Approximation processing method and approximation processing device

Abstract

An approximation processing method for approximating a point group using a curve or a surface defined by control points includes a step of forming an approximated curve (surface) using control points that retain features of a shape; a first calculation step of calculating a closest point closest to each of the data points on the approximated curve (surface); a second calculation step of calculating an error vector that joins the closest point, obtained in the first calculation step, to the data point; and a third calculation step of calculating a corrected control point by moving each of the control points based on the error vector obtained by the second calculation step. The step of forming an approximated curve (surface) and the first to third calculation steps are repeated to make the approximated curve (surface) respectively approximate the curve (surface) of an object configured by the data points. In correcting control points, a simple geometrical algorithm is used for calculating control points to reduce the number of control point convergence operations and thereby to quickly generate a curve or a surface, which approximates the data points of a point group, without having to solve a linear system.