A linear algorithm for motion of rigid objects using features of parallel lines and optical flow

Various approaches have been proposed toward the problem of restoring three-dimensional (3-D) structures and motion of rigid bodies from image information. Ullman and Huang presented algorithms using point and line correspondences, in which they assume that the correspondence problems can be solved. Prazdny et al., on the other hand, presented an algorithm using optical flow, in which equations become nonlinear and thus the second derivative of velocity is required.

This paper proposes an algorithm which combines optical flow and edge information. First, considering segments consisting of edges in an image, we derive an equation for optical flow. Then, making use of parallelism of line segments, we show that 3-D motion can be restored by using linear equations. To apply the algorithm there must exist two pairs of parallel line segments on an object. This paper presents an algorithm for extracting these pairs of parallel line segments. Finally, we verify the effectiveness of the algorithm by simulation.