Linear pushbroom model for IRS-1C/D satellite imaging geometry

Assumptions of a simplified linear pushbroom (LPB) camera model are validated by the analysis of IRS-1C/1D satellite ephemeris data. Mathematical expressions are derived for computing the maximum possible change in the velocity of satellite, using nominal orbital parameters. The transformation matrix of above model was determined from differential global positioning system (DGPS) observed GCPs. The simplified LPB model is used for the geometric correction of IRS-1C/1D images and results are compared with the standard DLT method. Investigations have shown that the assumption of constant velocity will not make appreciable error in the model even for a full LISS-III scene imaging time. However, the assumption of constant attitude may not be valid for a full LISS-III scene due to appreciable changes in the satellite attitude during imaging of this scene. This problem can be alleviated by following an adaptive approach in defining separate camera matrices for different image segments such that during their imaging time the sensor attitude does not change significantly. However, for the imaging time of a IRS, PAN sensor sub-scene, the assumption of constant camera attitude will not make any significant error in the model.