language: en

Recovering Shape by Purposive Viewpoint Adjustment

Kiriakos N. Kutulakos Charles R. Dyer
Computer Sciences Department University of Wisconsin
Madison, Wisconsin 53706
Technical Report #1035 August 1991

Abstract We present an approach for recovering surface shape from the occluding contour using an active (i.e., moving) observer. It is based on a relation between the geometries of a surface in a scene and its occluding contour: If the viewing direction of the observer is along a principal direction for a surface point whose projection is on the contour, surface shape (i.e., curvature) at the surface point can be recovered from the contour. Unlike previous approaches for recovering shape from the occluding contour, we use an observer that purposefully changes viewpoint in order to achieve a well-defined geometric relationship with respect to a 3D shape prior to its recognition. We show that there is a simple and efficient viewing strategy that allows the observer to align their viewing direction with one of the two principal directions for a point on the surface. This strategy depends on only curvature measurements on the occluding contour and therefore demonstrates that recovering quantitative shape information from the contour does not require knowledge of the velocities or accelerations of the observer. Experimental results demonstrate that our method can be easily implemented and can provide reliable shape information from the occluding contour.

[The support of the National Science Foundation under Grant No. IRI-9002582 is gratefully acknowledged.]