Positional accuracy evaluation of CORS VRS, PPK, static GPS + GLONASS, and total station surveys in urban areas

Abstract

In urban environments, GNSS positioning is challenging due to signal blockage and multipath effects of surrounding buildings. This study evaluates the compatibility of CORS-VRS, PPK and static GNSS methods with total station measurements to investigate their accuracy in urban conditions. For this purpose, measurements were conducted in Esenler, Istanbul on 30 September 2020. Three measurement points (P1, P2 and P3) with varying levels of obstruction were selected. The results demonstrate that static GNSS measurements (with horizontal and vertical components below 5 mm and 11 mm, respectively) are the method with the highest positional accuracy. Conversely, PPK measurements exhibited larger deviations (0.857 m (X), 0.356 m (Y), and 0.780 m (Z) in P1, 0.302 m (X), 0.215 m (Y), and 0.255 m (Z) in P1, and 0.516 m (X), 0.284 m (Y), and 0.374 m (Z) in P3. Conversely, CORS-VRS measurements exhibited deviations ranging from 13 cm to 34 cm at baseline distances when compared to total station results. The findings demonstrate that while CORS-VRS and PPK can achieve sub-decimeter accuracy, they are significantly affected by multipath and signal blockages in dense urban environments. Thus, GNSS-based positioning in urban settings should be supplemented with total station surveys when high precision (1-2 cm) is required.