Comparison of the Elevations by GNSS with Thailand Geoid Model 2017 and Leveling

Abstract

Elevations above mean sea level of points are determined by GNSS method from the relationship between ellipsoidal height and geoid undulation. Geoid undulation of points is computed from TGM2017. The project area is at Khao Noi Subdistrict, Tha Muang District, Kanchanaburi Province.  Elevations of six points in the project area are first order benchmarks determined by The Royal Thai Survey Department.  Elevations of the same six points are observed by GNSS method. Comparison of elevations by both methods found that RMSE of elevations by GNSS method is equal to 0.023 meter which is better than 12mm√K (third order leveling specification). Determination of elevations by GNSS method save cost and time compared to leveling method.