Section: New Results

Satellite imaging

Modeling, estimating and compensating the vibrations

Within a collaboration with ASTRIUM, we work on satellite imaging and linear pushbroom cameras. These cameras are widely used in passive remote sensing from space as they provide high resolution images. In earth observation applications, where several pushbroom sensors are mounted in a same focal plane, small dynamic disturbances of the satellite's orientation lead to noticeable geometrical distortions in the images. We have defined a global method to estimate those disturbances, which are effectively vibrations. We exploit the geometry of the focal plane and the stationary nature of the disturbances to recover undistorted images. To do so, we embed the estimation process in a Bayesian framework. An autoregressive model is used as a prior on the vibrations. The problem can be seen as a global image registration task where multiple pushbroom images are registered to the same coordinate system, the registration parameters being the vibration coefficients. An alternating maximisation procedure is designed to obtain Maximum a Posteriori estimates (MAP) of the vibrations as well as of the autoregressive model coefficients. A paper has been submitted to CVPR, and a patent has been applied.