Real-Time Implementation Of Digital Stabilization For High Resolution Earth Observation Imaging

In order to increase Signal to Noise Ratio of very high resolution Earth observation satellites images, Time Delay Integration (TDI) sensors are usually used. A TDI device synchronizes the electronic charge transfer with the satellite speed to virtually increase exposure time and thus signal to noise ratio. It is sensitive to high frequency attitude disturbances which may induce blurring effects when increasing time exposure. In this paper, we present an on-board satellite implementation of multiframe registration to improve classical TDI performances. A solution to no longer constrain the number of lines to be accumulated would be to compute, in real-time, the shift between each line and resample them before summation. A motion sensor dedicated to shift measurements would be added in the focal plane. Then a fast real-time algorithm will compute shift between two consecutives images delivered by the motion sensor. The optimization study of the motion sensor and the performances of a gradient-based algorithm on these images will be presented.