Determining articulated motion from perspective views: a decomposition approach

The problem is to estimate the 3D motion of an articulated object, such as a robot arm or a human body, from a monocular sequence of 2D perspective views. We advocate an approach of decomposition. The object is decomposed into simpler parts, each containing a small number of links. We estimate the motion of the simplest part(s) and then propagate the analysis to the remaining parts of the object. Human gait is used as an example; however, the approach is general. To use this approach, we need results for the motion of simple articulated objects: motion estimation algorithms, and number of solutions (especially, how many views are needed for uniqueness). With the help of algebraic geometry, we have results for a number of cases which are particularly useful for human gait analysis.