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A layer is a GIS data set that represents geographic features organized according to subject matter and geometry type that is overlayed with other layers through georeferencing. Layers help to organize a GIS database by grouping features by subject matter (e.g., wells, roads, soils, or elevation). Data within a GIS layer are of a consistent geometry type: that is, point, line, polygon, triangulated irregular networks (TIN), raster, and so on.

All layers in a GIS database are georeferenced, which allows them to be used in overlay operations. Georeferencing is the procedure used to bring data layers into alignment via known ground location or the procedure of bringing a map or data layers into alignment with the earth's surface via a common coordinate system. The result is ...

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