Computation of scroll image motion velocity of wide coverage optical remote camera

Abstract

According to the feature of a wide coverage space camera, the geometrical relation of scroll imaging was analyzed .The space coordinate transform process from an object point on the earth to the image point in the focal plane was found. Furthermore, the calculation formulas of scroll image motion velocity were deduced based on a round earth model by using the transform of space coordinate system. The effect of relative image motion match error on the image quality was analyzed by the image motion mismatch modulation transfer function(MTFmismatch). By taking a wide coverage space camera for an example, image motion velocities at different scroll angles and different centrifugal angles were researched. Computation results indicate that the image motion velocities and their variation trends with the scroll angle are different in the different positions of image plane. The MTFmismatch caused by mismatch image motion velocity reaches 0.681 at the perigee if the scroll angle is 25° and the TDI stage is 48. The actual field experimental results show that it is necessary to keep the TDI stages within 16 to ensure good image quality.