Recovering shape by purposive viewpoint adjustment

An approach for recovering surface shape from the occluding contour using an active (i.e., moving) observer is presented. It is based on a relationship 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. 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 is used. It is shown that there is a simple and efficient viewing strategy that allows the observer to align the viewing direction with one of the two principal directions for a point on the surface. Experimental results demonstrate that the method can be easily implemented and can provide reliable shape information