An Approach to Indexing Databases of Solid Models

Computer-Aided Designs and Solid Models are a media of immense importance across a wide spectrum of engineering design and manufacturing disciplines. Computer-Aided Design (CAD) data and the engineers who use it, have unique data access constraints and requirements. Previous work from multimedia databases has developed a repertoire of technologies for similarly-based and semantic indexing conventional multimedia data (e.g., images, video, audio). While great strides in management of conventional media, little work exists on how to perform contentbased indexing, clustering and mining of engineering data, CAD data and solid models. This paper presents our approach and preliminary experimental results toward a general indexing scheme for solid models of mechanical designs. To achieve this, we create a mapping of solid model boundary representations and engineering attributes into Model Signature Graphs. We employ spectral graph theoretic techniques to project the model signature graphs into Model Comparison Spaces—high-dimensional vector spaces which can be used to compute metric distances among CAD models. These distance measures, called EigenDistances, are used to create a spatial index of the model comparison space using an -tree data structure. We develop heuristics that exploit properties of the model comparison space to ensure that the -tree indexes remain balanced. In order to validate our approach, we applied this methodology to the contents of the National Design Repository (http://www.designrepository.org). The National Design Repository is a large public collection of over 55,000 solid models from a variety of real-world Computer-Aided Design domains. First, we assess the quality of the EigenDistance measure in pairwise comparison of solid models. Second, we evaluate the -tree indexes with a sampling of range queries using real industrial CAD data. Our implementation testbed is based on the PostgreSQL RDBMS. We believe that this work is of significance to both the database and engineering communities: we provide a novel approach to manage a unique media type and answer queries of practical importance to engineering design and manufacturing enterprises.