Solving the orientation-duality problem for a circular feature in motion

Circular features have been commonly used in numerous computer vision application areas for 3-D pose estimation. However, the estimation of such a feature’s pose from 2-D image coordinates results in an orientation-duality problem. Namely, although the 3-D position of the circle’s center can be uniquely identified, the solution process yields two different feasible orientations, of which only one is the true solution. This duality problem is normally addressed through the acquisition of a second image in the case of a “static” feature. This solution, however, would not be applicable to “features in motion”. In this paper, several methods are presented for the solution of the orientationduality problem for circular features that are in motion. The first approach is applicable to those features moving on a 3-D line with constant orientation or to those which are moving on a plane with general motion. The second approach relies on the existence of additional object features, such as points or lines, which are co-planar to the circular