Assessing the geometric accuracy of UAV-based orthophotos

Attempt has been made in this research to investigate geometric quality of an Unmanned Aerial Photograph from Trimble UX5 Aerial imaging solution for map generation and compilation despite the limited number of control points used and the mode of establishment of the control points. Two important criteria are pivotal to Geometric quality assessment of an Aerial photograph; Geometric accuracy and Object-definition property but this research bothers on the geometric accuracy. In remote sensing and photogrammetric operations, the geometric quality of the imagery basically depends on the relation between pixel size and the map scale, contrast information, atmosphere and the sun elevation, the printing technology, screen resolution and the visual acuity. The Unmanned Aircraft System (UAS) deliverables which are the orthophoto and the digital surface model (DSM) show that UAS (Trimble UX5) can be used for compilation of large scale maps in partly accessible or inaccessible areas according to the map accuracy analysis of the National Standard for Spatial Data Accuracy (NSSDA, 1998). The horizontal accuracy of 3.207m (RMSE: 1.85m) and vertical accuracy of 0.884m (RMSE: 0.45m) were obtained which fall within the allowable misclosure, hence, suitable for Cadastral map compilation.Keywords: Geometric Accuracy, Object-definition, Image, Map generation, Map compilation, Geometric quality