Abstract

We can obtain the position of any point on earth easily, accurately and quickly as geocentric coordinates (X, Y, Z) or geodetic coordinates (Ø, λ, h) in the World Geodetic System (WGS84) coordinate system with global positioning system (GPS) technique widely used in engineering studies today. However, we need to convert the ellipsoid height (h) to orthometric height to be able to use it in the applications. In this study, radial basis functions (RBF) and modified quadratic shepard (MQS) interpolation methods were used to determine orthometric heights from GPS measurements in two different study fields. It has been observed that multiquadric interpolation method gave better results when statistical values of test points in the study fields were considered.

Key words: Global positioning system (GPS) /leveling, geoid height, interpolation.