Occluding contour detection using affine invariants and purposive viewpoint control

We present an approach for identifying the occluding contour and determining its sidedness using an active (i.e., moving) observer. It is based on the non-stationarity property of the visible rim: When the observer’s viewpoint is changed, the visible rim is a collection of curves that “slide,” rigidly or non-rigidly, over the surface. We show that the observer can deterministically choose three views on the tangent plane of selected surface points to distinguish such curves from stationary surface curves (i.e., surface markings). Our approach demonstrates that the occluding contour can be identified directly, i.e., without first computing surface shape (distance and curvature).