It makes the drawing instruction in the line drawing on the basis of the curved surface with respect to 3 dimensional

摘要

PROBLEM TO BE SOLVED: To provide a display method for three-dimensional shape that can easily and surely discriminate the kinds of a curved surface and a loop, and a three-dimensional CAD system using the method by evading the complicatedness of a screen caused by the limitation of display colors and the overlapping of lines. ;SOLUTION: To display a curved surface in a three-dimensional space in two dimensions, the three-dimensional shape display method, which can discriminate individual curved surfaces or loops calculates the normal or tangent of a curved surface or loop at a point meeting previously set conditions and displays a segment, whose direction matches the calculated normal or tangent as a marker to make discrimination. Further, the length of the marker is calculated by a previously set calculating method to make its display easy to see. The figure shows a display marker obtained from obtained from normals at the middle points of respective ridges of a curved surface or loop consisting of the four ridges. The three-dimensional CAD system is equipped with a means, which displays the curved surface or loop by this three-dimensional shape display method.;COPYRIGHT: (C)1998,JPO