Conversion of 2D line drawings to 3D models

• Main Author: Yong, Calwin Wearn Tsun.
• Other Authors: Lee Yong Tsui
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Mechanical engineering::Machine shop and drawings
• Online Access: http://hdl.handle.net/10356/53593
• Institution: Nanyang Technological University

This project aims to investigate the theoretical and practical limitations of a geometric reconstruction system which implements an algorithm based on the cubic corner method to convert 2D line drawings into 3D models. Given a cubic corner in a 2D line drawing, it is possible to determine the (x, y, z) coordinates for all endpoints connected to the corner, followed by the planes of faces connected to the corner and subsequently all vertices in the drawing. In theory, the cubic corner method can be used to reliably recover 3D objects from accurate 2D line drawings comprised of cubic graphs; however this is not true in the case of non-cubic graphs, as drawings containing vertices of degree four or higher may not always be recoverable. Some objects were only recoverable when starting from certain cubic corners or were completely unrecoverable. A modified algorithm is proposed to better handle drawings where full object recovery is sensitive to the starting cubic corner as well as objects which are unrecoverable, based on the knowledge that unrecoverable objects are caused due to vertices in a drawing of degree higher than three that cannot be reached during the face traversal process of the cubic corner method. By systematically mapping out such unreachable vertices during each recovery attempt, it is possible to rapidly determine the correct cubic corner to start from if the object is recoverable. Several workarounds are also discussed in this paper to avoid some of the current limitations of the system. Some practical limitations of the reconstruction system concerning the usability of the system are also discussed.