Method of forming digital models of geoid heights for reference coordinate systems

A technique was developed for generating digital models of geoid heights for reference coordinate systems using the Trimble Bussines Center software (TBC software). The source models can be the publicly available high-precision global geoid elevation models EGM2008, EIGEN6C4 and other models whose files with the *.ggf extension are compatible with the TBC software. The technique is based on the possibility of exporting orthometric heights from the TBC software in ASCII format to a user-specified area on the surface of the global WGS-84 ellipsoid for a uniform grid of nodes in lati-tude and longitude. The resulting data table is the starting point for calculating geoid heights for reference coordinate systems, which are determined by the parameters of the corresponding reference ellipsoids and Helmert parameters - spatial position, orientation and linear scale relative to the global coordinate system, according to Standard. The initial data are sufficient to calculate the digital model of the geoid heights for an arbitrary reference coordinate system. The expediency of the developed technique lies in the possibility of its use for a much more accurate calculation of the Helmert parameters for regional and other territories compared to the accepted standard values and, accordingly, a more accurate transformation of the three-dimensional positions of points between the general earth and reference coordinate systems (these issues will be discussed in a subsequent publication by the author). Approbation of the technique was carried out for several regional territories: Novosibirsk and Moscow regions, the territory of Western Siberia, the Republic of Belarus in the SK42 and SK95 coordinate systems, and the results are presented graphically in the form of geoid height maps.