Image motion analysis and compensation for dynamic push-broom imaging with TDI detectors

Abstract

This paper studies the inherent image motion, solely introduced by the orbital motion and Earth’s rotation during along-track dynamic TDI imaging, based upon the assumption that the ideal attitude compensation is achieved, and the perfect satellite platform is employed. After being classified into the angle-rotation, size-scaling, and Earth-rotation image motions, the characteristics of the inherent image motion are systematically analyzed. To the best of our knowledge, the size-scaling image motion is discussed for the first time, which has never been noticed during traditional imaging but is significant during dynamic push-broom imaging. Through theoretical derivation and scene simulations, a recipe is provided and verified for image motion compensation by adjusting the row frequency of each splicing sensor and the center of imaging time. It is discovered that there exists a physical upper limit on the exposure time for any camera during dynamic TDI imaging, which is crucial to evaluating the maximum signal-to-noise ratio (SNR) and the area of application of the camera. The image motion compensation method is applicable to approaching the theoretical upper limit for high image quality when along-track dynamic push-broom imaging is adopted.