Satellite pushbroom scanners deviate from their predetermined positional and rotational trajectories causing geometric distortion in their scanned imagery. Attitude and orbit control systems usually supply sufficient data for the actual trajectory to be reconstructed through splined interpolation. Geometric correction of imagery requires that image pixels be retroprojected onto the scene surface from points along the reconstructed trajectory and the scene subsequently resampled in a regular tessellation. Since this retroprojection can be very computationally expensive, a trajectory model is used which facilitates an efficient iterative subsampling ray-tracing algorithm. Actual SPOT satellite trajectory data is used for demonstration purposes.
Fergal P. Shevlin, Fergal P. Shevlin,
"Splined trajectory models for geometric correction and fusion", Proc. SPIE 2579, Image and Signal Processing for Remote Sensing II, (17 November 1995); doi: 10.1117/12.226853; https://doi.org/10.1117/12.226853