Construction for Curved Surfaces of Solid Objects from Orthographic Three-View Drawings with Curved Lines Approximated by Straight Lines.

Abstract

This paper deals with an algorithm for constructing curved surfaces of solid objects based on orthographic three view drawings. At first, all curved lines in the drawings are approximated by straight lines, for the simplification of the expression of complicated curves. The approximation by the straight lines transforms a curved surface of the solid model into many small planes. However, the approximation causes many ghost points in wire-frame model, and these points produce many ghost lineS. To prevent the occurrence of the ghost points, the three dimensional (3-D) data for nodes and edges on the small planes are computed previously during the construction of the three-view drawings. As soon as the solid objects are generated from the three-view drawings except for the approximate straight lines, the 3-D data are used. Then, the 3-D data makes it possible to eliminate the ghost points dependent on the approximation by straight lines in the drawings. Hence, the validity of this algorithm is conformed from the transformation of various curved surfaces into many small plane based on orthographic three view drawings.