The missions of constructing geodetic datums include determining and defining the coordinate system, height system, and gravity reference system, and establishing and maintaining the coordinate framework (horizontal and satellite geodetic control networks), elevation framework (vertical control network), and gravimetric framework (gravity control network). Geodesists and surveyors use datum to create starting or reference points for any work requiring accurate coordinates that are consistentwithoneanother. Again, it is geodetic datums that are referred to when the spatial positions of geographical features in the real world are expressed in the data space.
#Geodetic datum series
The coordination of geographical data is done by a series of triangulations using the GCPs.
Geodetic datums provide initial data for all kinds of surveying and mapping work and serve as the foundation for determining the geometric shape and spatial–temporal distribution of geospatial information. The geodetic datum for the Indian region is defined (through actual physical measurements) with respect to the mathematically defined ellipsoidal surface (by specifying the semi-major axis and flatness) called the Everest Spheroid (first defined in 1830). Geodetic datums consist chiefly of coordinate datums (including classical horizontal datums and three-dimensional coordinate datums), vertical datums, sounding datums, as well as gravity datums. To measure terrain, surface features, position coordinates, heights, and gravity values at points on the Earth’s surface, there need to be corresponding reference points or surfaces (also known as datum points or surfaces), namely geodetic datums, to which surveying and mapping results are referred.