Real-Time Determination of Orthometric Heights Accurate to the Centimeter Level Using a Single GPS Receiver: Case Study

Abstract

Real-time determination of orthometric heights at cm level accuracy can be achieved in Dubai, U.A.E., using a single geodetic-grade global positioning satellite (GPS) receiver. This process requires that the rover receiver uses on-line measurement corrections from multiple reference stations real-time kinematic (RTK) networks, and geoid heights from a precise gravimetric geoid model. The Dubai RTK network consists of five active reference stations and can provide ellipsoidal heights with external accuracy less than 4 cm and a precision of 3 cm. The Dubai geoid model was recently developed integrating a comprehensive set of gravity, GPS, leveling, and digital elevation data to fit GPS/leveling at the 3–5 cm level RMS. To evaluate this technique, a field test on 41 benchmarks of the Dubai second-order leveling network was performed. In this test, orthometric heights derived from the presented method using a single GPS receiver were compared to their precise values determined by spirit leveling. The height differences were analyzed and statistically examined. Results show that orthometric heights determined from the GPS RTK network and geoid data can be accurate to 2–5 cm with no significant systematic errors. The method can thus be considered a good alternative to traditional leveling, particularly for third-order leveling in large areas.