Orientation of Spaceborne SAR Stereo Pairs Employing the RPC Adjustment Model

Since the adoption of the rational polynomial coefficient (RPC) adjustment model as a preferred sensor orientation model for high-resolution optical satellite imagery, it has been demonstrated to be effective and robust. However, no publication discusses the application of the RPC adjustment model to the 3-D intersection from SAR stereoscopic pairs. This paper aims to validate the RPC adjustment model for spaceborne SAR stereoscopic orientation. Initially, a brief summary of the mathematical background of the RPC model is presented. Then, the SAR orientation errors are analyzed, namely, the orientation parameters, having the same net effect on the object-image relationship, and combined into a single adjustment parameter. The required adjustment is then discussed, and the formulation of the adjustment model is outlined. Finally, a number of designed adjustment experiments controlled via well-surveyed corner reflectors and an existing digital elevation model plus a digital orthophotograph map at the scale of 1:10 000 are performed. Multisensor images of TerraSAR-X, COnstellation of small Satellites for the Mediterranean basin Observation (COSMO-SkyMed), and Satellite Pour l'Observation de la Terre-5 (SPOT-5) over the Guangzhou area are used as test data. The results demonstrate that the proposed method can be generally applied to different imaging systems or the stereoscopic fusion of combined data and can achieve high orientation accuracy.