RESEARCH OF GPS HEIGHTING WITH NETWORK RTK MEASUREMENTS

Abstract

Different from the traditional levelling, the modernized height survey is an economical technology. It can obtain orthometric heights through the geoid undulation and the ellipsoidal heights from GPS observations, which is called “GPS-heighting” or “GPS-levelling”. GPS-heighting mostly uses static measurements to obtain the position and ellipsoid height information. However, the Virtual Base Station - Real Time Kinematic (VBS-RTK) is more efficient than static GPS surveying. Taiwan has built up a regional network RTK system, called e-Global Navigation Satellite System (e-GNSS), which provide the real-time kinematic positioning based VBS-RTK and network Differential GNSS (DGNSS). Considering a more efficient procedure on GPS-leveling, we obtain the measurements at benchmarks by using e-GNSS instead of GPS in this paper. The geoid undulation is estimated by using gravimetric and hybrid geoid model respectively. In addition to geoid models, we verify the accuracy of e-GNSS levelling by difference method. With the high efficiency, accuracy and low costs, the GPS-heighting based on network RTK can be applied more widely on engineering and disaster prevention and rescue.