1. Graduate Student, Program of Computer Graphics, Cornell University, Ithaca, N.Y.
2. Assistant Professor and Director, Computer Science Robotics Laboratory, Department of Computer Science, 4130 Upson HalI, Cornell University, Ithaca, N.Y.
3. Director, Program of Computer Graphics, Jacob Gould Shurman Professor of Computer Graphics, Cornell University, Ithaca, N.Y.