Geometric Errors of Remote Sensing Images Over Forest and Their Propagation to Bidirectional Studies

This study focused on the need of accurate digital surface models rather than existing digital terrain models for the geometric correction of high spatial resolution images over forests. Based on both theoretical and experimental results, it was shown here that even for close to nadir observations (view angles less than 7°), the geometric error increased from within to beyond the pixel level when not taking into account the canopy height. This is particularly relevant for forest studies on bidirectional effects, data fusion and change detection techniques. The propagation of geometric errors for studies on bidirectional effects was quantified as a case study here, showing that geometric errors can easily mask such effects.