Comparison of Digital Elevation Models Produced with Photogrammetric Usage of UAV by Geodetic Techniques

Unmanned Aerial Vehicles (UAV) use in the production of the map for photogrammetric purposes. Unlike aerial photogrammetry, UAV cameras are non-metric amateur cameras. Therefore, they need some operations to use in photogrammetry. Structure from Motion (SfM) algorithms prefers for processing images because of the usage of the non-metric cameras. These algorithms generally identify key-points (via feature extraction) on the photos and match tie-points (via feature point matching) in overlap images. SfM is a photogrammetric technique that produces keypoint to match by identifying key points, such as edge-to-corner points, through high-resolution RGB photos. The scope of this study was to compare the results obtained by UAVs and the results acquired by ground truth data. In this comparison, SfM algorithm performance, the effects of flight height, overlap rate, and UAV-type on the model investigated, and significant results achieved. Additionally, the models obtained from the UAV photographs with different flight heights and overlaps in the areas with varying characteristics of the slope compared. Consequently, it determined the difference between around 20 cm (Z value), comparing the flight height of 80 m and the flight height of 120 m. Since it is observed that the flight height does not have a significant effect.