In certain shape similarity assessment applications, type, locations, and orientations of faces in boundary representations plays a key role in determining similarity between two parts. This paper describes an algorithm that assesses similarity between two parts by explicitly aligning their faces and hence accounts for these face attributes. The approach involves extracting attributed applied vectors from the face information of parts and aligning the two sets of attributed applied vectors using rigid body transformations. The algorithm uses a customizable distance function to align attributed applied vectors. The distance between two aligned attributed applied vector sets is used as a measure of similarity between two parts. This paper also presents computational results to illustrate discrimination capability of the algorithm.Keywords: Shape similarity assessment, alignment of models, and design reuse.
INTRODUCTIONOver the last fifteen years 3D CAD systems have become very popular in the industry. These CAD systems are being used to generate 3D models of parts. Nowadays, organizations routinely set up databases of CAD models to enable all participants in the product development process to have access to 3D data to support their functions. CAD databases for even moderate size companies are expected to be large in size. Intuitively, if two products are similar, it is possible to reuse information about one product to derive corresponding information about the other one. There are many possible applications where reuse of information can be of significant value. Representative examples include part-family formation, redesign suggestion generation, supplier selection, cost estimation, tooling design, machine selection, stock selection, and design reuse. The ability to search for similar products in a database by specifying a query product is expected to help companies in significantly reducing the associated time and cost compared with the manual methods of locating the similar products. In [12] an overview on contentbased search techniques for parts and assemblies is given. In certain applications, locations, type, and orientations of faces play a major role in determining similarity between two parts. For example, similarity between two molded parts from the tool maker selection point of view needs to be assessed by analyzing characteristics of part faces. For example, face parameters such as spatial location, type and curvature distribution determine the type and complexity of the tooling needed to manufacture the part. Similarly, the face area determines the size of the tooling. Face features do not always have explicitly defined parameters. Hence we need to identify components of face feature vectors that are significant in determining the similarity between two parts from the tooling point of view. Shape similarity assessment problem has been studied extensively in literature. We have presented a survey in [2]. Representative techniques include shape histogram-based techniques [9,13,18,21], graph-bas...