Accuracy Assessment of UAV photogrammetry for Large Scale Topographic Mapping

Now a day's Unmanned Aerial Vehicle (UAV) replaces the aeroplane flown by a pilot, and a small high-resolution digital camera replaces the large metric camera, the combination of both are used as a platform for acquiring aerial images, so as called UAV photogrammetry. This study concentrates on the use and the capabilities of UAV photogrammetry for producing topographic maps, and to assess the accuracy of these maps. For that, a lightweight fixed-wing UAV eBee - Sensefly was used as a platform for acquiring aerial digital images of the study area. Before the flight mission, ground control points were established, Leica GS15 GPS determined their 3D coordinates in two sessions of static observations. The digital images were processed using Pix4Dmapper software for producing orthophotos and digital surface models. For accuracy assessment, the root mean square errors (RMSE) is used in which 2.0 cm in Easting, 2.1 cm in Northing and 7.5 cm in Elevation were obtained for orthomosaic and DTM respectively. Based on these assessments, the results showed that the accuracy achieved is following (ASPRS Accuracy Standards for Digital Geospatial Data) within the second and third classes of these standards for horizontal and vertical accuracies. In conclusion, this study shows that UAV photogrammetry can be applied for producing digital maps, orthophotos, contour lines, digital terrain model, digital surface model, and line maps all of them complies with international standards.