Physically based rigging for deformable characters

ABSTRACT

In this paper we introduce a framework for instrumenting ("rigging") characters that are modeled as dynamic elastic bodies, so that their shapes can be controlled by an animator. Because the shape of such a character is determined by physical dynamics, the rigging system cannot simply dictate the shape as in traditional animation. For this reason, we introduce forces as the building blocks of rigging. Rigging forces guide the shape of the character, but are combined with other forces during simulation. Forces have other desirable features: they can be combined easily and simulated at any resolution, and since they are not tightly coupled with the surface geometry, they can be more easily transferred from one model to another. Our framework includes a new pose-dependent linearization scheme for elastic dynamics, which ensures a correspondence between forces and deformations, and at the same time produces plausible results at interactive speeds. We also introduce a novel method of handling collisions around creases.

REFERENCES

• 1: {AB03} Ascher U. M., Boxerman E.: On the modified conjugate gradient method in cloth simulation. Visual Computer 19, 7--8 (2003), 526--531.
• 2: Brett Allen , Brian Curless , Zoran Popović, Articulated body deformation from range scan data, ACM Transactions on Graphics (TOG), v.21 n.3, July 2002
• 3: Marc Alexa, Linear combination of transformations, ACM Transactions on Graphics (TOG), v.21 n.3, July 2002
• 4: {AT01} Aubel A., Thalmann D.: Interactive modeling of the human musculature. In Proceedings of Computer Animation 2001 (2001).
• 5: Richard H. Byrd , Peihuang Lu , Jorge Nocedal , Ciyou Zhu, A limited memory algorithm for bound constrained optimization, SIAM Journal on Scientific Computing, v.16 n.5, p.1190-1208, Sept. 1995 [doi>10.1137/0916069]
• 6: Paul J. Besl , Neil D. McKay, A Method for Registration of 3-D Shapes, IEEE Transactions on Pattern Analysis and Machine Intelligence, v.14 n.2, p.239-256, February 1992 [doi>10.1109/34.121791]
• 7: David Baraff , Andrew Witkin, Dynamic simulation of non-penetrating flexible bodies, Proceedings of the 19th annual conference on Computer graphics and interactive techniques, p.303-308, July 1992
• 8: David Baraff , Andrew Witkin, Large steps in cloth simulation, Proceedings of the 25th annual conference on Computer graphics and interactive techniques, p.43-54, July 1998 [doi>10.1145/280814.280821]
• 9: Steve Capell , Brian Curless , Zoran Popovic, Interactive character animation using dynamic elastic simulation, 2004
• 10: Steve Capell , Seth Green , Brian Curless , Tom Duchamp , Zoran Popović, Interactive skeleton-driven dynamic deformations, ACM Transactions on Graphics (TOG), v.21 n.3, July 2002
• 11: Gilles Debunne , Mathieu Desbrun , Marie-Paule Cani , Alan H. Barr, Dynamic real-time deformations using space & time adaptive sampling, Proceedings of the 28th annual conference on Computer graphics and interactive techniques, p.31-36, August 2001 [doi>10.1145/383259.383262]
• 12: G. Irving , J. Teran , R. Fedkiw, Invertible finite elements for robust simulation of large deformation, Proceedings of the 2004 ACM SIGGRAPH/Eurographics symposium on Computer animation, August 27-29, 2004, Grenoble, France [doi>10.1145/1028523.1028541]
• 13: Doug L. James , Dinesh K. Pai, DyRT: dynamic response textures for real time deformation simulation with graphics hardware, Proceedings of the 29th annual conference on Computer graphics and interactive techniques, July 23-26, 2002, San Antonio, Texas
• 14: Paul G. Kry , Doug L. James , Dinesh K. Pai, EigenSkin: real time large deformation character skinning in hardware, Proceedings of the 2002 ACM SIGGRAPH/Eurographics symposium on Computer animation, July 21-22, 2002, San Antonio, Texas [doi>10.1145/545261.545286]
• 15: J. P. Lewis , Matt Cordner , Nickson Fong, Pose space deformation: a unified approach to shape interpolation and skeleton-driven deformation, Proceedings of the 27th annual conference on Computer graphics and interactive techniques, p.165-172, July 2000 [doi>10.1145/344779.344862]
• 16: Matthias Müller , Julie Dorsey , Leonard McMillan , Robert Jagnow , Barbara Cutler, Stable real-time deformations, Proceedings of the 2002 ACM SIGGRAPH/Eurographics symposium on Computer animation, July 21-22, 2002, San Antonio, Texas [doi>10.1145/545261.545269]
• 17: Alex Mohr , Michael Gleicher, Building efficient, accurate character skins from examples, ACM Transactions on Graphics (TOG), v.22 n.3, July 2003
• 18: Matthias Müller , Markus Gross, Interactive virtual materials, Proceedings of the 2004 conference on Graphics interface, p.239-246, May 17-19, 2004, London, Ontario, Canada
• 19: Ron MacCracken , Kenneth I. Joy, Free-form deformations with lattices of arbitrary topology, Proceedings of the 23rd annual conference on Computer graphics and interactive techniques, p.181-188, August 1996 [doi>10.1145/237170.237247]
• 20: John C. Platt , Alan H. Barr, Constraints methods for flexible models, Proceedings of the 15th annual conference on Computer graphics and interactive techniques, p.279-288, June 1988
• 21: Mark Pauly , Dinesh K. Pai , Leonidas J. Guibas, Quasi-rigid objects in contact, Proceedings of the 2004 ACM SIGGRAPH/Eurographics symposium on Computer animation, August 27-29, 2004, Grenoble, France [doi>10.1145/1028523.1028539]
• 22: Laks Raghupathi , Laurent Grisoni , Francois Faure , Damien Marchal , Marie-Paule Cani , Christophe Chaillou, An Intestinal Surgery Simulator: Real-Time Collision Processing and Visualization, IEEE Transactions on Visualization and Computer Graphics, v.10 n.6, p.708-718, November 2004 [doi>10.1109/TVCG.2004.36]
• 23: Karan Singh , Eugene Fiume, Wires: a geometric deformation technique, Proceedings of the 25th annual conference on Computer graphics and interactive techniques, p.405-414, July 1998 [doi>10.1145/280814.280946]
• 24: Peter-Pike J. Sloan , Charles F. Rose, III , Michael F. Cohen, Shape by example, Proceedings of the 2001 symposium on Interactive 3D graphics, p.135-143, March 2001 [doi>10.1145/364338.364382]
• 25: K. Singh , J. Ohya , R. Parent, Human figure synthesis and animation for virtual space teleconferencing, Proceedings of the Virtual Reality Annual International Symposium (VRAIS'95), p.118, March 11-15, 1995
• 26: Thomas W. Sederberg , Scott R. Parry, Free-form deformation of solid geometric models, ACM SIGGRAPH Computer Graphics, v.20 n.4, p.151-160, Aug. 1986
• 27: Ferdi Scheepers , Richard E. Parent , Wayne E. Carlson , Stephen F. May, Anatomy-based modeling of the human musculature, Proceedings of the 24th annual conference on Computer graphics and interactive techniques, p.163-172, August 1997 [doi>10.1145/258734.258827]
• 28: Demetri Terzopoulos , John Platt , Alan Barr , Kurt Fleischer, Elastically deformable models, Proceedings of the 14th annual conference on Computer graphics and interactive techniques, p.205-214, August 1987
• 29: Demetri Terzopoulos , Andrew Witkin, Physically Based Models with Rigid and Deformable Components, IEEE Computer Graphics and Applications, v.8 n.6, p.41-51, November 1988 [doi>10.1109/38.20317]
• 30: Jane Wilhelms , Allen Van Gelder, Anatomically based modeling, Proceedings of the 24th annual conference on Computer graphics and interactive techniques, p.173-180, August 1997 [doi>10.1145/258734.258833]
• 31: Andrew Witkin , William Welch, Fast animation and control of nonrigid structures, Proceedings of the 17th annual conference on Computer graphics and interactive techniques, p.243-252, September 1990, Dallas, TX, USA [doi>10.1145/97879.565650]