Overlap influence in images obtained by an unmanned aerial vehicle on a digital terrain model of altimetric precision

Abstract

Photogrammetric data are systematically used in several segments. Products such as Digital Terrain Models (DTMs) provide detailed surface information, however the geometric reliability of these products is questionable compared to data collected by topographic survey by GNSS RTK. The present research assesses the quality of DTMs obtained using an Unmanned Aerial Vehicle (UAV) with different parameters, overlap percentages, and flight directions, comparing the results to those of the topography method Global Navigation Satellite System – Real-Time Kinematic (GNSS RTK). Were done twelve flight plans with different overlaps (90x90, 80x80, 80x60, 70x50, 70x30, and 60x40%) and directions (transverse and longitudinal to the planting line). The parameters of height (Above Ground Land- AGL) and speed were fixed at 90 m and 3 m/s respectively and a Ground Sample Distance (GSD) of 0,1 m is obtained for all flights. Overall, the flight with 70x50% overlap in the transverse direction generated the best results, with a total processing time of 12 minutes and 17 seconds (about 1.5 hours faster than 90x90%), an Root Mean Square Error (RMSE) 0.589 m, and meets the minimum overlap required by 60X30% aerophotogrammetry; furthermore, the results did not differ statistically from the high overlaps of 90x90% and 80x80%.