Method of synthesizing measurement data of free-form surface

摘要

(a) A surface shape of an object 1 is measured from different positions and/or different directions and plural partial measurement data 2 including common part 1a is obtained. (b) A parametric surface showing the surface shape of each measurement range is formed from the data. (c) A plurality of sampling points are set at a predetermined pitch in the common part and the Gaussian curvature K and/or an average curvature H are calculated from the principal curvatures ( kappa 1, kappa 2) in the points. (d) Three or more characteristic points are selected in accordance with the order from larger absolute values of K or H in the common part and a normal vector of a plane constructed by three points among the points is calculated. (e) The common parts are made coincide with each other by moving the parametric surfaces so as to coincide the three characteristic points with each other and to coincide the directions of the normal vectors with each other. Consequently, the synthesis data can be formed from the partial measurement data obtained from the free-form surface.