Reconstruction of 3D interacting solids of revolution from 2D orthographic views Hanmin Lee * , Soonhung Han Department of Mechanical Engeneering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-Dong, Yuseong-Gu, Daejeon 305-701, South Korea Received 6 September 2004; received in revised form 28 November 2004; accepted 30 January 2005 Abstract 3D CAD is replacing 2D CAD to improve efficiency of product design and manufacturing. Therefore, converting legacy 2D drawings into 3D solid models is required. CSG based approaches reconstruct solid models from orthographic views more efficiently than traditional B-rep based approaches. A major limitation of CSG based approaches has been the limited domain of objects that can be handled. This paper aims at extending the capabilities of CSG based approaches by proposing a hint-based recognition of interacting solids of revolution. This approach can handle interacting solids of revolution as well as isolated solids of revolution. q 2005 Elsevier Ltd. All rights reserved. Keywords: Solid reconstruction; Interacting solids of revolution; Hint-based recognition; Orthographic projections 1. Introduction Two-dimensional engineering drawings have been a staple of the design process since the late 18th century, when the principles of orthographic projection and descrip- tive geometry were first developed and applied to engineering problems. 2D drawings still play an important role in engineering practice, and in many cases serve as the definitive design documentation that guides manufacture, fabrication, and assembly of products. However, 2D drawings have critical limitations that unnecessarily extend design cycle time, compromise product quality, and increase engineering and manufacturing costs. These weaknesses primarily arise from the aspects that it is difficult to inspect 2D design data intuitively and to verify it without physical prototyping and to use it directly in downstream processes. It is necessary to convert existing 2D drawings into 3D solid models, because 3D solid models can overcome the limitations of 2D drawings. There have been two general approaches for solid reconstruction according to the solid representation schemes used: B-rep based approach and CSG based approach [6,7]. The B-rep based approach has a relatively wider domain of objects that can be reconstructed than the CSG based approach. However, it cannot reconstruct complex objects effi- ciently due to exhaustive search and computation, and ambiguity may occur. The CSG based approach is relatively more efficient and often provides a unique solution, because it generally employs Boolean oper- ations that ensure the validity of geometric models, thus avoiding the creation of nonsense objects. However, it has a limited domain of objects because it typically uses either pre-defined 2.5D primitives or identifies only entities that can be extruded. The purpose of this paper is to extend the capabilities of the CSG based approach by proposing a procedure to reconstruct solids of revolution from orthographic views. A hint-based method is proposed to recognize interacting solids of revolution as well as isolated ones using minimal conditions. This approach is restricted to recognizing axis- aligned solids of revolution (axis of revolution is normal to one of the planes of projection). Computer-Aided Design 37 (2005) 1388–1398 www.elsevier.com/locate/cad 0010-4485//$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.cad.2005.01.007 * Corresponding author. Tel.: C82 42 869 3080; fax: C82 42 869 3210. E-mail addresses: komaa@icad.kaist.ac.kr (H. Lee), shhan@kaist.ac.kr (S. Han).