3D Pose Tracking with Linear Depth and Brightness Constraints

This paper explores the direct motion estimation problem assuming that video-rate depth information is available, from either stereo cameras or other sensors. We use these depth measurements in the traditional linear brightness constraint equations, and we introduce a new depth constraint equation. As a result, estimation of certain types of motion, such as translation in depth and rotations out of the image plane, becomes more robust. We derive linear brightness and depth change constraint equations that govern the velocity field in 3-D for both perspective and orthographic camera projection models. These constraints are integrated jointly over image regions according to a rigidbody motion model, yielding a single linear system to robustly track 3D object pose. Results are shown for tracking the pose of faces in sequences of synthetic and real images. For a color version of this paper and for video result sequences, see http://www.interval.com/papers/1999-006. This paper appears in Proceedings of the IEEE International Conference on Computer Vision, Corfu, Greece. 1999.