1 [surveying] An accurately surveyed coordinate location for a physical feature that can be identified on the ground. Control points are used in least-squares adjustments as the basis for improving the spatial accuracy of all other points to which they are connected.
2 [coordinate systems] One of various locations on a paper or digital map that has known coordinates and is used to transform another datasetspatially coincident but in a different coordinate systeminto the coordinate system of the control point. Control points are used in digitizing data from paper maps, in georeferencing both raster and vector data, and in performing spatial adjustment operations such as rubber sheeting.