Advances in UAV Operations for Valley-Type Mapping with Different Duration Period PPP-AR Methods in GCP

Abstract

This study evaluates the performance of the Precise Point Positioning with Ambiguity Resolution (PPP-AR) method under varying durations and software platforms in determining the optimal placement of Ground Control Points (GCPs) for use in photogrammetric products generated by Unmanned Aerial Vehicles (UAVs) over valley-type rugged terrain. In the field experiment, six GCPs and twenty checkpoints were established, and GNSS measurements with 5-s intervals were collected for 2 h at the GCPs. The collected GNSS data were segmented into 3-min and 10-min intervals, and PPP-AR-based solutions were generated for the complete datasets as well as for the 3- and 10-min subsets. The software tools used for PPP-AR processing included CSRS-PPP, Pride PPP-AR, PPP Arisen, and raPPPid. Eleven photogrammetric models were constructed using the coordinates obtained, and their accuracies were assessed using the checkpoints. The results indicate that, in terms of horizontal accuracy, the best performance was achieved using CSRS-PPP and Pride PPP-AR with 10-min observation durations. The static GNSS method yielded the most precise results for vertical accuracy, while among PPP-AR solutions the 10-min CSRS-PPP application demonstrated superior performance. Additionally, models were generated using only three GCPs placed according to different strategies, revealing that satisfactory levels of accuracy can be achieved when GCPs are strategically positioned. This study demonstrates that the PPP-AR method can be reliably utilized for high-accuracy GCP acquisition within short durations, even in challenging terrain conditions.