Terrain reconstruction from widely separated images

When a terrain elevation map is computed from widely separated images the perspective distortion may result in a large number of false matches and poor reconstruction accuracy. This paper describes three image matching algorithms designed specifically to process images taken with large base-to-height ratios. They include a new match score, a subpixel interpolation scheme, and a multi-resolution unwarping technique. The algorithms are incorporated into a stereo analysis package and the system is tested by processing a single pair of high altitude images with a base-to-height ratio of 0.63 and a sequence of simulated images with base-to-height ratios that varied between 0.25 and 2.25. Analysis of the simulated data show that when these techniques are implemented the reconstruction accuracy remains independent of the base-to-height ratio.