Error Characteristics of Parallel-Perspective Stereo Mosaics

This paper analyzes different aspects of the error characteristics of parallel-perspective stereo mosaics generated from an airborne video camera moving through a complex three-dimensional scene. First, we show that theoretically a stereo pair of parallelperspective mosaics is a good representation for an extended scene, and the adaptive baseline inherent to the geometry permits depth accuracy independent of absolute depth. Second, in practice, we have proposed a 3D mosaicing technique PRISM (parallel-ray interpolation for stereo mosaicing) that uses interframe match to interpolate the camera position between the original exposure centers of video frames taken at discrete spatial steps. By analyzing the errors introduced by a 2D mosaicing method, we explain why the "3D mosaicing" solution is important to the problem of generating smooth and accurate mosaics while preserving stereoscopic information. We further examine whether this ray interpolation step introduces extra errors in depth recover from stereo mosaics by comparing to the typical perspective stereo formulation. Third, the error characteristics of parallel stereo mosaics from cameras with different configurations of focal lengths and image resolutions are analyzed. Results for mosaic construction from aerial video data of real scenes are shown and for 3D reconstruction from these mosaics are given. We conclude that (1) stereo mosaics generated with the PRISM method have significantly less errors in 3D recovery (even if not depth independent) due to the adaptive baseline geometry; and (2) longer focal length is better since stereo matching becomes more accurate.