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주요 기능

QGIS 에는 핵심기능과 플러그인에 의해 제공되는 여러가지 GIS 공통기능이 존재합니다. 기능과 플러그인에 대한 여섯 가지 구분에 대한 짧은 설명이 아래에 있으며, 파이썬 콘솔 통합으로의 첫번째 소개가 뒤따릅니다.

데이터 보기

내부포맷이나 공통포맷으로 변환하지 않더라도 다양한 포맷/투영의 벡터/래스터 데이터를 확인하고 중첩할 수 있습니다. 지원되는 포맷은 다음과 같습니다:

  • PostGIS, SpatiaLite 및 MS SQL Spatial, Oracle Spatial을 이용한 공간 테이블과 뷰, 설치된 OGR 라이브러리가 지원하는 ESRI 쉐입, MapInfo, SDTS, GML 및 기타 많은 벡터 포맷. 다음 섹션 참조 벡터 데이터로 작업하기.

  • GeoTIFF, ERDAS IMG., ArcInfo ASCII GRID, JPEG, PNG 등, 설치된 GDAL (Geospatial Data Abstraction Library) 라이브러리가 지원하는 래스터 및 이미지 포맷. 다음 섹션 참조 래스터 데이터로 작업하기.

  • GRASS 데이터베이스(location/mapset)에 포함된 GRASS 래스터 및 벡터 데이터. 다음 섹션 참조 GRASS GIS Integration.

  • WMS, WMTS, WCS, WFS, WFS-T를 포함하는 OGS 웹 서비스에 의해 제공되는 온라인 공간 데이터. 다음 섹션 참조 OGC 데이터로 작업하기.

데이터 탐색 및 지도 제작

사용자는 지도를 만들 수 있으며 공간 데이터를 친숙한 GUI를 통해 탐색할 수 있습니다. GUI에는 많는 도움이 되는 다음과 같은 툴들이 있습니다:

  • QGIS 탐색기

  • 실시간 투영변환

  • DB 관리자

  • 지도 조판기

  • 오버뷰 패널

  • 지리적 북마크

  • 주석 도구

  • 객체 선택/정보보기

  • 속성 편집/보기/검색

  • 데이터에 의해 정의되는 피처 라벨

  • 데이터에 의해 정의되는 벡터 및 래스터 심볼 툴

  • Atlas map composition with graticule layers
  • North arrow scale bar and copyright label for maps
  • Support for saving and restoring projects

데이터 생성, 편집, 관리 및 내보내기

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

  • Digitizing tools for OGR-supported formats and GRASS vector layers
  • Ability to create and edit shapefiles and GRASS vector layers
  • Georeferencer plugin to geocode images
  • 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.)
  • Support for visualizing and editing OpenStreetMap data
  • Ability to create spatial database tables from shapefiles with DB Manager plugin
  • 진보된 공간 데이터 테이블 다루기

  • Tools for managing vector attribute tables
  • Option to save screenshots as georeferenced images

데이터 분석

You can perform spatial data analysis on spatial databases and other OGR- supported formats. QGIS currently offers vector 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, fTools and more. (See section Introduction.)

인터넷에 지도 발행하기

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 OGC 데이터로 작업하기.) Additionally, you can publish your data on the Internet using a webserver with UMN MapServer or GeoServer installed.

플러그인을 이용한 |qg|의 기능 확장

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!

핵심 플러그인

Core plugins include:

  1. Coordinate Capture (Capture mouse coordinates in different CRSs)
  2. DB 관리자 (레이어와 테이블 교환, 편집 및 보기; SQL 쿼리 실행)

  3. Diagram Overlay (Place diagrams on vector layers)
  4. Dxf2Shp Converter (Convert DXF files to shapefiles)
  5. eVIS (Visualize events)
  6. fTools (Analyze and manage vector data)
  7. GDAL 툴 (|qg|에 통합된 GDAL 툴)

  8. Georeferencer GDAL (Add projection information to rasters using GDAL)
  9. GPS Tools (Load and import GPS data)
  10. GRASS (Integrate GRASS GIS)
  11. Heatmap (Generate raster heatmaps from point data)
  12. Interpolation Plugin (Interpolate based on vertices of a vector layer)
  13. Offline Editing (Allow offline editing and synchronizing with databases)
  14. 오라클 스패셜 GeoRaster

  15. 처리(과거 SEXTANTE)

  16. Raster Terrain Analysis (Analyze raster-based terrain)
  17. Road Graph Plugin (Analyze a shortest-path network)
  18. 공간 조회 플러그인

  19. SPIT (Import shapefiles to PostgreSQL/PostGIS)
  20. SQL Anywhere 플러그인 (SQL Anywhere 데이터베이스에 벡터 레이어 넣기)

  21. Topology Checker (Find topological errors in vector layers)
  22. Zonal Statistics Plugin (Calculate count, sum, and mean of a raster for each polygon of a vector layer)

외부 파이썬 플러그인

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.

파이썬 콘솔

For scripting, it is possible to take advantage of an integrated Python console, which can be opened from menu: 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 QgsInterface. This interface allows access to the map canvas, menus, toolbars and other parts of the QGIS application.

For further information about working with the Python console and programming QGIS plugins and applications, please refer to http://www.qgis.org/html/en/docs/pyqgis_developer_cookbook/index.html.

Known Issues

Number of open files limitation

If you are opening a large QGIS project and you are sure that all layers are valid, but some layers are flagged as bad, you are probably faced with this issue. Linux (and other OSs, likewise) has a limit of opened files by process. Resource limits are per-process and inherited. The ulimit command, which is a shell built-in, changes the limits only for the current shell process; the new limit will be inherited by any child processes.

You can see all current ulimit info by typing

[email protected]:~$ ulimit -aS

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

[email protected]:~$ ulimit -Sn

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

[email protected]:~$ ulimit -Sn #number_of_allowed_open_files
[email protected]:~$ ulimit -Sn
[email protected]:~$ qgis

To fix it forever

On most Linux systems, resource limits are set on login by the pam_limits module according to the settings contained in /etc/security/limits.conf or /etc/security/limits.d/*.conf. You should be able to edit those files if you have root privilege (also via sudo), but you will need to log in again before any changes take effect.

More info:

http://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/ http://linuxaria.com/article/open-files-in-linux?lang=en