1. Agin, G.J., and Binford, T.O., 1973. Computer description of curved objects,3rd Intern. Joint Conf. Artif. Intell., Stanford, CA, p. 629?635. August.
2. Allen, P.K., 1986. Sensing and describing 3-d surfaces,Proc. 1986 Conf. Robot. Autom. IEEE, San Francisco, April.
3. Arkin, R.C., 1987. Toward cosmopolitan robots: Intelligent navigation in extended man-made environments, Tech. Rept. 87-80, COINS Department, University of Massachusetts, September.
4. Asada, H., and Brady, J.M., 1985. The curvature primal sketch, Tech. Rept. AIM-758, Massachusetts Institute of Technology.
5. Baker, H., 1977. Three dimensional modeling,5th Intern. Joint Conf. Artif. Intell., Cambridge, MA., p. 649?655.