Comprehensive analysis of inherent image motion characteristics in area-array staring imaging for low-illumination remote sensing applications

Many researchers have striven to expand the applications of area-array satellites to dawn–dusk and low-light imaging scenarios. In our previous studies, we proposed the inherent image motion theory for area-array systems operating in the along-track staring imaging mode and concluded that, when adopting the along-track staring mode, low-Earth-orbit (LEO) satellites with large area-arrays are ill-suited for low-illumination imaging applications. The reason is that long-exposure staring with large area-arrays leads to significant image-motion challenges, which consequently limit the allowable exposure time, especially under off-nadir-view conditions. To enhance the completeness of the inherent image motion theory, this study systematically examines the image motion characteristics under other staring modes. First, we derive analytical expressions for the three types of image motions that occur during across-track staring: angle-rotation image motion, size-scaling image motion, and Earth-rotation image motion. Co-simulations in MATLAB and Systems Tool Kit (STK) validate the expressions with strong theoretical-simulated correlation. Furthermore, we elucidate the fundamental mechanism underlying angle-rotation image motion and extend its application to other staring modes. We not only demonstrate the existence of an upper bound for exposure time during the staring imaging process but also propose an optimal staring mode to attain this upper bound for any rectangular area-array sensors. Consequently, we achieve a comprehensive theoretical description of area-array staring image motion and reveal that LEO satellites equipped with large-scale area-arrays experience significant image-motion-induced blur under low-illumination conditions, regardless of the staring mode adopted. The inherent image motion theory presented in this study is specifically formulated for area-array staring imaging applications in LEO remote sensing satellites and demonstrates adaptability to MEO/GEO scenarios as well as aerial platforms utilizing area-array sensors.