3D Geometric Assessment of a Commercial RTK/PPP Visual Positioning Mobile Sensor

Abstract. The Leica GS18i visual positioning system, introduced in 2021, uses 3D imaging to measure points beyond the reach of conventional GNSS receivers, such as building façades. By leveraging RTK and PPP GNSS capabilities, it enables continuous image acquisition during surveys. This study assessed its 3D geometric accuracy in both open and complex environments with poor GNSS signals. Two field tests at Vindolanda Roman Fort and Newcastle University’s Quadrangle Gateway served to evaluate processing results within the proprietary Leica Infinity and Agisoft Metashape. Results demonstrated 3D RMSEs of ca 3.5 cm in RTK mode without GCPs and 2.5 cm when all images are triangulated with a single GCP. The system achieved consistent cm-level accuracy and precision under challenging conditions with sufficient initial GNSS RTK image orientation. Comparative analyses with Canon DSLR datasets highlighted the GS18i system’s efficiency, though software differences emerged.