Quantum GIS
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Qualitative Spatial Representations Geosensor Networks, Qualitative Monitoring of
Dynamic Fields
Quality of Information Computing Fitness of Use of Geospatial Datasets
Quality of Services Network GIS Performance
Quality, Spatial Data Imprecision and Spatial Uncertainty
Quantization
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QGIS provides a plugin mechanism which can be used to add support for a new data source or to extend the functionality of the main program in a modular way. Figure 1 shows a screenshot of the QGIS program with the map window, the legend and the attribute table opened.
Historical Background The QGIS project was founded by Gary Sherman in 2002. He was looking for a fast geographic data viewer that runs on Linux and supports a broad range of data sources. However at this time, most commercial software vendors in the GIS domain sold their desktop products only for one operating system. Therefore, he decided to start a new software project. In June 2002, QGIS was officialy registered as a project on the SourceForge webpage. The first CVS checkin dates were from July 6th 2002. The QGIS project continuously attracted more software developers and users. Today (December 2006), QGIS consists of approximately 94000 lines of code and is used by thousands of people all around the world.
Indexing, High Dimensional
Scientific Fundamentals
Quantum GIS M ARCO H UGENTOBLER Institute of Cartography, ETH Zurich, Zurich, Switzerland Synonyms QGIS; Open Source; Qt libray; MapServer Definition Quantum GIS [1] is an opensource GIS written in C++ available under the conditions of the GPL license. It is based on the C++ crossplattform library Qt from Trolltech [4]. Therefore, it runs on most existing operating systems, including Linux, Unix, Mac OS X and Windows. The name ‘Quantum GIS’ has no special meaning, except that it starts with a Q, indicating that it uses the Qt library. The main focus of QGIS is interactive two dimensional viewing of spatial data. However, there is also functionality for editing vector data and a GRASS plugin to use the analytical functionality of the GRASS program [3] from within the QGIS GUI. QGIS supports a large number of vector and raster formats, including PostGIS, GRASS, Shapefile, GML, WFS, GPX, WMS, GeoTiff, PNG, JPG and many others. QGIS supports reprojecting on-the-fly for vector data sets by using the PROJ4 library.
Features In order to have an idea of the functionality provided by QGIS, the main features are summarized below. Please keep in mind that the number of features constantly increases. • Map navigation The usual set of zoom-, pan-, and info tools are available. Additionally, QGIS provides an overview window to facilitate navigation in the map. To store view extents, QGIS has the mechanism of spatial bookmarks. • Attribute table For vector layers, the thematic attributes can be viewed in a table. Besides showing attribute values, the table contains the functionalities of sorting rows, selecting features, editing values and searching features by attribute values. • Vector symbolisation The o
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