COMPRESSION SYSTEM, COMPRESSION PROGRAM, DECOMPRESSION SYSTEM, AND DECOMPRESSION PROGRAM FOR POLYGON DATA

PROBLEM TO BE SOLVED: To propose a new geometrical compression method for effectively reducing numerical information of vertex coordinates of polygon data. SOLUTION: A difference vector calculation part 1 expresses a vertex Pn to be processed as a difference vector dn as a difference between the vertex Pn and a previous vertex Pn-1. A local basis calculation part 4 calculates a three-dimensional local basis B concerning the difference vector dn. A local transformation part 2 carries out the local transformation of the difference vector dn based on the local basis B. A mantissa truncation part 3 truncates the low order bits of a mantissa part in accordance with the magnitude of the exponent part concerning the respective components α, β, and γ of a difference vector d'n subjected to the local transformation. COPYRIGHT: (C)2009,JPO&INPIT