Surface shape-based clustering for B-rep models
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Surface shape-based clustering for B-rep models Jihua Wang 1 & Wei Yan 1 & Chao Huang 1 Received: 17 May 2019 / Revised: 11 May 2020 / Accepted: 24 June 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
Matching, clustering, and retrieving 3D CAD models of mechanical components based on their shape are useful for many CAD/CAM applications such as design reuse, variant process planning and group technology. Surfaces are the prominent elements of the BRep (Boundary Representation) CAD model, but the current methods of similarity assessment are not centered on the surfaces and lack an accurate description of their geometric features. In order to solve the problem of retrieval and clustering of B-Rep models more efficiently, the concept of “most crucial surface” is proposed and its corresponding characteristics are studied in detail. The contribution of our approach is that surfaces are the major shape determinants of the B-Rep model, and the distribution of Carosati curvatures is the optimum shape features of surfaces. First, the surface elements are extracted from the STEP (Standard for Exchange of Product Model) files of the B-rep models, and the distribution of minimum, Gauss and Carosati surface curvatures are converted into the shape feature space by the wavelet transform, the Fourier transform, and the grouping calculation. Thus we characterize the B-Rep model as a histogram with surfaces as bins, and then compare and cluster the B-Rep models by the bipartite matching algorithm or the earth mover’s distance. The surface-based methods are evaluated with the four effectiveness indices in the clustering experiment of the NDR (National Design Reservoir) data, and the results indicated that the grouping method for the surface Carosati curvatures has a highly competent matching and clustering performance. Keywords Surface shape . B-rep model . Surface curvature . 3D model clustering . STEP(standard for exchange of product model) . Bipartite graph matching . Earth mover’s distance
* Wei Yan [email protected] Jihua Wang [email protected] Chao Huang [email protected] Extended author information available on the last page of the article
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1 Introduction Matching, clustering, and retrieving 3D CAD models of mechanical components based on their shape are useful for many CAD/CAM applications such as design reuse, variant process planning and group technology in the fields of industrial design and manufacture. The B-Rep model is almost the only representation way of 3D CAD models related to industrial objects or artifacts, and it widely adopts the STEP format in data sharing and exchange, so STEP file should be unique for a single component regardless of the underlying CAD system [5]. The STEP files provide us with an unambiguous scheme to completely contain geometric and topological information of the B-Rep model, which is a hierarchy of geometric and topological elements such as solids, shells, surfaces, loops and edges. In the process of design reuse or g
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