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There exist numerous design intent systems that convert captured information into structured design intent while providing intent representation and retrieval. These systems woefully neglect the design intent that is present in legacy CAD such as 2D drawings and 3D models. We address the issues that arise when dealing with the capture, representation and retrieval of design intent from the legacy CAD data. A definition for design intent in the CAD domain is presented which forms the basis of the proposed approach. The approach uses a unique context-based inference system to capture design intent from legacy CAD data. A brief explanation of context is provided along with the advantages of using context for this task. The need and use of an inference system is detailed. Additionally a prototype system is implemented to address these issues from a software system point of view.Keywords: design intent, legacy CAD, context, inference system. INTRODUCTIONAs the design and the manufacturing processes evolved around the geometric shape of the product, the current generation of CAD systems is based on geometric modeling techniques. These techniques have proved to be deficient as their usefulness is limited to recording detail of the form of the product. Designers are no longer merely exchanging geometric data but more general information about the product such as the design intent, constraints, specifications and manufacturing knowledge. As design becomes increasingly knowledge intensive, the need for computational frameworks to effectively support the formal representation, capture, retrieval and reuse of product knowledge, becomes more critical. While the industry already uses such engineering frameworks to improve their product development process, the bulk of the product knowledge that resides in their current design data, such as 2D drawings and 3D parametric models, needs to be propagated to a more reusable, intelligent and structured format. The goal of this paper is to report on the results of our research in this area and present the approach taken to address some of the issues that arise when capturing design intent from legacy CAD. One significant result of our survey is providing a definition for design intent in the limited domain of legacy CAD. We also propose a system that uses the definition of design intent in legacy CAD, the idea of context and an inference-oriented approach to classify CAD entities and capture design intent from legacy CAD.

I have been using computers to help artists since the mid 1990s. My first collaboration was with wood sculptor Brent Collins, living in Gower, MO. It was prompted in 1994 by a picture of a small wood sculpture called "Hyperbolic Hexagon" (Fig. 1a) [2]. The loop of six holes and saddles is reminiscent of the central portion of Scherk's "2 nd Minimal Surface." This correspondence led to an interesting discussion and inspired us to explore what shapes might result, if this paradigm was extended to toroidal rings with a different number of holes, to higher order saddles, or to structures in which the hole-saddle chain was subjected to some longitudinal twist before it is closed into the toroidal loop.