ABSTRACT
Generating highly expressive and caricatured poses can be difficult in 3D computer animation because artists must interact with characters indirectly through complex character rigs. Furthermore, since caricatured poses often involve large bends and twists, artifacts arise with traditional skinning algorithms that are not designed to blend large, disparate rotations and cannot represent extremely large rotations. To overcome these problems, we introduce a differential blending algorithm that can successfully encode and blend large transformations, overcoming the inherent limitation of previous skeletal representations. Based on this blending method, we illustrate a sketch-based interface that supports curved bones and implements the line-of-action concept from hand-drawn animation to create expressive poses in 3D animation. By interpolating stored differential transformations across temporal keyframes, our system also generates caricatured animation. We present a detailed technical analysis of our differential blending algorithm and show several posing and animation results created using our system to demonstrate the utility of our method in practice.
Supplemental Material
- Akeo, M., Hashimoto, H., Kobayashi, T., and Shibusawa, T. 1994. Computer graphics system for reproducing three-dimensional shape from idea sketch. Computer Graphics Forum 13, 3, 477--488.Google ScholarCross Ref
- Alexa, M. 2002. Linear combination of transformations. ACM Trans. Graph. 21, 3 (July), 380--387. Google ScholarDigital Library
- Baran, I., and Popović, J. 2007. Automatic rigging and animation of 3D characters. ACM Trans. Graph. 26, 3 (July), 72:1--72:8. Google ScholarDigital Library
- Baran, I., Lehtinen, J., and Popović, J. 2010. Sketching clothoid splines using shortest paths. Computer Graphics Forum 29, 2 (May), 655--664.Google ScholarCross Ref
- Blair, P. 1994. Cartoon Animation. Walter Foster Publishing.Google Scholar
- Davis, J., Agrawala, M., Chuang, E., Popović, Z., and Salesin, D. 2007. A sketching interface for articulated figure animation. In ACM SIGGRAPH 2007 courses, ACM, New York, NY, USA, SIGGRAPH '07. Google ScholarDigital Library
- Forstmann, S., and Ohya, J. 2006. Fast skeletal animation by skinned arc-spline based deformation. In Proc. Eurographics 2006 Short-Papers, 1--4.Google Scholar
- Forstmann, S., Ohya, J., Krohn-Grimberghe, A., and McDougall, R. 2007. Deformation styles for spline-based skeletal animation. In Proc. SCA '07, Eurographics Association, Aire-la-Ville, Switzerland, Switzerland, 141--150. Google ScholarDigital Library
- Gingold, Y., Igarashi, T., and Zorin, D. 2009. Structured annotations for 2d-to-3d modeling. ACM Trans. Graph. 28 (December), 148:1--148:9. Google ScholarDigital Library
- Govindu, V. 2004. Lie-algebraic averaging for globally consistent motion estimation. In Proc. CVPR 2004, vol. 1, I--684 -- I--691 Vol.1.Google ScholarCross Ref
- Hoshino, J., and Hoshino, Y. 2001. Intelligent storyboard for prototyping animation. Multimedia and Expo, IEEE International Conference on 0, 96.Google Scholar
- Igarashi, T., Matsuoka, S., and Tanaka, H. 1999. Teddy: a sketching interface for 3d freeform design. In Proc. SIGGRAPH '99, ACM Press/Addison-Wesley Publishing Co., New York, NY, USA, 409--416. Google ScholarDigital Library
- Jacobson, A., and Sorkine, O. 2011. Stretchable and twistable bones for skeletal shape deformation. In Proc. SIGGRAPH Asia 2011, ACM, New York, NY, USA, SA '11, 165:1--165:8. Google ScholarDigital Library
- Kavan, L., and Žára, J. 2005. Spherical blend skinning: a realtime deformation of articulated models. In Proc. I3D '05, ACM, New York, NY, USA, 9--16. Google ScholarDigital Library
- Kavan, L., Collins, S., Zara, J., and O'Sullivan, C. 2008. Geometric skinning with approximate dual quaternion blending. ACM Trans. Graph. 27, 4, 105:1--105:23. Google ScholarDigital Library
- Kho, Y., and Garland, M. 2005. Sketching mesh deformations. In Proc. I3D '05, ACM, New York, NY, USA, 147--154. Google ScholarDigital Library
- Kraevoy, V., Sheffer, A., and van de Panne, M. 2009. Modeling from contour drawings. In Proc. SBIM '09, ACM, New York, NY, USA, 37--44. Google ScholarDigital Library
- Magnenat-Thalmann, N., Laperrière, R., and Thalmann, D. 1988. Joint-dependent local deformations for hand animation and object grasping. In Proc. Graphics interface '88, Canadian Information Processing Society, Toronto, Ont., Canada, Canada, 26--33. Google ScholarDigital Library
- Mao, C., Qin, S., and Wright, D. 2005. A sketch-based gesture interface for rough 3d stick figure animation. In Proc. SBIM. Dublin, 2005, Eurographics.Google Scholar
- Mao, C., Qin, S., and Wright, D. 2007. Sketch-based virtual human modelling and animation. In Smart Graphics, A. Butz, B. Fisher, A. Krüger, P. Olivier, and S. Owada, Eds., vol. 4569 of Lecture Notes in Computer Science. Springer Berlin/Heidelberg, 220--223. Google ScholarDigital Library
- Mao, C., Qin, S. F., and Wright, D. 2009. A sketch-based approach to human body modelling. Computers & Graphics 33, 4, 521--541. Google ScholarDigital Library
- Mohr, A., and Gleicher, M. 2003. Building efficient, accurate character skins from examples. In Proc. ACM SIGGRAPH 2003, ACM, New York, NY, USA, SIGGRAPH '03, 562--568. Google ScholarDigital Library
- Nealen, A., Sorkine, O., Alexa, M., and Cohen-Or, D. 2005. A sketch-based interface for detail-preserving mesh editing. ACM Trans. Graph. 24, 3 (July), 1142--1147. Google ScholarDigital Library
- Nealen, A., Igarashi, T., Sorkine, O., and Alexa, M. 2007. Fibermesh: designing freeform surfaces with 3d curves. ACM Trans. Graph. 26, 3 (July). Google ScholarDigital Library
- Olsen, L., Samavati, F., Sousa, M., and Jorge, J. 2008. A taxonomy of modeling techniques using sketch-based interfaces. In Proc. Eurographics 2008, STAR.Google Scholar
- Thorne, M., Burke, D., and van de Panne, M. 2004. Motion doodles: an interface for sketching character motion. ACM Trans. Graph. 23, 3 (Aug.), 424--431. Google ScholarDigital Library
- Whitaker, H., and Halas, J. 2002. Timing for Animation. Focal Press.Google Scholar
- Yang, X., Somasekharan, A., and Zhang, J. J. 2006. Curve skeleton skinning for human and creature characters: Research articles. Comput. Animat. Virtual Worlds 17, 3-4 (July), 281--292. Google ScholarDigital Library
- Zeleznik, R. C., Herndon, K. P., and Hughes, J. F. 1996. Sketch: An interface for sketching 3d scenes. In Computer Graphics, Proc. Siggraph 1996, 163--170. Google ScholarDigital Library
- Zhou, K., Huang, J., Snyder, J., Liu, X., Bao, H., Guo, B., and Shum, H.-Y. 2005. Large mesh deformation using the volumetric graph laplacian. ACM Trans. Graph. 24, 3 (July), 496--503. Google ScholarDigital Library
- Zimmermann, J., Nealen, A., and Alexa, M. 2008. Sketch-based interfaces: Sketching contours. Comput. Graph. 32, 5 (Oct.), 486--499. Google ScholarDigital Library
Index Terms
- Differential blending for expressive sketch-based posing
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