An Improved Side-Slither Relative Radiometric Calibration Method for WFV Satellite: Taking HY1D CZI as an Example

Wide field of view (WFV) push-broom optical satellites can acquire ground images over hundreds to thousands of kilometers in a single pass, thanks to their large field of view (FOV) cameras consisting of tens or even hundreds of thousands of detectors, which also makes their relative radiometric correction (RRC) difficult. Existing side-slither-based RRC approaches overlook the distinct structural design of WFV push-broom optical satellite cameras, thus failing to rectify nonlinear distortions in side-slither images stemming from the nonflat arrangement of camera detectors. Furthermore, these methods necessitate the corresponding pixels (pixels of the same ground object) covering the entire FOV in side-slither images. However, the brief duration of side-slither imaging makes it unfeasible to cover the entire FOV with calibration data. To address these issues, we propose a novel RRC approach for WFV push-broom optical satellites, achieved based on a thorough analysis of the unique structural traits of WFV push-broom optical cameras, enabling precise standardization of the nonlinear distortions in side-slither data. Additionally, a local-to-global side-slither calibration strategy is proposed to obviate the requirement for corresponding pixels to cover the entire FOV in calibration data. Experiments using the Haiyang-1D Coastal Zone Imager satellite indicate that our method effectively rectified nonlinear distortions in side-slither data, and evident RRC accuracy improvement with that of the existing methods can be obtained.