(19)

(11)

EP 0 920 678 A1

(12)

(43) Date of publication: 09.06.1999 Bulletin 1999/23 (21) Application number: 97936355.0 (22) Date of filing: 01.08.1997

(51) International Patent Classification (IPC):  G06T 15/ 10( . ) (86) International application number: PCT/US1997/013563 (87) International publication number: WO 1998/006067 (12.02.1998 Gazette 1998/06)

(84) Designated Contracting States: BE DE FR GB IT LU NL (30) Priority: 01.08.1996 US 19960023795P 07.08.1996 US 19960023513P (71) Applicant: Intergraph Corporation Huntsville, Alabama 35894-0001 (US)	(72) Inventors: SMITH, George, Randolph, Jr. Madison, AL 35758 (US) SMITH, Karin, P. Madison, AL 35758 (US) STRADLEY, David, John Madison, AL 35758 (US) (74) Representative: Froud, Clive, et al  Elkington and Fife Prospect House 8 Pembroke Road Sevenoaks, Kent TN13 1XR Sevenoaks, Kent TN13 1XR (GB)