INVESTIGATION OF POSITION ACCURACY IN UAVS

OpenAlex English

Digital Terrain Models (DTMs) are used as basic data in many engineering projects. In addition to classical terrestrial techniques, space and satellite techniques and Unmanned Aerial Vehicles (UAVs) are coomonly used in the production of the DTMs. In the production of the DTM with the help of the UAVs, measurements can be made easily where people can access difficultly and large areas can be mapped in a short time. However, one of the most fundamental problems in the UAVs is to obtain the most accurate DTM by choosing the homogeneously spread ground control points (GCPs) number. In this study, the effect of flight altitude and the density of GCPs on position accuracy were investigated in produce of the DTM. For this purpose, 56 points were established at approximately 40 m intervals and images from 80, 100, 120 m flight altitude were taken in the test area. The rapid static Global Navigation Satellite Systems (GNSS) method was used to obtain the coordinates of the points with high accuracy. Then, the homogeneously spread 5, 10, 15 points were chosen as GCPs, respectively. The images were evaluated in Pix4d Mapper software with 9 different combinations and DTMs were produced. Outliers of the coordinates obtained from the models were detected by Bland-Altman Plot. In order to determine the geometric accuracy of the produced models, the coordinates of the test points obtained from the models and the results of rapid static GNSS measurements were compared with the statistical methods and the obtained results were interpreted.