Accuracy analyses of a fixed-wing UAV equipped with SPAN CPT for direct georeferencing and DSM generation

The purpose of this study is to develop a UAV imaging system capable of fast disaster surveying and stereo mapping. Thus, a fixed-wing UAV equipped with a SPAN-CPT and a Canon EOS 5D Mark II DSLR camera are used for aerial image acquisition. For system calibration, an in-door camera calibration field is designed for the calibration of interior orientation parameters (IOPs) and a two-step boresight and lever-arm calibration procedure is used for boresight / lever-arm calibration. The performance of the whole system will be evaluated including accuracy of bundle block adjustment through different aerial triangulation (AT) software, the precision of system calibration, the accuracy of stereo mapping, the accuracy of direct geo-referencing (DG), and the accuracy of the generate DSM. Experimental results show that the precision of the generated DSMs by non-control and controlled AT are 0.9 m and 0.51 meters, respectively. It proves that the elevation accuracy is high for landslide volume loss estimation after disaster even control points are not utilized and the use of DSLR camera for aerial mapping is promising for stereo mapping. In the meantime, the RMS errors of DG in planimetric and vertical directions are both less than 1 m and 4 m, respectively. This is acceptable for a flight height of 1200 m and for the purpose of fast hazard investigation.