Proposes a method for the estimation of point correspondences between boundaries undergoing nonrigid motion. The algorithm works in two stages. In the first stage, a global estimate of the nonrigid motion is obtained using hyperquadric models. The second stage uses this estimate to remove the global nonrigid motion (scale, shear, etc.) and then compute point correspondences between the two datasets assuming small deformations. The global part of the nonrigid motion (scale, shear, rotation and translation) is estimated by modeling the object with hyperquadrics and estimating the transformation between the hyperquadric parameters. Point correspondences are then estimated by using differential geometric properties during small deformations. Experimental results with real data are presented.

Algorithms for computing the aspect graph representation are generalized to include a larger, more realistic domain of objects known as articulated assemblies those objects composed of rigid parts with articulated connections allowed between parts. The generalization suggests two slightly different representations: one that directly summarizes the possible general views of the object and another (hierarchical) form summarizing the possible general configurations and their respective views. Algorithms are outlined for computing both representations. The generalized aspect graphs of assemblies formed using translational connections are examined.>

Consideration is given to a generalization of the aspect graph concept which is applicable to objects which may have articulated connection between their (rigid) parts. This generalization is a major step forward in terms of applying the aspect graph concept to a larger and more realistic domain of objects. An algorithm for computing the generalized aspect graph is described, and an example is analyzed in detail.>