Martin Guay
Rémi Ronfard
Abstract
We present a space-time abstraction for the sketch-based design of character animation. It allows animators to draft a full coordinated motion using a single stroke called the space-time curve (STC). From the STC we compute a dynamic line of action (DLOA) that drives the motion of a 3D character through projective constraints. Our dynamic models for the line's motion are entirely geometric, require no pre-existing data, and allow full artistic control. The resulting DLOA can be refined by over-sketching strokes along the space-time curve, or by composing another DLOA on top leading to control over complex motions with few strokes. Additionally, the resulting dynamic line of action can be applied to arbitrary body parts or characters. To match a 3D character to the 2D line over time, we introduce a robust matching algorithm based on closed-form solutions, yielding a tight match while allowing squash and stretch of the character's skeleton. Our experiments show that space-time sketching has the potential of bringing animation design within the reach of beginners while saving time for skilled artists.
Supplemental Material
Available for Download
Supplemental files
- Alexa, M., Cohen-Or, D., and Levin, D. 2000. As-rigid-as-possible shape interpolation. In Proceedings of the 27th Annual Conference on Computer Graphics and Interactive Techniques, SIGGRAPH '00, 157--164. Google Scholar
Digital Library
- Burtnyk, N., and Wein, M. 1976. Interactive skeleton techniques for enhancing motion dynamics in key frame animation. Commun. ACM 19, 10, 564--569. Google ScholarDigital Library
- Davis, J., Igarashi, M., Chuang, E., Popovic', Z., and Salesin, D. 2003. A sketching interface for articulated figure animation. Proceedings of the 2003 ACM SIGGRAPH/Eurographics symposium on Computer animation, 320--328. Google ScholarDigital Library
- Davis, R. C., Colwell, B., and Landay, J. A. 2008. K-sketch: A 'kinetic' sketch pad for novice animators. In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, CHI '08, 413--422. Google ScholarDigital Library
- Dontcheva, M., Yngve, G., and Popović, Z. Layered acting for character animation. ACM Trans. Graph. 22, 3, 409--416. Google ScholarDigital Library
- Gleicher, M. Motion path editing. In Proceedings of the 2001 Symposium on Interactive 3D Graphics, I3D '01, 195--202. Google ScholarDigital Library
- Guay, M., Cani, M.-P., and Ronfard, R. 2013. The line of action: An intuitive interface for expressive character posing. ACM Trans. Graph. 32, 6, 205:1--205:8. Google ScholarDigital Library
- Guay, M., Ronfard, R., Gleicher, M., and Cani, M.-P. 2015. Adding dynamics to sketch-based character animations. In proceedings of the Symposium on Sketch-Based Interfaces and Modeling, SBIM '15. Google ScholarDigital Library
- Hodgins, J. K., Wooten, W. L., Brogan, D. C., and O'Brien, J. F. 1995. Animating human athletics. In Proceedings of the 22Nd Annual Conference on Computer Graphics and Interactive Techniques, SIGGRAPH '95, 71--78. Google ScholarDigital Library
- Igarashi, T., Kadobayashi, R., Mase, K., and Tanaka, H. 1998. Path drawing for 3d walkthrough. In Proceedings of the 11th Annual ACM Symposium on User Interface Software and Technology, UIST '98, 173--174. Google ScholarDigital Library
- Kho, Y., and Garland, M. 2005. Sketching mesh deformations. In Proceedings of the 2005 Symposium on Interactive 3D Graphics and Games, I3D '05, 147--154. Google ScholarDigital Library
- Laszlo, J., van de Panne, M., and Fiume, E. 2000. Interactive control for physically-based animation. In Proceedings of the 27th Annual Conference on Computer Graphics and Interactive Techniques, SIGGRAPH '00, 201--208. Google ScholarDigital Library
- Min, J., Chen, Y.-L., and Chai, J. 2009. Interactive generation of human animation with deformable motion models. ACM Trans. Graph. 29, 1, 9:1--9:12. Google ScholarDigital Library
- Neff, M., Albrecht, I., and Seidel, H.-P. 2007. Layered performance animation with correlation maps. Comput. Graph. Forum 26, 3, 675--684.Google ScholarCross Ref
- Öztireli, A. C., Baran, I., Popa, T., Dalstein, B., Sumner, R. W., and Gross, M. 2013. Differential blending for expressive sketch-based posing. In Proceedings of the 2013 ACM SIGGRAPH/Eurographics Symposium on Computer Animation, SCA '13. Google ScholarDigital Library
- Sadasivam, K. M. 2012. Learn to draw dynamic comic characters using the "two cans" technique! Blog post.Google Scholar
- Sederberg, T. W., and Parry, S. R. 1986. Free-form deformation of solid geometric models. In Proceedings of the 13th Annual Conference on Computer Graphics and Interactive Techniques, SIGGRAPH '86, 151--160. Google ScholarDigital Library
- Shiratori, T., Mahler, M., Trezevant, W., and Hodgins, J. K. 2013. Expressing animated performances through puppeteering. IEEE 3DUI, 59--66.Google Scholar
- Thorne, M., Burke, D., and van de Panne, M. 2004. Motion doodles: an interface for sketching character motion. ACM Trans. Graph. 23, 424--431. Google ScholarDigital Library
- Yin, K., Loken, K., and van de Panne, M. 2007. Simbicon: Simple biped locomotion control. ACM Trans. Graph. 26, 3. Google ScholarDigital Library
Index Terms
- Space-time sketching of character animation
Recommendations
Simulating cartoon style animation
NPAR '02: Proceedings of the 2nd international symposium on Non-photorealistic animation and renderingTraditional hand animation is in many cases superior to simulated motion for conveying information about character and events. Much of this superiority comes from an animator's ability to abstract motion and play to human perceptual effects. However, ...
The Squash-and-Stretch Stylization for Character Motions
The squash-and-stretch describes the rigidity of the character. This effect is the most important technique in traditional cartoon animation. In this paper, we introduce a method that applies the squash-and-stretch effect to character motion. Our method ...
Reusing view-dependent animation
In this paper we present techniques for reusing view-dependent animation. First, we provide a framework for representing view-dependent animations. We formulate the concept of a view space, which is the space formed by the key views and their associated ...
Comments