Digital Terrain Models Generated with Low-Cost UAV Photogrammetry: Methodology and Accuracy

Digital terrain model (DTM) generation is essential to recreating morphology once the external elements are removed. Traditional survey methods still used collect accurate geographic data on land surface. Given emergence of unmanned aerial vehicles (UAVs) equipped with low-cost digital cameras and better photogrammetric for mapping, efficient approaches necessary allow rapid surveys high accuracy. This paper provides a review, complemented authors’ experience, regarding UAV process field parameters DTM using popular commercial software images obtained fixed-wing or multicopter UAVs. We analyzed quality accuracy DTMs based four categories: (i) system (UAV platforms camera); (ii) flight planning image acquisition (flight altitude, overlap, speed, orientation line, camera configuration, georeferencing); (iii) (software, alignment, dense point cloud generation, ground filtering); (iv) geomorphology use/cover. For flat terrain, photogrammetry provided horizontal root mean square error (RMSE) between 1 3 × sample distance (GSD) vertical RMSE 4.5 GSD, and, complex topography, 7 GSD 1.5 5 GSD. Finally, we stress that can provide when variables optimized.