The process of delimiting a given object, either physical (e.g. a lake) or conceptual (e.g. an administrative region), in terms of its spatial relationship to the land; the geographic reference thus established consists of points, lines, areas or volumes defined in terms of some coordinate system (usually latitude and longitude, or UTM northings and eastings, and elevation). To establish the relationship between page co-ordinates on a planar map and known real-world co-ordinates, e.g. connecting an orthophoto to the ground co-ordinate system.