Shadow carving

Abstract

The shape of an object may be estimated by observing the shadows on its surface. We present a method that is robust with respect to a conservative classification of shadow regions. Assuming that a conservative estimate of the object shape is available, we analyze images of the object illuminated with known point light sources taken from known camera locations. We adjust our surface estimate using the shadow regions to produce a refinement that is still a conservative estimate. A proof of correctness is provided. No assumptions about the object topology are made, although any tangent plane discontinuities over the object's surface are supposed to be detectable. An implementation and some experimental results are presented.