ATTITUDE RESTITUTION FOR MULTISPECTRAL EARTH OBSERVATION SATELLITE USING SPACE TRIANGULATION TECHNIQUE

Abstract

Earth observation satellites are equipped with navigation components (star trackers, gyroscopes) which estimates the attitude of the satellite, corresponding to its orientation in the orbital reference frame. This equipment is essential for the localisation of the images which is done a posteriori and for the registration of the different images for a pushbroom sensor. This concerns both the registration of the spectral bands and the registration of multi-temporal series. However, the required accuracy is not always compatible with the performance of the attitude restitution. Moreover, some specific applications need more stringent geometric control even if requirements are met. With a multi-spectral pushbroom instrument, the same object on ground is seen as many times as number of spectral bands at different time instants: the attitude profile of the platform can be completely reconstructed from the results of the mapping of the different spectral bands. An attitude reconstruction method is proposed based on space triangulation inversion technique. The framework of this study is low-frequencies noise perturbations applied to Venμs satellite. Cubic splines are used for the attitude error profile, with 60 free parameters. Provided the physical model is representative, we show on two test cases that the convergence is very good. The band registration quality is used as a proxy to assess the performances. Residuals errors are less than 0.05 pixel for all tested band couples.