Patent ID: 7167174
Filing Date: 2007-01-23
Classification: G06T

Abstract:
1. A computer program product for use in connection with a computer for generating coordinates for a subdivision surface of an upper level surface element at a predetermined subdivision level from an identifier associated with the subdivision surface, the identifier including a plurality of position codes each identifying a position relative to a higher level, the system comprising computer program product comprising a computer-readable medium having encoded thereon: A. computer-readable program instructions executable to provide a position code selection module configured to enable the computer to select from the identifier one of the position codes; B. computer-readable program instructions executable to provide a relative position determination module configured to enable the computer to determine the position of a subdivision surface associated with the position code relative to a higher level subdivision surface; and C. computer-readable program instructions executable to provide an iteration control configured to enable the computer to control the position code selection module and the relative position determination module through a plurality of iterations, to enable the position code selection module to iteratively select indentifiers associated with successive levels thereby to enable the relative position determination module to determine positions of subdivision surfaces at successive levels, to the predetermined subdivision level; in which the upper level surface element and the subdivision surfaces are triangular; in which in at least one level the number of subdivision surfaces in a surface at a higher level is four, the subdivision surfaces being defined by (i) three line segments interconnecting three points that define the surface at the higher level, and (ii) three line segments, each interconnecting (a) a point that defines the surface at the higher level, and (b) a point on the line segment interconnecting the other two points that define the surface at the higher level, the point dividing the line segment according to a selected ratio; in which the ratio is such that the point dividing the line segment bisects the line segment; and in which the relative position determination module is configured to determine the position of the subdivision surface relative to the upper level surface element in accordance with where (i) “n” refers to the subdivision surface's subdivision level relative to the upper level surface element, (ii) the superscripts “1 . . . n” refer to successive subdivision levels relative to the upper level surface element, (iii) each “M i x ” is associated with the value of the position code “i x ” (“x” ranging from “1” to “n”) associated with the “x-th” subdivision level, where (a) i (b) i (iv) each represents a matrix (v) where e being a vector containing a triple where comprise barycentric coordinates of the three points defining the subdivision surface relative to the upper level surface element.