Journal of the Korea Computer Graphics Society (한국컴퓨터그래픽스학회논문지)

Korea Computer Graphics Society (한국컴퓨터그래픽스학회)
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Body Motion Retargeting to Rig-space

리깅 공간으로의 몸체 동작 리타겟팅

  • Received : 2014.07.04
  • Accepted : 2014.08.20
  • Published : 2014.09.01
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Abstract

This paper presents a method to retarget a source motion to the rig-space parameter for a target character that can be equipped with a complex rig structure as used in traditional animation pipelines. Our solution allows the animators to edit the retargeted motion easily and intuitively as they can work with the same rig parameters that have been used for keyframe animation. To acheive this, we analyze the correspondence between the source motion space and the target rig-space, followed by performing non-linear optimization for the motion retargeting to target rig-space. We observed the general workflow practiced by animators and apply this process to the optimization step.

본 논문에서는 대상이 되는 디지털 캐릭터가 기존 애니메이션 파이프라인에서 사용되는 수준의 복잡한 리깅을 가졌더라도, 해당 리깅의 리깅 공간(Rig-space)에 모션을 리타겟팅 할 수 있는 안정적이고 새로운 리타게팅 방법을 활용한다. 이를 위하여 다양하고 복잡한 방식으로 리깅된 서로 다른 캐릭터의 리깅 공간과 캐릭터 관절값 공간(Joint Parameter Space)간의 상관관계를 분석하고, 원본 모션을 최대한 보존하면서 효율적으로 리타게팅을 수행할 수 있는 비선형적 최적화 기법을 제안한다. 이로 인하여 애니메이터는 모션 캡쳐 등으로 얻어진 원본 모션을 수정할 때, 기존의 키프레이밍 작업과 동일한 리깅 파라미터를 사용할 수 있게 되어 직관적이면서도 빠르고 쉽게 모션을 수정할 수 있게 된다. 이 과정에서 애니메이터가 선호하는 작업 방식을 관찰한 후, 해당 과정을 최적화 과정에 반영함으로써 애니메이터가 수정하기에 매우 용이한 형태의 리타겟팅 결과물을 만들어 낼 수 있다.

Keywords

References

  1. T. McLaughlin, L. Cutler, and D. Coleman, "Character rigging, deformations, and simulations in film and game production," in ACM SIGGRAPH 2011 Courses, ser. SIGGRAPH '11. New York, NY, USA: ACM, 2011, pp. 5:1-5:18. [Online]. Available: http://doi.acm.org/10.1145/2037636.2037641
  2. M. Gleicher, "Retargetting motion to new characters," in Proceedings of the 25th Annual Conference on Computer Graphics and Interactive Techniques, ser. SIGGRAPH '98. New York, NY, USA: ACM, 1998, pp. 33-42. [Online]. Available: http://doi.acm.org/10.1145/280814.280820
  3. K. jin Choi and H. seok Ko, "On-line motion retargetting," Journal of Visualization and Computer Animation, vol. 11, pp. 223-235, 1999.
  4. C. Hecker, B. Raabe, R. W. Enslow, J. DeWeese, J. Maynard, and K. van Prooijen, "Real-time motion retargeting to highly varied user-created morphologies," in ACM SIGGRAPH 2008 Papers, ser. SIGGRAPH '08. New York, NY, USA: ACM, 2008, pp. 27:1-27:11. [Online]. Available: http://doi.acm.org/10.1145/1399504.1360626
  5. K. Grochow, S. L. Martin, A. Hertzmann, and Z. Popovi´c, "Style-based inverse kinematics," in ACM SIGGRAPH 2004 Papers, ser. SIGGRAPH '04. New York, NY, USA: ACM, 2004, pp. 522-531. [Online]. Available: http://doi.acm.org/10.1145/1186562.1015755
  6. E. Hsu, M. da Silva, and J. Popovi´c, "Guided time warping for motion editing," in Proceedings of the 2007 ACM SIGGRAPH/ Eurographics Symposium on Computer Animation, ser. SCA '07. Aire-la-Ville, Switzerland, Switzerland: Eurographics Association, 2007, pp. 45-52. [Online]. Available: http://dl.acm.org/citation.cfm?id=1272690.1272697
  7. J. Min, H. Liu, and J. Chai, "Synthesis and editing of personalized stylistic human motion," in Proceedings of the 2010 ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games, ser. I3D '10. New York, NY, USA: ACM, 2010, pp. 39-46. [Online]. Available: http://doi.acm.org/10.1145/1730804.1730811
  8. C. K. Liu, A. Hertzmann, and Z. Popovi´c, "Learning physicsbased motion style with nonlinear inverse optimization," in ACM SIGGRAPH 2005 Papers, ser. SIGGRAPH '05. New York, NY, USA: ACM, 2005, pp. 1071-1081. [Online]. Available: http://doi.acm.org/10.1145/1186822.1073314
  9. X. Wei, J. Min, and J. Chai, "Physically valid statistical models for human motion generation," ACM Trans. Graph., vol. 30, no. 3, pp. 19:1-19:10, May 2011. [Online]. Available: http://doi.acm.org/10.1145/1966394.1966398
  10. P. Naas, Autodesk Maya 2014 Essentials: Autodesk Official Press, 1st ed. Alameda, CA, USA: SYBEX Inc., 2013.
  11. F. Hahn, S. Martin, B. Thomaszewski, R. Sumner, S. Coros, and M. Gross, "Rig-space physics," ACM Trans. Graph., vol. 31, no. 4, pp. 72:1-72:8, July 2012. [Online]. Available: http://doi.acm.org/10.1145/2185520.2185568
  12. F. Hahn, B. Thomaszewski, S. Coros, R. W. Sumner, and M. Gross, "Efficient simulation of secondary motion in rig-space," in Proceedings of the 12th ACM SIGGRAPH/Eurographics Symposium on Computer Animation, ser. SCA '13. New York, NY, USA: ACM, 2013, pp. 165-171. [Online]. Available: http://doi.acm.org/10.1145/2485895.2485918
  13. S. G. Johnson, The NLopt nonlinear-optimization package, 2011. [Online]. Available: http://ab-initio.mit.edu/nlopt
  14. M. J. D. Powell, "The BOBYQA algorithm for bound constrained optimization without derivatives," Department of Applied Mathematics and Theoretical Physics, Cambridge, England, Technical Report NA2009/06, 2009.
  15. J. A. Nelder and R. Mead, "A simplex method for function minimization," Computer Journal, vol. 7, pp. 308-313, 1965. https://doi.org/10.1093/comjnl/7.4.308