Satellite platform stability estimation using image matching

Recent Indian remote sensing satellite Cartosat-2B uses detectors in stagger mode (odd and even) with 5 scan lines separation (in focal plane) in along track direction. This arrangement in general is used to improve the MTF of the image. The stagger value between odd and even pixels varies from scene to scene depending on the variation of the dynamic component of the orbit and attitude values which in turn represents the platform stability. Using image matching between this pair, one can find relative control points (RCP) at regular interval. The differences in these RCPs, especially in along track direction between two images can be converted in time. Platform instability will lead to varying displacement in scan direction for relative control points. Therefore the time series for control points can be used to derive the platform frequencies. These frequencies essentially represent the behaviour of platform in time. The present paper talks about the methodology adopted to exploit the separated images from two detectors using image matching and later converting in to platform behaviour in terms of frequencies.