-end streets you won’t remove them from your vector layer. QGIS has the built-in topological editing feature which is great for creating new features without errors. But existing data errors and user induced errors are hard to find out. This plugin helps you find out such errors through a list of rules. It is very simple to create topology rules with the Topology Checker plugin. On point layers the following rules are available:

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• must be covered by: Here you can choose a vector layer from your project. Points that aren’t covered by the given vector layer occur in the ‘Error’ field • must be covered by endpoints of: Here you can choose a line layer from your project. • must be inside: Here you can choose a polygon layer from your project. The points must be inside a polygon. Otherwise QGIS writes an ‘Error’ for the point. • must not have duplicates: Whenever a point is represented twice or more it will occur in the ‘Error’ field. • must not have invalid geometries: Checks whether the geometries are valid. • must not have multi-part-geometries: All multi-part points are written into the ‘Error’ field. On line layers the following rules are available: • end points must be covered by: Here you can select a point layer from your project. • must not have dangles: This will show the overshoots in the line layer. • must not have duplicates: Whenever a line feature is represented twice or more it will occur in the ‘Error’ field. • must not have invalid geometries: Checks whether the geometries are valid. • must not have multi-part geometries: Sometimes, a geometry is actually a collection of simple (singlepart) geometries. Such a geometry is called multi-part geometry. If it contains just one type of simple geometry, we call it multi-point, multi-linestring or multi-polygon. All multi-part lines are written into the ‘Error’ field. • must not have pseudos: A line geometry’s endpoint should be connected to the endpoints of two other geometries. If the endpoint is connected to only one other geometry’s endpoint, the endpoint is called a psuedo node. On polygon layers the following rules are available: • must contain: Polygon layer must contain at least one point geometry from the second layer. • must not have duplicates: Polygons from the same layer must not have identical geometries. Whenever a polygon feature is represented twice or more it will occur in the ‘Error’ field. • must not have gaps: Adjacent polygons should not form gaps between them. Administrative boundaries could be mentioned as an example (US state polygons do not have any gaps between them...). • must not have invalid geometries: Checks whether the geometries are valid. Some of the rules that define a valid geometry are, – Polygon rings must close. – Rings that define holes should be inside rings that define exterior boundaries. – Rings may not self-intersect (they may neither touch nor cross one another). – Rings may not touch other rings, except at a point. • must not have multi-part geometries: Sometimes, a geometry is actually a collection of simple (singlepart) geometries. Such a geometry is called multi-part geometry. If it contains just one type of simple geometry, we call it multi-point, multi-linestring or multi-polygon. For example, a country consisting of multiple islands can be represented as a multi-polygon. • must not overlap: Adjacent polygons should not share common area. • must not overlap with: Adjacent polygons from one layer should not share common area with polygons from another layer.

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19.19 Plugin Statistik Zonal Plugin Statistik Zonal Anda dapat menganalisis hasil klasifikasi tematik. Hal ini memungkinkan untuk Dengan menghitung beberapa nilai-nilai piksel dari lapisan raster dengan bantuan lapisan vektor poligonal (lihat figure_zonal_statistics). Anda dapat menghitung jumlah, nilai rata-rata dan jumlah total piksel yang berada di dalam poligon. Plugin menghasilkan kolom keluaran dalam lapisan vektor dengan awalan user-defined.

Gambar 19.30: Dialog Statistik Zonal (KDE)

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Bantuan dan Dukungan

20.1 Milis QGIS masih aktif dikembangkan dan karena itu tidak akan selalu bekerja seperti yang Anda harapkan. Cara yang lebih disukai untuk mendapatkan bantuan adalah dengan bergabung di milis qgis-pengguna. Pertanyaan Anda akan menjangkau khalayak yang lebih luas dan jawabannya juga akan menguntungkan orang lain.

20.1.1 qgis-pengguna Milis ini digunakan untuk membahas QGIS secara umum, serta pertanyaan-pertanyaan spesifik mengenai instalasi dan penggunaan. Anda dapat berlangganan milis qgis-pengguna dengan mengunjungi tautan URL: http://lists.osgeo.org/mailman/listinfo/qgis-user

20.1.2 fossgis-talk-liste Untuk audien berbahasa Jerman, FOSSGIS e.V. menyediakan milis fossgis-talk-liste. Milis ini digunakan untuk diskusi GIS open source secara umum termasuk QGIS. Anda dapat berlangganan dengan mengunjungi URL: https://lists.fossgis.de/mailman/listinfo/fossgis-talk-liste

20.1.3 qgis-pengembang Jika Anda seorang pengembang menghadapi masalah yang bersifat teknis, Anda mungkin ingin bergabung dengan milis qgis-pengembang di sini: http://lists.osgeo.org/mailman/listinfo/qgis-developer

20.1.4 qgis-commit Setiap kali komit dibuat untuk kode repositori QGIS surel dikirim ke daftar ini. Jika Anda ingin mendapatkan informasi terbaru setiap perubahan basis kode saat ini, Anda bisa berlangganan di: http://lists.osgeo.org/mailman/listinfo/qgis-commit

20.1.5 qgis-trac Daftar ini memberikan notifikasi surel yang terkait dengan manajemen proyek, termasuk laporan bug, tugas, dan permintaan fitur. Anda dapat berlangganan di: http://lists.osgeo.org/mailman/listinfo/qgis-trac

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20.1.6 qgis-komunitas-tim Daftar ini berkaitan dengan topik seperti dokumentasi, konteks bantuan, panduan-pengguna, pengalaman online termasuk situs web, blog, milis, forum, dan upaya penerjemahan. Jika Anda ingin bekerja pada panduan-pengguna juga, dalam daftar ini adalah titik awal yang baik untuk mengajukan pertanyaan Anda. Anda dapat berlangganan di: http://lists.osgeo.org/mailman/listinfo/qgis-community-team

20.1.7 qgis-rilis-tim Daftar ini berkaitan dengan topik seperti proses rilis, pemaketan binari untuk berbagai OS dan mengumumkan rilis baru ke dunia pada umumnya. Anda dapat berlangganan di: http://lists.osgeo.org/mailman/listinfo/qgis-releaseteam

20.1.8 qgis-tr Daftar ini berkaitan dengan upaya penerjemahan. Jika Anda ingin bekerja pada penerjemahan panduan atau grafis antarmuka pengguna (GUI), dalam daftar ini adalah titik awal yang baik untuk mengajukan pertanyaan Anda. Anda bisa berlangganan di: http://lists.osgeo.org/mailman/listinfo/qgis-tr

20.1.9 qgis-edu Daftar ini berkaitan dengan upaya pendidikan QGIS. Jika Anda ingin bekerja pada bahan pendidikan QGIS, daftar ini adalah awal yang baik untuk mengajukan pertanyaan Anda. Anda bisa berlangganan di: http://lists.osgeo.org/mailman/listinfo/qgis-edu

20.1.10 qgis-psc Daftar ini digunakan untuk membahas isu-isu Komite Pengarah yang berkaitan dengan arah dan manajemen secara keseluruhan QGIS. Anda dapat berlangganan di: http://lists.osgeo.org/mailman/listinfo/qgis-psc Anda dipersilakan untuk berlangganan ke salah satu daftar. Harap ingat untuk berkontribusi ke dalam daftar dengan menjawab pertanyaan dan berbagi pengalaman Anda. Perhatikan bahwa qgis-commit dan qgis-trac dirancang hanya untuk pemberitahuan saja dan tidak dimaksudkan untuk mengirim surel.

20.2 IRC Kami juga mengunakan IRC - kunjungi kami dengan bergabung dalam kanal #qgis di irc.freenode.net. Butuh waktu untuk menanggapi pertanyaan Anda karena banyak orang-orang di saluran ini melakukan hal-hal lain dan mungkin diperlukan waktu beberapa saat bagi mereka untuk melihat pertanyaan Anda. Dukungan komersial untuk QGIS juga tersedia. Periksa website http://qgis.org/en/commercial-support.html untuk informasi lebih lanjut. Jika Anda melewatkan sebuah diskusi di IRC, tidak masalah! Kami log semua diskusi sehingga Anda dapat dengan mudah mengejar ketinggalan. Hanya pergi ke http://qgis.org/irclogs dan baca IRC-logs.

20.3 BugTracker Sementara milis qgis-pengguna berguna untuk jenis pertanyaan umum ‘bagaimana cara melakukan XYZ di QGIS’, Anda mungkin ingin memberitahu kami tentang bug di QGIS. Anda bisa mengirimkan laporan bug menggunakan pelacak bug QGIS di http://hub.qgis.org/projects/quantum-gis/issues. Saat membuat tiket bug baru, mohon diinformasikan alamat surel dimana kami bisa meminta informasi tambahan.

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Harap diingat bahwa bug Anda mungkin tidak selalu sesuai dengan prioritas Anda seperti harapan Anda (tergantung pada tingkat kesulitannya). Beberapa bug mungkin memerlukan upaya pengembang yang signifikan untuk memperbaiki dan tenaga kerja tidak selalu tersedia. Permintaan fitur dapat disampaikan juga menggunakan sistem tiket yang sama untuk bug. Pastikan untuk memilih jenis Feature. Jika Anda telah menemukan bug dan memperbaikinya sendiri Anda bisa mengirimkan patchnya juga. Sekali lagi, kirim ke sistem tiket redmine di http://hub.qgis.org/wiki/quantum-gis/issues. Periksa kotak centang Patch supplied dan melampirkan patch Anda sebelum mengirimkan bug. Seseorang pengembang akan meninjau dan menerapkannya ke QGIS. Harap jangan khawatir jika patch Anda tidak diterapkan langsung — pengembang terikat dengan komitmen-komitmen lainnya.

20.4 Blog Komunitas juga menjalankan weblog di http://planet.qgis.org/planet/ yang memiliki beberapa artikel menarik bagi pengguna dan pengembang juga disediakan oleh masyarakat dalam blog lain. Anda diundang berkontribusi pada blog QGIS Anda sendiri!

20.5 Plugin Situs web http://plugins.qgis.org menyediakan web resmi Portal plugin QGIS. Di sini Anda menemukan daftar semua plugin QGIS stabil dan eksperimental tersedia melalui ‘Repositori Plugin QGIS Resmi’.

20.6 Wiki Akhirnya, kami memelihara situs web WIKI di http://hub.qgis.org/projects/quantum-gis/wiki di mana Anda dapat menemukan berbagai informasi berguna yang berhubungan dengan pengembangan QGIS, rencana rilis, tautan untuk mengunduh, pesan petunjuk-terjemahan dan sebagainya. Silakan dikunjungi, ada banyak informasi bagus didalamnya!

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BAB 21

Appendix

21.1 GNU General Public License Version 2, June 1991 Copyright (C) 1989, 1991 Free Software Foundation, Inc. 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software–to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation’s software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author’s protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors’ reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone’s free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The “Program”, below, refers to 253

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any such program or work, and a “work based on the Program” means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term “modification”.) Each licensee is addressed as “you”. Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does. 1. You may copy and distribute verbatim copies of the Program’s source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. 2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions: (a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change. (b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License. (c) If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.) These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it. Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program. In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. 3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following: (a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, (b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

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(c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.) The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable. If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code. 4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it. 6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients’ exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License. 7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program. If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances. It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice. This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License. 8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License. 9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. 21.1. GNU General Public License

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Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and “any later version”, you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. 10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. QGIS Qt exception for GPL In addition, as a special exception, the QGIS Development Team gives permission to link the code of this program with the Qt library, including but not limited to the following versions (both free and commercial): Qt/Non-commerical Windows, Qt/Windows, Qt/X11, Qt/Mac, and Qt/Embedded (or with modified versions of Qt that use the same license as Qt), and distribute linked combinations including the two. You must obey the GNU General Public License in all respects for all of the code used other than Qt. If you modify this file, you may extend this exception to your version of the file, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

21.2 GNU Free Documentation License Version 1.3, 3 November 2008 Copyright 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc

Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The purpose of this License is to make a manual, textbook, or other functional and useful document “free” in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

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This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software. We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference. 1. APPLICABILITY AND DEFINITIONS This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The Document, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law. A “Modified Version” of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language. A “Secondary Section” is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document’s overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them. The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none. The “Cover Texts” are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words. A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not “Transparent” is called Opaque. Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machinegenerated HTML, PostScript or PDF produced by some word processors for output purposes only. The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work’s title, preceding the beginning of the body of the text. The “publisher” means any person or entity that distributes copies of the Document to the public. A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.)

21.2. GNU Free Documentation License

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To “Preserve the Title” of such a section when you modify the Document means that it remains a section “Entitled XYZ” according to this definition. The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License. 2. VERBATIM COPYING You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3. You may also lend copies, under the same conditions stated above, and you may publicly display copies. 3. COPYING IN QUANTITY If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects. If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages. If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using publicstandard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public. It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document. 4. MODIFICATIONS You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version: 1. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission. 2. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement. 3. State on the Title page the name of the publisher of the Modified Version, as the publisher. 4. Preserve all the copyright notices of the Document. 5. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices. 6. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.

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7. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice. 8. Include an unaltered copy of this License. 9. Preserve the section Entitled “History”, Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled “History” in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence. 10. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the “History” section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission. 11. For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein. 12. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles. 13. Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version. 14. Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section. 15. Preserve any Warranty Disclaimers. If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version’s license notice. These titles must be distinct from any other section titles. You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard. You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one. The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version. 5. COMBINING DOCUMENTS You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers. The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work. In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements”. 6. COLLECTIONS OF DOCUMENTS 21.2. GNU Free Documentation License

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You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects. You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document. 7. AGGREGATION WITH INDEPENDENT WORKS A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document. If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document’s Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate. 8. TRANSLATION Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail. If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title. 9. TERMINATION You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License. However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation. Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice. Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it. 10. FUTURE REVISIONS OF THIS LICENSE The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/. Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License “or any later version” applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a 260

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proxy can decide which future versions of this License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Document. 11. RELICENSING “Massive Multiauthor Collaboration Site” (or “MMC Site”) means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A “Massive Multiauthor Collaboration” (or “MMC”) contained in the site means any set of copyrightable works thus published on the MMC site. “CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versions of that license published by that same organization. “Incorporate” means to publish or republish a Document, in whole or in part, as part of another Document. An MMC is “eligible for relicensing” if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008. The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing. ADDENDUM: How to use this License for your documents To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page: Copyright © YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”. If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with ... Texts.” line with this: with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.

21.2. GNU Free Documentation License

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BAB 22

Literatur dan Referensi Web

GDAL-SOFTWARE-SUITE. Geospatial data abstraction library. http://www.gdal.org, 2013. GRASS-PROJECT. Geographic ressource analysis support system. http://grass.osgeo.org , 2013. NETELER, M., AND MITASOVA, H. Open source gis: A grass gis approach, 2008. OGR-SOFTWARE-SUITE. Geospatial data abstraction library. http://www.gdal.org/ogr , 2013. OPEN-GEOSPATIAL-CONSORTIUM. http://portal.opengeospatial.org, 2002.

Web

map

service

(1.1.1)

implementation

specification.

OPEN-GEOSPATIAL-CONSORTIUM. http://portal.opengeospatial.org, 2004.

Web

map

service

(1.3.0)

implementation

specification.

POSTGIS-PROJECT. Spatial support for postgresql. http://postgis.refractions.net/ , 2013.

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Bab 22. Literatur dan Referensi Web

Indeks

%%, 88 Actions, 88 Alat Analisis, 226 Alat-Alat Georeferensi, 232 anotasi, 42 apache, 129 apache2, 129 Arc/Info_ASCII_Grid, 113 Arc/Info_Binary_Grid, 113 ArcInfo_Binary_Coverage, 65 Atlas_Generation, 207 attribute table, 105 Attribute_Actions, 88 Attribute_Table, 204 Attribute_Table_Selection, 105 Avoid_Intersections_Of_Polygons, 96 baris perintah, 19 bookmark, 43 bookmark spasial lihat bookmark, 43 Browse_Maps, 61 Calculator_Field, 108 CAT, 121 Categorized_Renderer, 75 CGI, 129 Colliding_labels, 80 Color_interpolation, 117 Color_Ramp, 76 ColorBrewer, 76 Colormap, 117 Common_Gateway_Interface, 129 Compose_Maps, 189 Composer_Manager, 209 Composer_Template, 190 Contrast_enhancement, 116 Coordinate_Reference_System, 57, 124 Create_Maps, 189 Create_New_Layers, 103 crossing the 180 degrees longitude line, 70 CRS, 57, 124 CSV, 98 Current_Edits, 97

Custom_Color_Ramp, 76 Custom_CRS, 59 DB_Manager, 71 Debian_Squeeze, 129 default_CRS, 57 define an action, 88 Derived_Fields, 108 Digitizing, 96 Discrete, 117 Displacement_plugin, 78 dokumentasi, 5 editing, 93 Elements_Alignment, 206 EPSG, 57 Equal_Interval, 76 Erdas Imagine, 113 ESRI, 63 European_Petroleom_Search_Group, 57 example actions, 88 Export_as_image, 209 Export_as_PDF, 209 Export_as_SVG, 209 FastCGI, 129 Field_Calculator, 108 Field_Calculator_Functions, 109 Fitur Identifikasi, 35 Gambaran Peta, 47 GDAL, 113 GeoTIFF, 113 GeoTiff, 113 GiST (Generalized Search Tree) index, 69 GML, 121 GNU General Public License, 253 Gradient_Color_Ramp, 76 Graduated_Renderer, 76 GRASS, 139, lihat Creating new tors;editing;creating a new layer attribute linkage, 144 attribute storage, 144 category settings, 145 digitizing tools, 144 display results, 149, 150

vec-

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region, 147 region display, 147 region editing, 147 snapping tolerance, 146 symbology settings, 146 table editing, 146 toolbox, 151 GRASS toolbox, 147 Browser, 154 customize, 154 GRASS vector data model, 143 Grid Map_Grid, 195

New_Spatialite_Layer, 103 Node_Tool, 97 Nodes, 98 Non_Spatial_Attribute_Tables, 106

Histogram, 119 HTML_Frame, 205

Pan, 95 penyusun cetak cepat, 21 Peralatan Riset, 226 pgsql2shp, 68 Picture_database, 197 plugin, 211 pengelola, 211 tipe, 211 Point_Displacement_Renderer, 78 PostGIS, 66 PostGIS spatial index, 69 PostgreSQL, 66 Pretty_Breaks, 76 print_composer tools, 189 Printing Export_Map, 209 Proj.4, 59 Proj4, 58 Proj4_text, 58 Projections, 57 Proxy, 123 proxy-server, 123 proyek nesting, 44 Publish_to_Web_plugin, 129 Pyramids, 119

IGNF, 57 Import_Maps, 61 Institut_Geographique_National_de_France, 57 InteProxy, 127 jendela utama, 23 join, 91 join layer, 91 keluaran simpan sebagai gambar, 21 Konteks Bantuan, 37 kualitas rendering, 38 Layout_Maps, 189 legenda, 29 license document, 253 load a shapefile, 63 loading_raster, 113 Map_Legend, 199 Map_Navigation, 95 Map_Template, 190 MapInfo, 65 Memperbarui rendering sebelum menggambar, 38 Menghentikan rendering, 38 menghitung skala, 33 mengukur, 38 area, 39 panjang garis, 39 sudut, 39 menu, 24 merge attributes of features, 102 Merge_Attributes_of_Selected_Features, 102 Merge_Selected_Features, 102 Metadata, 119 MSSQL Spatial, 71 Multi_Band_Raster, 115 multipolygon, 101 Natural_Breaks_(Jenks), 76 New_GPX_Layer, 103, 104 New_Shapefile_Layer, 103 New_SpatiaLite_Layer, 103 266

OGC, 121 OGR, 63 OGR Simple Feature Library, 63 ogr2ogr, 68 Open_Geospatial_Consortium, 121 OpenStreetMap, 66 Oracle Spatial, 71 OSM, 66

QGIS_mapserver, 127 QGIS_Server, 129 QSpatiaLite, 71 Quantile, 76 Query_Builder, 106 Raster, 113 Raster_Calculator, 120 Renderer_Categorized, 75 Renderer_Graduated, 76 Renderer_Point_Displacement, 78 Renderer_Single_Symbol, 74 Rendering, 37 Rendering tergantung skala, 37 Rendering_Mode, 191 Rendering_Rule-based, 78 Revert_Layout_Actions, 206 ring polygons, 101 Indeks

QGIS User Guide, Rilis 2.0

Rotate_Point_symbols, 102 Rotated_North_Arrow, 197 Rule-based_Rendering, 78 Scalebar Map_Scalebar, 200 Search_Radius, 94 Secured_OGC_Authentication, 127 Select_using_Query, 107 SFS, 121 Shapefile, 63 Shared_Polygon_Boundaries, 96 Shortcut Papanketik, 36 shp2pgsql, 68 Single_Band_Raster, 115 Single_Symbol_Renderer, 74 Skala, 37 SLD, 129 SLD/SE, 129 Snapping, 94 Snapping_On_Intersections, 96 Snapping_Tolerance, 94 Spatialite, 70 Spatialite_Manager, 71 Split_Features, 102 SQLite, 70 SRS, 124 ST_Shift_Longitude, 69 Symbology, 74, 115

WMS_properties, 126 WMS_tiles, 125 WMTS, 125 WMTS_client, 121 Work_with_Attribute_Table, 104 Zoom_In Zoom_Out, 95

tata letk toolbar, 29 tetikus perbesar, 32 Three_Band_Color_Raster, 115 Tiger_Format, 65 Toggle Editing, 96 tombol mengarahkan, 32 Topological_Editing, 95 Transparency, 118 UK_National_Transfer_Format, 65 US_Census_Bureau, 65 Vertex, 98 Vertices, 98 visibilitas lapisan, 29 WCS, 121, 127 Web Coverage Service, 127 WFS, 121, 128 WFS-T, 128 WFS_Transactional, 128 WKT, 57, 98 WMS, 121 WMS-C, 125 WMS_1.3.0, 127 WMS_client, 121 WMS_identify, 126 WMS_layer_transparency, 124 WMS_metadata, 126

Indeks

267