Investigation of the effects of different flight parameters on the accuracy of dem generated using UAV systems

The use of Unmanned Aerial Vehicles (UAV) is an effective and inexpensive approach for data collection in addition to facilitating the production of high spatial resolution image-based products. Software based on Structure-from Motion (SfM) algorithm has been used for a long time to obtain 3 dimension (3D) models from overlay images obtained using these systems. In this study, it is aimed to investigate the effects of different flight parameters on the accuracy of orthomosaic, Digital Elevation Model (DEM) and point clouds produced with UAV Systems. In addition, the impact of rolling shutter effect and automatic and pre-calibrated camera calibration parameters on photogrammetric products such as point cloud and DEM was investigated. Within this context, a total of seven UAV flights with different heights, overlapping ratio, flight angles and single/double grid were carried out at an open-mine area located within the borders of Aksaray province. Agisoft MetaShape and Pix4D Mapper, that are widely used commercial software today, were used to evaluate the obtained UAV images. The 3D coordinates of 27 GCPs established within the scope of the study were measured twice at one hour intervals using the Global Navigation Satellite Systems (GNSS) technique, and 15 of these points were used as reference points and the remaining 12 as control points. In order to test the geometric accuracy of the point cloud, 1300 detail points were measured in the study area with the Network-RTK method. CloudCompare and ArcGIS software were used to test the geometric accuracy of the photogrammetric products obtained as a result of the evaluation.