Construction of 3D CAD Models From 2D Orthographic Views

This thesis addresses the problem of constructing 3D CAD models from 2D engineering drawings of the object. Procedures for each step in the popular bottom-up approach are described. In each of the steps in this approach, the capability is extended to handle classes of parts not handled by present art. These include auxiliary views, parts with curved entities that are inclined to all viewing directions, and views that result in non-manifold edges in the surface model. In addition this thesis also presents procedures to extract features from the solid model constructed so that the 3D model can be manipulated and modified within current CAD systems. In order to enable extracting the construction history, detecting symmetry in the part is essential. This thesis presents an algorithm to detect symmetry (both global and partial) in the part given the solid model of the part. Working of the procedures is illustrated using benchmark parts from the literature. The thesis concludes with a discussion on scope for further work