Adjustment of Orthometric Height by Least Squares Method using GNSS Leveling Equations from Multi-baseline

Correction of Orthometric Height by Least Squares Method using GNSS Leveling Equations from Multi-baseline

Abstract

Orthometric height is the height referenced from the mean sea level, which is the height used in various engineering works. Currently, Global Navigation Satellite System (GNSS) can provide the orthometric height making this method more convenient and resource-saving in operation. However, this method still has limitations regarding the appropriate baseline distance. This research aims to evaluate the efficiency of GNSS leveling utilizing three baselines approaches with CORS along with geoid height obtained from Thai geoid model (TGM2017). In addition, GNSS-derived orthometric height obtained from single baseline is compared. The results of two mentioned approaches are then compared with the orthometric height from the first-order benchmarks. The study found that in the case of a long baseline, the method of adjustment of three baselines can provide lower error than single baseline processing with RMSE of 0.035 meters, which is a reduction of approximately 37%.