ANALYZING SCENE GEOMETRIES FOR STEREO PUSHBROOM IMAGERY

Bundle Adjustment (BA) is an important step in deriving high quality terrain products from stereo pairs of satellite imagery. Most satellites use pushbroom cameras for image acquisition due to improved signal to noise ratio. The BA process is not as well constrained for pushbroom imagery as it is for frame cameras. Due to the loss of perspective along track additional degrees of freedom are present in BA. Usually Ground Control Points (GCPs) are used to provide necessary constraints. However in order to reduce cost and allow automated processing GCPs are being excluded from BA and Path Control Points (PCPs) are used instead. Without ground control, scene geometry and the technique for describing the camera’s path become more critical. In this paper we study the effects that different scene geometries have on the accuracy of the reconstructed terrain. A method to identify degrees of freedom is developed and utilized to constraints of five commonly used geometries. Theoretical results are supplemented with the numerical analysis of the geometries used in satellite and aerial imagery.