Affiliation: | a Evans & Sutherland Computer Corp., 600 Komas Drive, P.O. Box 58700, Salt Lake City, UT 84158, USA b Computer Graphics Lab (EPFL-LIG), Swiss Federal Institute of Technology, 1015, Lausanne, Switzerland c DIST — Department of Telecommunications, Computer and System Sciences, University of Genoa, Via Opera Pia 13, 16145, Genova, Italy d AT&T Research Laboratories, Room HO 4E518, 101 Crawfords Corner Road, Holmdel, NJ 07733-3030, USA e MIRALab — CUI, University of Geneva, 24 rue du Général-Dufour, CH1211, Geneva 4, Switzerland f Bell Laboratories, Lucent Technologies, Room 2B-231, 600 Mountain Avenue, Murray Hill, NJ 07974, USA |