3D Mapping Database Aided GNSS RTK and Its Assessments in Urban Canyons

Different revolutionary applications, like the unmanned autonomous systems, require a highly precise positioning with centimetre-level accuracies. And real-time kinematic (RTK) GNSS positioning stands a chance to these potential applications. RTK positioning can provide a centimetre-level positioning in open-sky or suburban environments. However, the performance is limited in a deep urban canyon with severe multipath and cycle slip effects. The measurements with noise will introduce error and results in bad solution quality. Therefore, removal on the bad measurements and remain those good-condition signals become essential for performing RTK in the urban environment. Based on this idea, this article proposes using 3D building model with position hypothesis to select the healthy satellites for RTK positioning. We believed that using the 3D building model can better exclude the unhealthy or nonline-of-sight satellite compared to using a fixed high elevation angle mask. Therefore, this article will compare the position results between 3D mapping-aided GNSS RTK and the GNSS RTK with a fixed elevation angle mask. Geodetic- and commercial-grade receivers are employed to perform experiments in the urban environment of Hong Kong. The experiment results with geodetic-grade receiver showing that 3DMA GNSS RTK can provide a positioning accuracy with 10 cm averagely.