한국컴퓨터그래픽스학회논문지 (Journal of the Korea Computer Graphics Society)

  • 제23권1호
  • /
  • Pages.9-16
  • /
  • 2017
  • /
  • 1975-7883(pISSN)
  • /
  • 2383-529X(eISSN)
한국컴퓨터그래픽스학회 (Korea Computer Graphics Society)
권호 표지
DOI QR코드

DOI QR Code

젖은 헤어와 털 시뮬레이션을 위한 효율적인 응집력과 강성 처리

Efficient Treatment of Clumping and Stiffness for Wet Hair and Fur Simulation

  • 투고 : 2016.11.23
  • 심사 : 2017.03.07
  • 발행 : 2017.03.07
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

젖은 헤어 또는 동물의 털 시뮬레이션에서 응집력과 강성(stiffness)을 처리하는 것은 어려운 문제이다. 격렬한 움직임을 갖는 헤어나 털이 물에 젖게 되면 끝이 뭉치고 빳빳해지는 현상이 나타나게 되는데, 이는 달리는 동물이나 헤드뱅잉 하는 장면 등에서 쉽게 관찰 할 수 있다. 기존의 방법들은 정해진 시뮬레이션 시나리오에서 이 문제를 해결하려고 했지만 여전히 젖은 헤어의 특징을 묘사하기 위한 일반적인 방법이 존재하지 않는다. 이 문제를 해결하기 위해 우리는 응집력과 강성에 대한 새로운 모델링 방법을 제안한다. 기존 연구들은 물이 모발에 흡수되는 현상을 모델링 하는데 초점을 맞춘 반면, 우리는 젖은 모발의 움직임을 사실적으로 표현하는데 집중한다. 젖은 헤어는 마른 헤어와는 다르게 인접한 모발들끼리 응집력이 작용하여 서로 뭉치는 형태를 띄며, 물의 포화도가 높아질수록 빳빳해지는 독특한 물리적 특성이 나타난다. 제안된 기법의 핵심은 SPH (smoothed particle hydrodynamics) 기반의 표면 장력 모델을 확장하여 응집력을 표현하고, 강성 제약을 두어 모발의 탄성력을 조절하는 것이다. 우리 기법은 젖은 모발이 격렬한 움직임에서도 응집력을 잘 유지할 수 있도록 도와주며, 물의 포화도에 따른 모발의 빳빳함을 표현하여 사실적인 젖은 헤어 시뮬레이션 결과를 보여준다.

Simulating the clumping and stiffness of wet hair or fur is a challenging problem. The dynamics of wet hair or fur is characterized by the clumping and stiffness at the tip, which is easily seen in running animals or headbanging scenes. Existing methods address these phenomenon within pre-set scenarios. But there is no consensus on the method of depicting the details of wet hair. Hence, the present paper proposes a new method of modeling the clumping and stiffness of wet hair or fur. Previous studies focused on modeling the absorption of water into hair or fur, whereas this paper highlights a realistic simulation of wet hair. Unlike dry hair strands, wet hair strands adjacent to one another are subjected to the clumping force and gather together, while at the same time becoming stiff as the saturation of water increases. The proposed method builds on the surface tension model based on SPH (smoothed particle hydrodynamics) to simulate the clumping force and to adjust the hair elasticity by giving stiffness constraints. The present method enables a realistic simulation of wet hair by maintaining the clumping force of the wet hair even in dynamic motions, and by simulating the stiffness of hair in line with water saturation.

키워드

과제정보

연구 과제 주관 기관 : Hallym University, Institute for Information & communications Technology Promotion(IITP), National Research Foundation of Korea (NRF)

참고문헌

  1. W. Rungjiratananon, Z. Szego, Y. Kanamori, and T. Nishita, "Real-time animation of sand-water interaction," in Computer Graphics Forum, vol. 27, no. 7, 2008, pp. 1887-1893. https://doi.org/10.1111/j.1467-8659.2008.01336.x
  2. W.-C. Lin, "Boundary handling and porous flow for fluid-hair interactions," Computers & Graphics, vol. 52, pp. 33-42, 2015. https://doi.org/10.1016/j.cag.2015.06.005
  3. C. Yuksel, S. Schaefer, and J. Keyser, "Hair meshes," in ACM SIGGRAPH Asia, 2009, pp. 166:1-166:7.
  4. B. Choe, M. G. Choi, and H.-S. Ko, "Simulating complex hair with robust collision handling," in Proceedings of the 2005 ACM SIGGRAPH/Eurographics symposium on Computer animation, 2005, pp. 153-160.
  5. A. Selle, M. Lentine, and R. Fedkiw, "A mass spring model for hair simulation," in ACM SIGGRAPH, vol. 27, no. 3, 2008, p. 64.
  6. M. Muller, T.-Y. Kim, and N. Chentanez, "Fast simulation of inextensible hair and fur." VRIPHYS, vol. 12, pp. 39-44, 2012.
  7. M.Muller, B. Heidelberger, M. Hennix, and J. Ratcliff, "Position based dynamics," Journal of Visual Communication and Image Representation, vol. 18, no. 2, pp. 109-118, 2007. https://doi.org/10.1016/j.jvcir.2007.01.005
  8. J. Brown, J.-C. Latombe, and K. Montgomery, "Real-time knot-tying simulation," The Visual Computer, vol. 20, no. 2-3, pp. 165-179, 2004. https://doi.org/10.1007/s00371-003-0226-y
  9. T. Lenaerts, B. Adams, and P. Dutre, "Porous flow in particlebased fluid simulations," in ACM Transactions on Graphics (TOG), vol. 27, no. 3, 2008, p. 49. https://doi.org/10.1145/1360612.1360648
  10. T. Lenaerts and P. Dutre, "Mixing fluids and granular materials," in Computer Graphics Forum, vol. 28, no. 2, 2009, pp. 213-218. https://doi.org/10.1111/j.1467-8659.2009.01360.x
  11. S. Baek, K. Um, and J. Han, "Muddy water animation with different details," Computer Animation and Virtual Worlds, vol. 26, no. 3-4, pp. 347-355, 2015. https://doi.org/10.1002/cav.1646
  12. Y. Chen, N. M. Thalmann, and B. F. Allen, "Physical simulation of wet clothing for virtual humans," The Visual Computer, vol. 28, no. 6-8, pp. 765-774, 2012. https://doi.org/10.1007/s00371-012-0687-y
  13. K. Um, T.-Y. Kim, Y. Kwon, and J. Han, "Porous deformable shell simulation with surface water flow and saturation," Computer Animation and Virtual Worlds, vol. 24, no. 3-4, pp. 247-254, 2013. https://doi.org/10.1002/cav.1497
  14. W. Rungjiratananon, Y. Kanamori, and T. Nishita, "Wetting effects in hair simulation," in Computer Graphics Forum, vol. 31, no. 7, 2012, pp. 1993-2002. https://doi.org/10.1111/j.1467-8659.2012.03191.x
  15. N. Akinci, M. Ihmsen, G. Akinci, B. Solenthaler, and M. Teschner, "Versatile rigid-fluid coupling for incompressible sph," ACM Transactions on Graphics (TOG), vol. 31, no. 4, p. 62, 2012.
  16. M. Muller, D. Charypar, and M. Gross, "Particle-based fluid simulation for interactive applications," in ACM SIGGRAPH/ Eurographics Symposium on Computer Animation, 2003, pp. 154-159.
  17. N. Akinci, J. Cornelis, G. Akinci, and M. Teschner, "Coupling elastic solids with smoothed particle hydrodynamics fluids," Computer Animation and Virtual Worlds, vol. 24, no. 3-4, pp. 195-203, 2013. https://doi.org/10.1002/cav.1499
  18. N. Akinci, G. Akinci, and M. Teschner, "Versatile surface tension and adhesion for sph fluids," ACM Transactions on Graphics (TOG), vol. 32, no. 6, p. 182, 2013.
  19. E. Guendelman, A. Selle, F. Losasso, and R. Fedkiw, "Coupling water and smoke to thin deformable and rigid shells," ACM Transactions on Graphics (TOG), vol. 24, no. 3, pp. 973-981, 2005. https://doi.org/10.1145/1073204.1073299
  20. A. Robinson-Mosher, T. Shinar, J. Gretarsson, J. Su, and R. Fedkiw, "Two-way coupling of fluids to rigid and deformable solids and shells," in ACM Transactions on Graphics (TOG), vol. 27, no. 3, 2008, p. 46. https://doi.org/10.1145/1360612.1360645
  21. P. Du, M. Tang, C. Meng, R. Tong, and L. Lin, "A fluid/cloth coupling method for high velocity collision simulation," in Proceedings of the 11th ACM SIGGRAPH International Conference on Virtual-Reality Continuum and its Applications in Industry, 2012, pp. 309-314.
  22. M. Muller, S. Schirm, M. Teschner, B. Heidelberger, and M. Gross, "Interaction of fluids with deformable solids," Computer Animation and Virtual Worlds, vol. 15, no. 3-4, pp. 159-171, 2004. https://doi.org/10.1002/cav.18
  23. B. Solenthaler, J. Schlafli, and R. Pajarola, "A unified particle model for fluid-solid interactions," Computer Animation and Virtual Worlds, vol. 18, no. 1, pp. 69-82, 2007. https://doi.org/10.1002/cav.162
  24. L. Yang, S. Li, A. Hao, and H. Qin, "Realtime two-way coupling of meshless fluids and nonlinear fem," in Computer Graphics Forum, vol. 31, no. 7, 2012, pp. 2037-2046. https://doi.org/10.1111/j.1467-8659.2012.03196.x
  25. Y. Zhu and R. Bridson, "Animating sand as a fluid," in ACM Transactions on Graphics (TOG), vol. 24, no. 3, 2005, pp. 965-972. https://doi.org/10.1145/1073204.1073298
  26. D. Enright, S. Marschner, and R. Fedkiw, "Animation and rendering of complex water surfaces," ACM Transactions on Graphics (TOG), vol. 21, no. 3, pp. 736-744, 2002. https://doi.org/10.1145/566654.566645