Active Visual Navigation Using Non-Metric Structure

This paper demonstrates a method of using non-metric visual information derived from an uncalibrated active vision system to navigate an autonomous vehicle through freespace regions detected in a cluttered environment. The structure of 3-space is recovered modulo an affine transformation using an uncalibrated active stereo head carried by the vehicle. The plane at infinity, necessary for recovering affine structure from projective structure, is found in a novel manner by making controlled rotations of the head. The structure is composed of 3D points obtained by detecting and matching image corners through the stereo image sequence. Considerable care has been taken to ensure that the processing is reliable, robust and automatic. Driveable regions are determined from the projection of the affine structure onto a plane parallel to the ground determined using projective constructs. Two methods of negotiating the regions are explored. The first introduces metric information to allow control of a Euclidean vehicle. The second uses visual servoing of the active head to navigate in the affinely described free-space regions.