geographic information system

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A geographic information systems or GIS organises and visualises geograohic data. The data may concern particular locations, and often data is encoded this way, but more generally features have extent, so better systems also allow, regions (e.g. a country or lake) or paths (e.g a river or road). In some case, for example geological data, elevation (or depth) may be important leaidng to what is effecuevly 3D data. Special data structures may be required to manaye queries about locations, including as quadtrees for 2D locations or octrees for 3D positions.

Used on Chap. 12: page 263

Also known as graphical information systems