The Effeect of DTM Resolution in Topographical Corrections on Gravity

The one gravity equipotential surface of particular interest is that which best approximates the ( mean) sea level over the whole earth. It is called geoid ( Vanicek & Krakiwsky, 1986) . It is most natural repesentation of the earth shape thus the knowledge of the geoid is important in geodesy. It has very importmant role for determination of orthometric heights from obtained heights by GPS, i.e., ellipsoidal heights. The use of Stokes is fromula in gravimetric geoid determination requires that the gravity anomalies represent boundary values on the geoid, this means that the measured gravity ( usully taken on the Earth surface) must be reduced to the geoid and there mist be no masses outside the geoid(Heiskanen and Moritz, 1967).