Establishing geoid model from GNSS static and kinematic method using polynomial interpolation from variable buffer size on orthometric height co-station

Abstract

Abstract

In modern survey, besides using rod leveling method to obtain orthometric height, the widely known method of using geoid undulation equation from geoid model and ellipsoidal height obtaining from GNSS. However, by using this method, there is a significant error from geoid model interpolation and error from measuring elevation by GNSS which is 2-3 times greater than horizontal error. Even though using the latest TGM2017 and hybrid geoid model in Bangkok and vicinity area, the minimum distance satisfying the 3^rd order of leveling standard, 12mm , is still greater than 5 kilometers. Moreover, increasing distance to meet the criteria is increasing range of acceptable error and noise data as well which is not the solution because the increased noise affects confidence level of data in practical use.

In this study, the main objective is to establish the best fit geoid model in any specific area to eliminate significant error from geoid undulation model interpolation to satisfy the leveling criteria and to obtain greater vertical accuracy by using variable buffer size and polynomial interpolation method.

Keywords : Geoid Model, Orthometric Height, GNSS, Polynomial Interpolation