Automatic rigging for animation characters with 3D silhouette

Animating an articulated 3D character requires the specification of its interior skeleton structure which defines how the skin surface is deformed during animation. Currently this task is to a large extent accomplished manually, which consumes a large amount of animators' time. This paper presents an automatic rigging method making use of a new geometry entity called the 3D silhouette. The first step is to extract a coarse 3D curve skeleton and some skeletal joints of a character. This curve skeleton is then refined with a perpendicular silhouette. According to the connectivity of the skeletal joints, the hierarchical animation skeleton is finally constructed. By avoiding complicated computation such as voxelization and pruning, this method is simple and efficient, much faster than existing methods. It proves very useful for quick animation production, with applications including games design and prototype graphical systems. Copyright © 2009 John Wiley & Sons, Ltd. Generating animation skeleton of a hand model with our method: (a) Original mode, (b) Primary 3D silhouette, (c) 3D medial axis of hand through constrained Delaunay triangulation, (d) Decomposition result, (e) Curve skeleton and key skeleton points, (f) Animation skeleton.

[1]  Tamal K. Dey,et al.  Defining and computing curve-skeletons with medial geodesic function , 2006, SGP '06.

[2]  Thomas A. Funkhouser,et al.  The Princeton Shape Benchmark , 2004, Proceedings Shape Modeling Applications, 2004..

[3]  Richard E. Parent,et al.  Automated generation of control skeletons for use in animation , 2002, The Visual Computer.

[4]  Wan-Chun Ma,et al.  Domain connected graph: the skeleton of a closed 3D shape for animation , 2006, The Visual Computer.

[5]  Deborah Silver,et al.  Curve-Skeleton Properties, Applications, and Algorithms , 2007, IEEE Transactions on Visualization and Computer Graphics.

[6]  Arthur W. Toga,et al.  Efficient Skeletonization of Volumetric Objects , 1999, IEEE Trans. Vis. Comput. Graph..

[7]  Ray A. Jarvis,et al.  On the Identification of the Convex Hull of a Finite Set of Points in the Plane , 1973, Inf. Process. Lett..

[8]  Scott Schaefer,et al.  Example-based skeleton extraction , 2007, Symposium on Geometry Processing.

[9]  Tong-Yee Lee,et al.  Skeleton extraction by mesh contraction , 2008, SIGGRAPH 2008.

[10]  Christine Depraz,et al.  Harmonic skeleton for realistic character animation , 2007, SCA '07.

[11]  Tong-Yee Lee,et al.  Curve-Skeleton Extraction Using Iterative Least Squares Optimization , 2008, IEEE Transactions on Visualization and Computer Graphics.

[12]  Wan-Chun Ma,et al.  Automatic Animation Skeleton Construction Using Repulsive Force Field , 2003 .

[13]  J. Tierny,et al.  3D Mesh Skeleton Extraction Using Topological and Geometrical Analyses , 2006 .

[14]  Yee-Hong Yang,et al.  Skeletonisation: An electrostatic field-based approach , 1998, Pattern Analysis and Applications.

[15]  Ilya Baran,et al.  Automatic rigging and animation of 3D characters , 2007, SIGGRAPH 2007.

[16]  Doug L. James,et al.  Skinning mesh animations , 2005, SIGGRAPH 2005.

[17]  Aly A. Farag,et al.  Robust centerline extraction framework using level sets , 2005, 2005 IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR'05).

[18]  Ayellet Tal,et al.  Mesh segmentation using feature point and core extraction , 2005, The Visual Computer.