ACQUIRING 3-D MODELS FROM SEQUENCES OF CONTOURS

This paper explores shape from contour for acquiring 3-D graphics mode ls. In this method, a continuous sequence of images is taken as an obj ect rotates. A smooth convex shape can be estimated instantaneously fr om its contour and by the first derivative of contour movement (trace of contour, or contour distribution with time). We also analyze shapes that do not satisfy the conditions of smoothness and visibility, whic h are indispensable for modeling an object. A region that does not exp ose as contour yields a nonsmoothness in the tracked contour movement. We can thus detect such a region by contour distribution filtering an d extract its accurate location by computing the left and right deriva tives of the distribution. This has not been studied previously. These unknown regions are obtained for further investigation using other vi sual cues. A general approach for building a geometrical object model using contours is then described. The entire process from silhouettes to a 3-D model is based on local computation; this is promising for pr oducing shapes in real time. Our direct goal is to establish 3-D graph ics models of human races for the growing needs of visual communicatio ns. We have obtained some good results.