Exploring objects by invariant-based tangential viewpoint control

What viewpoint control strategies are important for exploring the shape of unknown, curved objects? The authors argue that strategies that control viewpoint on the tangent plane of automatically-selected points projecting to the occluding contour can be very useful for local, global, qualitative, as well as quantitative shape recovery. This paper studies the design and implementation of an uncalibrated hand-eye system for tangential viewpoint control. The authors show that tangential viewpoint control can be accurately performed in real time using an uncalibrated camera to control a robot manipulator with at least three degrees of freedom. The only requirement is that at least four points can be identified on the robot's end-effector and can be tracked across frames.