Post-launch analysis, calibration, and validation of CCD line of sight for a space-borne push-broom electro-optical sensor using a global image data set

This article describes a technique which estimates line-of-sight LOS parameters of each CCD array in a high-resolution electro-optical sensor on board a satellite using statistical information which is extracted automatically from a large number of real images acquired after launch. First, the focal length of panchromatic PAN CCD arrays is estimated by using thousands of ground control points GCPs converted to raw image space. Second, a model is introduced for deriving LOS parameters for multispectral MS CCD arrays in one focal plane assembly FPA such as the focal lengths and the first/last detector cell positions from automatically matched band-to-band B2B tie-points. Finally, the LOS parameters of all arrays in one FPA are updated using automatically matched tie-points in the overlap zone OZ in order to represent the geometrical relationship between the CCD arrays with the same spectral band in two FPAs. The proposed technique was applied to the calibration of a ground segment image processor for a currently operating high-resolution imaging satellite during its initial commissioning phase. This article describes the accuracy and robustness of the LOS parameters estimated by the proposed technique by using more than one hundred images covering full geographical locations and off-nadir tilt angle ranges.