Projective Rotations applied to a Pan-Tilt Stereo Head

A non-metric pan-tilt stereo-head consists of a weakly calibrated stereo rig mounted on a pan-tilt mechanism. It is called non-metric since neither the kinematics of the mechanism, nor camera calibration are required. The Lie group of "projective rotations"- homographies of projective space corresponding to pure rotations -- is an original formalism to model the geometry of such a pan-tilt system. A Rodrigues alike formula as well as a minimal parameterization of projective rotations are introduced. Based on this, the practical part devises a numerical optimization technique for accurately estimating projective rotations from point correspondences, only. This procedure recovers sufficient geometry to operate the system. The experiments validate and evaluate the proposed approach on real image data. They show the weak calibration, image prediction, and homing of a non-metric pan-tilt head. 1 Introduction One of the most useful sensors in computer vision is a pan and tilt stereo head. S..