Patent ID: 6191791
Filing Date: 2001-02-20
Classification: G06T

Abstract:
A method for compressing a surface-normal, the surface-normal specified by a latitude and a longitude within a surface-normal-coordinate-system, for a point on a surface of a three-dimensional-figure into a quantized-surface-normal, the quantized-surface-normal specified by identifying a unit-sphere-quantized-surface-normal whose value equals a unit-sphere-tile-number assigned to a unit-sphere-tile within a unit-sphere-latitude-band having a unit-sphere-latitude-band-width on a unit-sphere, wherein the unit-sphere is tessellated into a maximum-number-of-unit-sphere-tiles, wherein the latitude and the longitude of the surface-normal lie within the unit-sphere-tile, wherein an equator-number-of-quantized-surface-normals are placed around a unit-sphere-equator of the unit-sphere, and wherein intermediate variables a number-quantized-surface-normals-below-latitude-band, a number-quantized-surface-normals-below-next-latitude-band, and a number-quantized-surface-normals-in-latitude-band are used, comprising the steps of:(a) tessellating the unit-sphere into approximate replicas of the unit-sphere-tile;(b) obtaining the surface-normal of the point on the surface of the three-dimensional-figure;(c) assigning the unit-sphere-tile-number of the unit-sphere-tile within which the surface-normal lies to the quantized-surface-normal; and(d) storing the quantized-surface-normal in a computer-memory.