Comparison of local geoid height surfaces, in the province of Trabzon

In this study, the estimation of a local geoid model in the area of Trabzon by using geometric methods is presented. The geometric method used in this study interpolates Global Positioning System-derived ellipsoidal and orthometric heights by using the weighted average interpolation, polynomial surface regression, and multiquadratic interpolation. The orthometric and ellipsoidal heights measured at 600 C3 order control stations within a reference benchmark network covering the entire area of Trabzon in Turkey were used in this study. From the existing orthometric and ellipsoidal heights at control stations, the geoid heights were determined. Control stations were divided into two sets, namely, “reference stations” and “testing stations,” to test the estimated geoid height surface. The three methods are compared from a practical point of view by using the descriptive statistics of the root mean square error, mean absolute error, maximum error, and minimum error of the geoid height residuals.