Patent ID: 6504957
Filing Date: 2003-01-07
Classification: G01N,G06K,G06T,Y10S

Abstract:
A method of comparing a theoretical N dimensional model surface to N dimensional measured data surface points of an object comprising the steps of:a) acquiring said N dimensional model; b) analyzing said model to determine a plurality of low curvature surface patches Pi, each Pi having a curvature less than a predetermined curvature threshold; c) determining a surface normal vector ni, and center location pi for each of said low curvature surface patches Pi; d) projecting a line from pi to intersect with location qi on the surface data; e) determining a pose error, being a sum of distances d(P, Pâ€²) between locations pi and qi for a plurality of patches i; f) minimizing the sum of distances d(P, Pâ€²) to result in the pose error; g) adjusting the pose of the N dimensional model relative to the N-dimensional data to according to the calculated pose error as a rough pose; h) calculating a statistical distribution of a plurality of data surface points; i) determining deviation from the calculated statistical distribution of a plurality of data surface; j) comparing the each of the plurality of data surface points to the statistical distribution; k) attributing a weight to each of the plurality of surface data points based upon the comparison to the statistical distribution, being between 1 and 0, with the weight going toward 0 as the distance from the center of the statistical distribution increases. l) multiplying each range data point by its weighting to result in weighted surface data; m) repeating steps (b) through (g) above to solve for fine pose using the weighted measured data in place of the original measured data; n) adjusting the rough pose of the N dimensional model relative to the N-dimensional surface data to according to the calculated pose error from the weighted measured data.