Geometric Accuracy Evaluation of YG ‐18 Satellite Imagery Based on RFM

YaoGan‐18 (YG‐18) is a Chinese high‐resolution synthetic aperture radar (SAR) satellite, which was launched on 29th October 2013. So far, however, there have been no published reports evaluating the geometric accuracy of its imagery; this is rectified in this paper. A refined rational function model (RFM) with an affine transformation is utilised for the spaceborne SAR processing. By setting corner reflectors as ground control points (GCPs) and independent check points, the orthorectification accuracy of YG‐18 satellite images was better than 2·5 m. Its stereo‐SAR measurement accuracy was subsequently evaluated using a high‐precision digital surface model (DSM), achieving an elevation accuracy of 11·36 m. The feasibility of the orthorectification method based on GCPs selected from corresponding image points of YG‐18 SAR images and ZiYuan‐3 (ZY‐3) optical images was also verified, offering single‐image accuracy better than 4·5 m.