SPACEBORNE SAR IMAGERY STEREO POSITIONING BASED ON RANGE-COPLANARITY EQUATION
Keywords: rigorous positioning, side looking radar, R-Cp equation, exterior orientation elements, SAR
Abstract. Stereo positioning is a important content for Spaceborne SAR imagery mapping, which is still lack of investigation depend on exterior orientation elements. In this paper, we firstly introduced the Range-Coplanarity (R-Cp) geometric imaging equation and its character for radar imagery, compared the difference and relationship between R-Cp and R-D model, and build stereo positioning rigorous model for spaceborne SAR imagery based on the R-Cp equation, satellite orbit, and pose refinement model. Then separate taking TerraSAR-X images in mountainous terrain observed from same and opposite side-looking direction as test data, we presented the initial attitude value acquirement method for TerraSAR-X image after moving compensation, analyzed stereo positioning precision according to amounts and spatial distributions of GCPs and lengths of baseline between SAR antennas, and also compared the precision with R-D model. the proposed stereo positioning model avoids SAR signal imaging parameters during the geometric processing, with one GCP it could improved the plan and height precision from (17.9m,29.2m) to (10.3m,6.1m) in the test of opposite side-looking direction images, and even had a better accuracy than R-D model when more GCPs were used, which indicate that R-Cp model have a potential application in spaceborne SAR image stereo positioning.