Patent ID: 6873342

Claim:
A method for generating a detail directed hierarchical representation of orientations of a surface of a graphics model, comprising the steps of: partitioning the surface of the graphics model into a plurality of surface cells, each surface cell enclosing a portion of the surface, wherein the surface cells include a root surface cell, intermediate surface cells, and leaf surface cells; storing the surface cells in a hierarchical data structure having a plurality of levels, wherein the number of levels for a particular portion of the surface is determined by surface detail of the particular portion; determining, for each surface cell, a visibility element of the enclosed portion of the surface, the visibility element specifying an axis and a spread defining a range of normal values of the enclosed portion of the surface, wherein the determining further comprises; determining the axis and the spread of the visibility element for each leaf surface cell by sampling a plurality of locations associated with the cell; and determining the visibility elements for the intermediate and root surface cells from the visibility elements of the leaf surface cells; and storing the visibility element with the associated surface cell.