Determining the Instantaneous Axis of Translation from Optic Flow Generated by Arbitrary Sensor Motion

摘要

This paper develops a simple and robust procedure for determining the instantaneous axis of translation from image sequences induced by unconstrained sensor motion. The procedure is based upon the fact that difference vectors at discontinuities in optic flow fields generated by sensor motion relative to a stationary environment are oriented along translational field lines. This is developed into a procedure consisting of three steps: (1) locally computing difference vectors from an optic flow field; (2) thresholding the difference vectors; and (3) minimizing the angles between the difference vector field and a set of radial field lines which correspond to a particular translational axis. This method does not require a priori knowledge about sensor motion or distances in the environment. The necessary environmental constraints are rigidity and sufficient variation in depth along visual directions to endow the flow field with discontinuities. The method has been successfully applied to noisy, sparse, and low resolution flow fields generated from real world image sequences.