4. Fitur-fitur

QGIS offers a wealth of GIS functions, provided by core features and plugins. The locator bar makes it easy to search for functions, datasets and more.

A short summary of six general categories of features and plugins is presented below, followed by first insights into the integrated Python console.

4.1. Lihat data

You can view combinations of vector and raster data (in 2D or 3D) in different formats and projections without conversion to an internal or common format. Supported formats include:

  • Spatially-enabled tables and views using PostGIS, SpatiaLite and MS SQL Spatial, Oracle Spatial, vector formats supported by the installed OGR library, including GeoPackage, ESRI Shapefile, MapInfo, SDTS, GML and many more. See section 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.

  • Mesh data (TINs and regular grids are supported). See Working with Mesh Data.

  • Data raster dan vektor GRASS dari basis data GRASS (lokasi/mapset). Lihat bagian GRASS GIS Integration.

  • Data spasial dalam jaringan sebagai Layanan OGC Web, termasuk WMS, WMTS, WCS, WFS, dan WFS-T. Lihat bagian Pekerjaan dengan Data OGC.

    The QGIS authentication infrastructure helps you manage user/password, certificates and keys for web services and other resources.

  • Spreadsheets (ODS / XLSX)

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:

  • QGIS browser

  • On-the-fly proyeksi ulang

  • Pengelola DB

  • Print layout

  • Report

  • Panel Peninjau

  • Bookmark spasial

  • Annotation tools

  • Identifikasi/pilih fitur

  • Sunting/lihat/cari atribut

  • Data-defined feature labeling

  • Alat simbologi vektor dan raster data-ditentukan

  • Peta komposisi atlas dengan lapisan graticule

  • North arrow, scale bar and copyright label for maps

  • Dukungan menyimpan dan mengembalikan proyek-proyek

4.3. Membuat, menyunting, mengelola dan ekspor data

You can create, edit, manage and export vector and raster layers in several formats. QGIS offers the following:

  • Vector digitizing tools

  • Ability to create and edit multiple file formats and GRASS vector layers

  • Plugin Georeferencer ke geocode gambar

  • GPS tools to import and export GPX format, and convert other GPS formats to GPX or down/upload directly to a GPS unit (on Linux, usb: has been added to list of GPS devices)

  • Dukungan memvisualisasikan dan mengedit data OpenStreetMap

  • Ability to create spatial database tables from files with the DB Manager plugin

  • Peningkatan penanganan tabel basis data spasial

  • Peralatan untuk mengelola tabel atribut vektor

  • Opsi menyimpan cuplikan layar sebagai gambar ber-georeferensi.

  • Alat DXF-Export dengan kemampuan ditingkatkan untuk mengekspor gaya dan plugin untuk melakukan fungsi CAD-like

4.4. Analyze data

You can perform spatial data analysis on spatial databases and other OGR-supported formats. QGIS currently offers vector analysis, raster analysis, sampling, geoprocessing, geometry and database management tools. You can also use the integrated GRASS tools, which include the complete GRASS functionality of more than 400 modules (see section GRASS GIS Integration). Or, you can work with the Processing plugin, which provides a powerful geospatial analysis framework to call native and third-party algorithms from QGIS, such as GDAL, SAGA, GRASS, R, and more (see section Pengantar). All analysis functions are run in the background, allowing you to continue your work before the processing has finished.

The graphical modeller allows you to combine / chain functions into a complete workflow in an intuitive graphical environment.

4.5. Terbitkan peta di Internet

QGIS can be used as a WMS, WMTS, WMS-C or WFS and WFS-T client, and as a WMS, WCS or WFS server (see section Pekerjaan dengan Data OGC). Additionally, you can publish your data on the Internet using a webserver with QGIS Server, UMN MapServer or GeoServer installed.

4.6. Extend QGIS functionality through plugins

QGIS can be adapted to your special needs with the extensible plugin architecture and libraries that can be used to create plugins. You can even create new applications with C++ or Python!

4.6.1. Inti Plugin

Plugin inti termasuk:

  1. DB Manager (exchange, edit and view layers and tables from/to databases; execute SQL queries)

  2. eVIS (visualize events)

  3. Geometry Checker (check geometries for errors)

  4. Georeferencer GDAL (add projection information to rasters using GDAL)

  5. GPS Tools (load and import GPS data)

  6. GRASS 7 (integrate GRASS GIS)

  7. MetaSearch Catalogue Client (interacting with metadata catalog services supporting the OGC Catalog Service for the Web (CSW) standard)

  8. Offline Editing (allow offline editing and synchronizing with databases)

  9. Processing (the spatial data processing framework for QGIS)

  10. Topology Checker (find topological errors in vector layers)

4.6.2. Plugin Eksternal Python

QGIS offers a growing number of external Python plugins that are provided by the community. These plugins reside in the official Plugins Repository and can be easily installed using the Python Plugin Installer. See Section The Plugins Dialog.

4.7. Python Console

For scripting, it is possible to take advantage of an integrated Python console, which can be opened with: Plugins ‣ Python Console. The console opens as a non-modal utility window. For interaction with the QGIS environment, there is the qgis.utils.iface variable, which is an instance of QgisInterface. This interface provides access to the map canvas, menus, toolbars and other parts of the QGIS application. You can create a script, then drag and drop it into the QGIS window and it will be executed automatically.

For further information about working with the Python console and programming QGIS plugins and applications, please refer to QGIS Python console and Pengembangan Cookbook PyQGIS.

4.8. Isu yang Diketahui

4.8.1. Jumlah dari batas berkas yang dibuka

Jika Anda membuka sebuah proyek QGIS besar dan Anda yakin bahwa semua lapisan valid, tetapi beberapa lapisan ditandai sebagai lapisan buruk, Anda mungkin dihadapkan dengan masalah ini. Linux (dan OS lain juga) memiliki batas berkas yang dibuka. Batasan sumber daya per-proses dan diturunkan. Perintah ulimit merupakan termina built-in, mengubah batas hanya untuk proses terminal saat ini; batas baru akan diturunkan oleh setiap proses anak.

You can see all current ulimit info by typing:

$ ulimit -aS

You can see the current allowed number of opened files per process with the following command on a console:

$ ulimit -Sn

To change the limits for an existing session, you may be able to use something like:

$ ulimit -Sn #number_of_allowed_open_files
$ ulimit -Sn
$ qgis

Untuk memperbaikinya selamanya

Pada kebanyakan sistem Linux, batasan sumber daya yang ditetapkan pada login dengan modul pam_limits sesuai dengan pengaturan yang terkandung dalam /etc/security/limits.conf atau /etc/security/limits.d/*.conf. Anda harus dapat mengedit berkas jika Anda memiliki hak istimewa root (juga via sudo), tetapi Anda akan perlu untuk login lagi sebelum perubahan berlaku.

Informasi tambahan:

https://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/ https://linuxaria.com/article/open-files-in-linux