Digitizing apparatus with extension-intersection measuring function

A digitizing apparatus for obtaining form data of a subject three-dimensional model by scanning measurement lines on the surface of said three-dimensional model using a stylus of a tracer head, said digitizing apparatus comprising:

• a continuous cycle scanning measuring section for measuring coordinates of points on said measurement lines which are positioned at intervals of a constant scanning distance of said stylus;
• a measured-coordinate temporary storage section for temporarily storing the coordinates of the points on said measurement lines;
• an extension-intersection calculating section for determining associated sets of points from among the points on said measurement lines which extend along a same respective straight line in accordance with the coordinates read from said measured-coordinate temporary storage section, for extracting straight lines for the associated sets of points, and for calculating an extension-intersection as an intersection of two neighboring straight lines;
• an extension-intersection storage section for storing the extension-intersection calculated in said extension-intersection calculating section;
• and
• a data comparison and collation output section for comparing and collating the coordinates of the intersection read from said extension-intersection storage section and previously prepared and stored coordinates of intersections on a drawing so as to output results of said comparison and collation denoting a deviation error between the coordinates of the intersection of the three-dimensional model and the coordinates of intersections on the drawing.