PostGIS

PostGIS turns PostgreSQL into a spatial database: it adds geometry types (points, lines and polygons in 2D and 3D), spatial indexing and hundreds of functions for measuring distances and areas, intersections, buffering and simplifying geometries, plus raster support. It connects directly to QGIS, GeoServer and MapServer, so it is often used as the central store for infrastructure data – water and sewer networks, roads, parcels and survey points – edited by several users at once. Suited to engineers, surveyors and GIS teams at municipalities and utilities. Limitations: it is not a standalone program with a graphical interface – it needs a PostgreSQL server to be installed and maintained, and working with it requires SQL skills or a GIS client that connects to it.