Determination of Orthometric Height using GNSS and EGM Data: a Scenario of the Federal University of Technology Akure

The advent of Global Navigation Satellite System (GNSS) and Earth Gravitational Model (EGM)particularly Positioning (GPS) has modernized geodetic surveying in providing horizontal vertical positions points with a sub-meter level accuracy over the reference ellipsoid. GPS gives ellipsoidal heights which makes conversion to orthometric possible by incorporating geoid model. conventional method determining height is tedious, time-consuming, labour intensive. This study entails determination using GNSS EGM data. A total forty-nine (49) stations selected within area were occupied for observation South DGPS instrument static mode position determination. geoidal values derived data computed GeoidEval utility software three different EGMs (EGM2008, EGM96 EGM84). In order determine stations, difference between (NEGM) computed. results show that obtained respect EGM2008 better standard deviation 9.530m error 1.361m. reveals use less expensive, accurate time-saving compared approach spirit levelling.