Geodetic Datum

A geodetic datum is a set of parameters that defines the origin, orientation, scale, and reference surface of a coordinate system used to describe positions on or near the Earth. It establishes how a coordinate reference system is physically realized and linked to the Earth’s figure and gravity field. Datums can be local, regional, or global, and may be based on a reference ellipsoid and a defined reference frame.

In geodesy, the geodetic datum is fundamental for ensuring consistent positioning, mapping, navigation, and geospatial data integration. Modern global datums are realized through space-geodetic techniques such as GNSS, VLBI, SLR, and DORIS, forming the basis of terrestrial reference frames like the ITRF. Accurate datum definition and transformation are essential for combining observations across time, regions, and measurement techniques.