Unmanned aerial vehicles (UAVs) have become a prevalent tool for large-scale mapping, offering efficient and cost-effective solutions. This study examines the position accuracy of photogrammetric outcomes generated from UAV imagery when ground control point (GCP) coordinates are derived using Precise Point Positioning with Ambiguity Resolution (PPP-AR). Utilizing a Parrot ANAFI UAV, 10-minute GNSS measurements at six GCPs were processed with open-source PPP-AR software, including Pride PPP-AR, PPP-Arisen, and raPPPid. To evaluate the impact of session durations, the 10-minute data were divided into 7- and 5-minute intervals. Accuracy analysis was conducted by comparing the coordinates and distance differences of six pillars, determined through static GNSS sessions, with those derived from photogrammetric models. Results indicate that photogrammetric outcomes based on 10-minute GNSS observations provide optimal position accuracy, particularly in flat terrains, meeting practical mapping requirements but proving insufficient for high-precision geodetic applications. The study found that 5- and 7-minute observations produced greater errors, especially with raPPPid software. However, all solutions achieved sub-meter accuracy levels, with no statistically significant differences in accuracy between the tested software for 10-minute durations. These findings highlight the importance of session duration and terrain characteristics in achieving accurate photogrammetric outcomes.