As known, three dimensional position (3D) of a point on the earth can be obtained by GPS. It has emerged that ellipsoidal height of a point positioning by GPS as 3D position, is vertical distance measured along the plumb line between WGS84 ellipsoid and a point on the Earth’s surface, when alone vertical position of a point is examined. If orthometric height belonging to this point is known, the geoid undulation may be practically found by height difference between ellipsoidal and orthometric height. In other words, the geoid may be determined by using GPS/Levelling measurements. It has known that the classical geodetic networks (triangulation or trilateration networks) established by terrestrial methods are insufficient to contemporary req...