The story of Quantum GIS (QGIS) begins in 2002 under the leadership of Gary Sherman who wanted to have a GIS viewer on Linux .At its origin, it was intended to be a GRASS data visualization tool . Nowadays , this project is supported by OSGEO and has, considerably, evolved and offers features close to commercial GIS while being usable on most platforms (Windows, Mac, Linux
…). This
GIS has developed very many features . Quantum GIS has the particularity to pursue a parallel development with GRASS using of its graphic features.
Installation
The installation is simple, it is performed in a classic way, downloading the Quantum website.
Access to data
Although originally designed as a simple viewer for PostGis , QGIS relies on the GDAL-OGR library to, considerably, develop the list of accessible data formats for reading and / or writing .
QGis works with both types of GIS data main features: data vector ( representation of geographical entities such as point, line, area …) and
raster data (representative of a territory in the form of pixels, as an aerial photo , a digital terrain model, etc …).
At vectors level this listing accounts for nearly thirty formats including: ESRI shapefile, FMEObjects Gateway, File MapInfo, Oracle
Spatial, PostgreSQL, SQLite, WFS …
At raster level the list is much longer since it counts with more than fifty formats including : Arc / Info ASCII Grid,
ECW, TIFF, GeoTIFF,
OGC WCS and
WMS, USGS SDTS DEM …
QGIS is the only one that allows access in native form (without transformation
of the format) to so many data sources . When using QGIS, this flexibility is really handy since it is no longer necessary to convert data format before you can check them.
This flexibility is, also, found when exporting data. It is, as well, possible to convert these later by, simply, using the option “Save as …”
Features
The available QGis featuress can be divided in two categories :
features available in the software core
features available by adding ” plugins ”
Among the first type, all the basic functions of a desktop GIS: creation and modification of data, data representation,
composition and printing cards, … are included.
The second type allows the realization of evolved features, and, also, the integration of very powerful data and services: display of google maps as base map, georeferencing , images tessellate
and cutting , etc.
