Towards robust metric reconstruction via a dynamic uncalibrated stereo head

We consider the problem of metrically reconstructing a scene viewed by a moving stereo head. The head comprises two cameras with coplanar optical axes arranged on a lateral rig, each camera being free to vary its angle of vergence. Under various constraints, we derive novel explicit forms for the epipolar equation, and show that a static stereo head constitutes a degenerate camera configuration for carrying out self-calibration. The situation is retrieved by consideration of a stereo head undergoing ground plane motion, and new closed-form solutions for self-calibration are derived. An error analysis reveals that reconstruction is adversely affected by inward-facing camera vergence angles that are similar in value, and by a principal point location whose horizontal component is in error. It is also shown that the adoption of domain-specific robust techniques for computation of the fundamental matrix can significantly improve the quality of scene reconstruction. Experiments conducted with dynamic stereo head images confirm that avoidance of near-degenerate configurations and use of robustness techniques are essential if reliable reconstructions are to be attained. (C) 1998 Elsevier Science B.V. All rights reserved.