Cue circles: image feature for measuring 3-D motion of articulated objects using sequential image pair

The shape of articulated objects such as the human body can be simplified into a stick model which is represented by connections of several circular generalized cylinders (GCs). The authors propose a new image feature called cue circles (CCs), and present a method for obtaining CCs from input images. Using CCs, 3D motion of the human body is measured from a sequence of boundary contour image pairs, which is obtained by an active binocular sensor system. The body model used is represented by a set of cue spheres (CSs), each of which is located at ends of GCs. Stereo matching for recovering the body model is carried out by finding pairs of CCs between the pair of contour images under consideration: a CS is projected on the two image planes as its corresponding CCs.