Mathematical Models within Geodetic Frame

The geodetic frame is defined from the practitioner's point of view, i.e., the deflection of the vertical and the geoid undulation must be available for the reduction of observations. The three‐dimensional, the two‐dimensional ellipsoid, and the conformal mapping model are identified as the prime mathematical models to be used for the analysis of surveying data. It is pointed out that the three‐dimensional model is the most natural one and allows the incorporation of vector observations as derived from modern satellite surveying techniques. Whereas conformal mapping of the ellipsoidal surface may be very suitable for purposes of pictorial display, the ellipsoidal and the conformal model are quite complicated mathematically because the geodesic is required. A minimum requirement for a software package on the three‐dimensional model is described.