Journal of KIISE:Computer Systems and Theory (한국정보과학회논문지:시스템및이론)

Korean Institute of Information Scientists and Engineers (한국정보과학회)
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Motion Simplification of Virtual Character

가상 캐릭터의 동작 단순화 기법

  • 안정현 (한국과학기술원 전자전산학과) ;
  • 오승우 (한국과학기술원 전자전산학과) ;
  • 원광연 (한국과학기술원 전자전산학과)
  • Published : 2006.10.15
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Abstract

The level-of-detail (LoD), which is a method of reducing polygons on mesh, is one of the most fundamental techniques in real-time rendering. In this paper, we propose a novel level-of-detail technique applied to the virtual character's motion (Motion LoD). The movement of a virtual character can be defined as the transformation of each joint and it's relation to the mesh. The basic idea of the proposed 'Motion LoD' method is to reduce number of joints in an articulated figure and minimize the error between original and simplified motion. For the motion optimization, we propose an error estimation method and a linear system reconstructed from this error estimation for a fast optimization. The proposed motion simplification method is effectively useful for motion editing and real-time crowd animation.

컴퓨터 그래픽스 분야에 활용되는 단순화 기법(LoD)은 실시간 렌더링을 위해 메쉬(mesh)의 다각형 수를 줄이는 방법으로 널리 알려져 있다. 본 논문에서는 이러한 단순화 기법의 기본적인 개념이 가상 캐릭터의 동작 단순화에 적용된 새로운 방법론을 제안한다. 가상 캐릭터의 구성요소 중 하나인 관절은 동작을 생성하는 기본 단위로서 메쉬와 연계되어 캐릭터의 움직임을 생성한다. 동작 단순화의 기본과정은 이러한 캐릭터의 관절 수를 줄이고 남은 관절들의 움직임을 기존동작과 가장 유사하도록 최적화 하는 방법이다. 동작의 최적화를 위해 기존 동작과 단순화 된 동작 간의 오차를 측정하는 방법론을 제시하고, 최적화 문제를 빠르게 풀기 위해 동작 간 오차 식을 선형시스템으로 재구성한다. 본 논문에 제시한 동작 단순화 방법은 동작편집 또는 군중 애니메이션의 성능향상 둥 캐릭터 애니메이션의 여러 분야에 유용하게 활용 될 수 있다.

Keywords

References

  1. H. Hoppe, 'Progressive Mesh,' ACM SIGGRAPH 96, pp. 99-108, 1996 https://doi.org/10.1145/237170.237216
  2. M. Garland and P. Heckbert. 'Mesh Simplification with Quadric Error Metrics,' ACM SIGGRAPH 97, pp.209-216, 1997
  3. H. Kim and K. Wohn, 'Multiresolution Model Generation with Geometry and Texture,' VSMM 2001 https://doi.org/10.1109/VSMM.2001.969745
  4. D. Carlson and J. Hodgins, 'Simulation Levels of Detail for Real-time Animation,' Graphics Interface 97, 1997
  5. J. Ahn and K. Wohn, 'Motion Level-of-Detail: A Simplification Method on Crowd Scene,' CASA 2004
  6. M. Gleicher, 'Retargetting Motion to New Character,' ACM SIGGRAPH 98, pp.33-42, 1998 https://doi.org/10.1145/280814.280820
  7. K. Choi and H. Ko, 'Online Motion Retargetting,' Journal of Visualization and Computer Animation 11 (5): pp. 223-235, 2000 https://doi.org/10.1002/1099-1778(200012)11:5<223::AID-VIS236>3.0.CO;2-5
  8. J. Beaudoin and J. Keyser, 'Simulation Levels of Detail for Plant Motions,' SCA 2004 https://doi.org/10.1145/1028523.1028563
  9. S. Redan, N. Galoppo and M. Lin, 'Adaptive Dynamics of Articulated Bodies,' ACM SIGGRAPH 2005 https://doi.org/10.1145/1187112.1187143
  10. J. Lewis, M. Cordner and N. Fang, 'Pose Space Deformations: A Unified Approach to Shape Interpolation and Skeleton-Driven Deformation,' ACM SIGGRAPH 2000 https://doi.org/10.1145/344779.344862
  11. B. Allen, B. Curless and Z. Popovic, 'Articulated Body Deformation From Range Scan Data,' ACM Transaction on Graphics 21(3): pp.612-619, 2002. https://doi.org/10.1145/566654.566626
  12. X. Wang and C. Phillips, 'Multi-weight Enveloping Least squares Approximation Techniques for Skin Animation,' ACM SIGGRAPH Symposium on Computer Animation, pp.129-138, 2002 https://doi.org/10.1145/545261.545283
  13. D. James and C. Twigg, 'Skinning Mesh Animation,' ACM SIGGRAPH 2005
  14. M. Muller, B. Heidelberger, M. Teschner and M. Gross, 'Mesh less Deformations Based on Shape Matching,' ACM SIGGRAPH 2005
  15. A. Aubel, R. Boulic and D. Thalmann, 'Real-time display of virtual humans: Level of details and impostors,' IEEE Transactions on Circuits and Systems for Video Technology, Special Issue on 3D Video Technology, 10(2): 207-217, 2000 https://doi.org/10.1109/76.825720
  16. F. Tecchia, C. Loscos and Y. Chrysanthou, 'Image Based Crowd Rendering,' IEEE CG&A March/April, pp.36-43, 2002 https://doi.org/10.1109/38.988745
  17. S. Dobbyn, J. Hamill, K. O'Conor and C. O'Sullivan 'Geopostors: A real-time geometry / impostor crowd rendering system,' I3D 2005 https://doi.org/10.1145/1053427.1053443
  18. Z. Popovic and A. Witkin, 'Physically based motion transformation,' ACM SIGGRAPH 99, pp.11-20, 1999 https://doi.org/10.1145/311535.311536
  19. J. Ahn, C. Sui, E. Park and K. Wohn, 'Development of LAN-based Optical Motion Capture System,' HCI 2000
  20. J. Ahn, M. Jang and K. Wohn, 'Trajectory Rectification of Marker using Confidence Model,' KCGS Journal, 8(3):17-23, 2002
  21. K. Shoemake and T. Duff, 'Matrix Animation and Polar Decomposition,' Proceedings of Graphics Interface, pp.245-254, 1992
  22. S. Oh, H. Kim, N. Magnenat-Thalmann and K. Wohn, 'Generating unified model for dressed virhumans,' The Visual Computer 21(8): 522 2005 https://doi.org/10.1007/s00371-005-0339-6