CONCERNS RELATED TO GPS-DERIVED GEOID DETERMINATION

The subject of accurate orthometric heights obtained from GPS observations is very attractive because GPS has the benefits of high accuracy and simultaneous 3-D positioning. Three issues - GPS-derived geoid height determination, GPS-derived geoid height densification, and GPS-derived geoid implementation - are of interest. A specific vertical test network was utilized to investigate and evaluate methods for solving these problems. The preliminary results show that the GPS approach is feasible for estimating geoid heights in a limited area; the surface interpolation methods have the capability of cm level accuracy for densifying geoid heights; and the proposed procedures have been shown to provide a satisfactory GPS-derived geoid database.