Skeleton Extraction of 3D Objects by Radial Basis Functions for Content-based Retrieval in MPEG-7 Ming Ouhyoung Fu-Che Wu, Wan-Chun Ma, Communication and Multimedia Lab Dept. of Computer Science and Information Engineering, National Taiwan University

Previous Collaboration: MPEG-4 Based French Driven Talking Head and Lip Motion Analysis Realistic 3D Facial Animation Parameters from Mirror-Reflected Multi-view Video MPEG-4 Based Demo of the above ( ananova, anim2, track )

MPEG-4 to MPEG-7 Transition A New 3 Year Collaborative Project in Multimedia Lab, National Taiwan University Skeleton Extraction of 3D Objects for Content-based Retrieval in MPEG-7

Search results Similarity Target model 3D Object Retrieval 445 3D obejcts

Part 1: 3D Object Retrieval For each vertex of the object, calculate a sum of the geodesic distance from this vertex to others Get a Reeb graph, where each node represents a region according to the value The similarity of two objects is calculated using area and length of the node of their Reeb graph

Previous Work Masaki Hilaga, Yoshihisa Shinagawa, Taku Kohmura and Tosiyasu L. Kunii, “Topology Matching for Fully Automatic Similarity Estimation of 3D Shapes”, Proceedings of ACM SIGGRAPH, Robert Osada, Thomas Funkhouser, Bernard Chazelle and David Dobkin “Matching 3D Models with Shape Distributions”, Proceedings of Workshop on Shape- Based Retrieval and Analysis of 3D Models, Princeton, USA, Oct

Previous Work Christopher M. Cyr and Benjamin B. Kimia, “3D Object Recognition Using Shape Similiarity-Based Aspect Graph”, Michael Elad, Ayellet Tal and Sigal Ar, “Content Based Retrieval of VRML Objects – A Iterative and Interactive Approach”, 2001

Using a skeletal structure of a 3D shape as a search key Reeb graph –Always consists of a one-dimensional graph structure –Invariant to translation, rotation and scaling –Robust against connectivity changes caused by simplification, subdivision and remesh –Resistant against noise and certain changes due to deformation –Introduce a multiresolutional structure

Geodesic distance The distance from point to point on a surface (the length of shortest path) Lazarus et al. proposed a level set diagram (LSD) structure in which geodesic distance from a source point is used as the function µ

3D Object Retrieval The approach represents the skeletal and topological structure of a 3D object Search 3D object automatically and quickly Robust against translation, rotation, scaling, simplification, subdivision, noise, deformation Demo – –445 objects in the database –0.08 sec for comparing two objects on the average

Search results Similarity Target model 3D Object Retrieval 445 3D obejcts

Skeletal Representation by Radial Basis Function Improvements over Multi-resolution Reeb Graph: not exactly a skeleton of mesh models How about Medial Axis Transformation Representation? Skip to part 2 slides