Building global surface models by purposive and qualitative viewpoint adjustment

We present an approach for recovering a global surface model of an object from the deformation of the occluding contour using an active (i.e., mobile) observer able to control its motion. In particular, we consider two problems: (1) How can the observer's viewpoint be controlled in order to generate a dense sequence of images that allows incremental reconstruction of an unknown surface, and (2) how can we construct a global surface model from the generated image sequence? We achieve the first goal by purposefully and qualitatively controlling the observer's instantaneous direction of motion in order to control the motion of the visible rim over the surface. We achieve the second goal by using a stationary calibrated trinocular camera rig and a mechanism for controlling the relative position and orientation of the viewed surface with respect to the trinocular rig. Unlike previous shape-from-motion approaches which derive quantitative shape information from an arbitrarily generated sequence of images, we develop a collection of simple and efficient viewing strategies that allow the observer to achieve the global reconstruction goal by maintaining specific geometric relationships with the viewed surface. These relationships depend only on tangent computations on the occluding contour. To demonstrate the feasibility and effectiveness of our approach we apply the developed algorithms to synthetic and real scenes.