Method of determining mesh data and method of correcting model data

A method of correcting model data, comprising the steps of:

• correcting an actual model fabricated based on reference model data and measuring the corrected actual model with a measuring instrument to provide three-dimensional measured actual model data;
• and
• placing the three-dimensional measured actual model data and the model data in proximity to each other, and projecting a first surface represented by the model data onto a second surface represented by the three-dimensional measured actual model data using a computer;
• wherein the step of projecting the first surface comprises the steps of:
• a first step of determining normal lines or average normal lines including peripheral areas with respect to a plurality of reference points set on the first surface;
• a second step of determining intersecting points between the normal lines or the average normal lines and the second surface;
• and
• a third step of moving the reference points along the normal lines or the average normal lines to a position at a predetermined ratio up to the intersecting points, thereby providing a moved and corrected surface.

A method of determining mesh data by measuring a surface shape of a workpiece with a measuring instrument to produce mesh data made up of a plurality of mesh elements, and thereafter identifying noise areas within the mesh data using a computer, the method comprising the steps of:

• a first step of identifying, within the mesh data, a predetermined reference node and all adjacent nodes that are adjacent to the reference node, with sides of the mesh elements interposed therebetween;
• a second step of determining an average surface with respect to the all adjacent nodes;
• a third step of determining a distance between the average surface and the reference node;
• and
• a fourth step of judging the reference node as a normal node if the distance is smaller than a predetermined threshold, or as a noise node if the distance is equal to or greater than the predetermined threshold.