3D shape-based retrieval within the MPEG-7 framework

Because of the continuous development of multimedia technologies, virtual worlds and augmented reality, 3D contents become a common feature of the today information systems. Hence, standardizing tools for content-based indexing of visual data is a key issue for computer vision related applications. Within the framework of the future MPEG-7 standard, tools for intelligent content-based access to 3D information, targeting applications such as search & retrieval and browsing of 3D model databases, have been recently considered and evaluated. In this paper, we present the 3D Shape Spectrum Descriptor (3D SSD), recently adopted within the current MPEG-7 Committee Draft (CD). The proposed descriptor aims at providing an intrinsic shape description of a 3D mesh and is defined as the distribution of the shape index over the entire mesh. The shape index is a local geometric attribute of a 3D surface, expressed as the angular coordinate of a polar representation of the principal curvature vector. Experimental results have been carried out upon the MPEG-7 3D model database consisting of about 1300 meshes in VRML 2.0 format. Objective retrieval results, based upon the definition of a ground truth subset, are reported in terms of Bull Eye Percentage (BEP) score.