Wikipedia:Graphics Lab/Resources/QGIS/Get ready: Difference between revisions
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[[File:Washington_topographic_map-fr.svg|300px|thumb|Map with imported GIS data: topographic background, shaded relief, administrative borders, and [[OpenStreetMap]] roads. The labels, icons, and legend are easily added later using [[Inkscape]].]]
'''QGis''' (full name: '''[[Quantum GIS]]''') is a [[GPL license]], cross-platform ([[Windows]], [[Linux]], [[Mac OS|Mac]]), and rather friendly cartographic software application. It is a [[Geographic information system|Geographic Information System]] (GIS) program you can use to create, view, and analyze maps. In a nutshell, a GIS associates with each geographic coordinate (dot) on Earth a specific value from some survey. The best example of this is altitude: a [[topographic map]], like the ones you see on the right, can be created from a GIS file in which each pixel also carries not only a geographic coordinate, but also information about its altitude. Reversely, objects can be placed on a map and associated with specific coordinates; this is commonly used for features such as roads, lakes, state or province borders, urban areas, etc. As a result, these features are [[wikt:georeferenced|georeferenced]] on separate layers and their shape and ___location match their actual appearance on the surface of the Earth.
This approach radically changes the process of making maps. Formerly, the mapmaker or graphist had to personally draw each layer of a map, then combine them into an image. The work's reliability and precision were limited by the user's resources and knowledge. Now, the mapmaker can collect precise GIS data from reliable sources and simply load them into QGis. Objects will be automatically placed in their exact coordinates, allowing the user to apply custom styles and output an accurate basemap, which may be the end product, or a background to host additional custom layers (icons, labels, a legend, etc.). For Wikipedia, the advantages of GIS maps are precision, reliability, consistency, and an upgrade in visual elegance of the final images. Using QGis will be mainly helpful in generating '''topographic backgrounds (png, svg), shaded reliefs (png), and administrative regions or borders (png, svg)''', and applying various styles to them.
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