Partial Entity Structure: A Compact Non-Manifold Boundary Representation Based on Partial Topological Entities Sang Hun Lee Kunwoo Lee Graduate School of Automotive Engineering School of Mechanical and Aerospace Engineering Kookmin University, Korea Seoul National University, Korea +82-2-910-4835 +82-2-880-7141 shlee@kookmin,ac.kr
[email protected] ABSTRACT 1. INTRODUCTION Non-manifold boundary representations have gained a great deal As a key element in CAD/CAM applications, geometric modeling of popularity in recent years and various representation schemes systems have evolved to widen their representation domains from have been proposed because they allow an even wider range of wireframes to surfaces, to solids, and finally to non-manifold objects for various applications than conventional manifold objects. Unlike previous geometric modelers, the non-manifold representations. However, since these schemes are mainly modeler allows any combination of wireframe, surface, solid, and interested in describing sufficient adjacency relationships of cellular models to be represented and manipulated in a unified topological entities, the models represented in these schemes topological representation. This characteristic provides many occupy too much storage space redundantly although they are advantages over conventional modelers as follows: very efficient in answering queries on topological adjacency • The non-manifold modeler can provide an integrated relationships. Storage requirement can arise as a crucial problem environment for the product development process, as the non- in models in which topological data is more dominant than manifold topological representation can represent different geometric data, such as tessellated or mesh models. models required in various stages of product development; To solve this problem, in this paper, we propose a compact conceptual design, final design, analysis, and manufacture [5, non-manifold boundary representation, called the partial entity 30].