An investigation on effects of flight altitude, forward and inside overlaps on calibration parameters in UAV images

Abstract. Accurate 3D models obtained through the combined use of photogrammetry and unmanned aerial vehicles (UAVs) have become highly valuable in various industries. These models offer a wealth of information and serve as effective tools for diverse applications. UAV photogrammetry technology provides a cost-efficient and productive solution for generating precise 3D models. Flight altitude and forward and side overlaps are critical factors influencing the production of these models, as they directly impact calibration parameters and overall accuracy. In this study, we conducted experiments using a DJI Phantom 4 Pro UAV at flight altitudes of 60 m, 90 m, and 120 m, with forward and side overlaps set at 60%, 70%, and 80%. By analyzing the residual errors of 3D sparse points generated from tie points, a significant finding emerged. The combination of a 90 m flight altitude and a 60% forward and side overlap yielded the most favorable results in terms of residuals, with a value of 0.1954 pixels and an estimated focal length of 8.7999 mm. These findings highlight the optimized accuracy and precision achieved by this particular combination in generating 3D models.