Similarity test for free-form surfaces in product design: An integrated approach

Three dimensional free-form surfaces, widely used in CAD/CAM systems, allow users to design and manufacture 3D objects of greater complexity. An integrated approach is proposed to find the level of similarity given two free-form surfaces with substructures. First, the Gaussian curvature values of each surface are mapped into the two-dimensional space, and a shape-based measure is obtained using statistical methods to represent the level of similarity. Second, the comparison of substructures provides additional information about shape and topology, and assists in improving the shape-based measure iteratively. This approach can be applied to surfaces under various transformations, and shows potential associations among surfaces belonging to a single product design, or from different ones. The proposed method can be used to develop data mining techniques for large product databases, and tools for copyright protection of CAD models are expected to evolve.