1. Modelling Realistic Water & Fire Sérgio Leal Socrates/Erasmus student at: AK Computer Graphics Institute for Computer Graphics and Vision Technical University of Graz 2002/2003mcamara@sbox.TUGraz.at

2. Introduction Why model realistic Water and Fire? Why model realistic Water and Fire? Applications Applications How to model How to model Similarities and differences Similarities and differences Conclusion Conclusion

3. Why model Water & Fire? Better Visualisation and understanding of Physical/Natural Phenomena Better Visualisation and understanding of Physical/Natural Phenomena Film Industry Film Industry VR VR Pure Pleasure Pure Pleasure By Sérgio Leal

4. Applications - Engineering Model realistic physical movements and object interactions Model realistic physical movements and object interactions Better understanding of physical phenomena Better understanding of physical phenomena Better calculation of human constructions and nature interactions Better calculation of human constructions and nature interactions

5. Applications - Animation Visualisation on the process of learning Visualisation on the process of learning VR VR Film Film Art Art Image from [Enright et al. 2002] By Sérgio Leal

6. How to model? The Navier-Stokes Equations The Navier-Stokes Equations Conservation of the mass Conservation of the mass ∆.u = 0, where u is the liquid velocity field and on 3D, ∆ = (δ/δx, δ/δy, δ/δz) ∆.u = 0, where u is the liquid velocity field and on 3D, ∆ = (δ/δx, δ/δy, δ/δz) Conservation of the momentum Conservation of the momentum ut = ν ∆∙ (∆u) - (u∙∆)u-(1/ ρ )∆p +g, where ν is viscosity, ρ is density, p is pressure and g is gravity

7. How to model Water? [Foster and Fedkiw 2001] [Foster and Fedkiw 2001] Define a container Define a container Cells can be empty or solid Cells can be empty or solid Liquid can only occupy the empty/unfilled cells Liquid can only occupy the empty/unfilled cells Represent liquid using implicit surfaces Represent liquid using implicit surfaces Smooth surface with dynamic isocontour Smooth surface with dynamic isocontour Volume modeling Volume modeling Image from [Foster and Fedkiw 2001]

8. How to model Water? [Enright et al. 2002] [Enright et al. 2002] Improved [Foster and Fedkiw 2001] model Improved [Foster and Fedkiw 2001] model New front tracking technique for Water surface representation New front tracking technique for Water surface representation Velocity extrapolation Velocity extrapolation Better Water surface effect Better Water surface effect Surface modeling Surface modeling Refraction on the light impression improved Refraction on the light impression improved Image from [Enright et al. 2002]

9. How to model Fire? [Nguyen et al. 2002] [Nguyen et al. 2002] Represent the expansion of the vaporized fuel Represent the expansion of the vaporized fuel Smoke, black radiance and the blue core Smoke, black radiance and the blue core Chemical reaction Chemical reaction Implicit surface Implicit surface Incompressible flow Incompressible flow Stable fluids Stable fluids Image from [Nguyen et al. 2002]

10. Similarities Both are implicit surfaces Both are implicit surfaces Physical based models Physical based models Can be described as a fluid like movement Can be described as a fluid like movement Semi-Lagrangian Stable Fluids approach Semi-Lagrangian Stable Fluids approach Image from [Nguyen et al. 2002] Image from [Foster and Fedkiw 2001]

11. Differences Water Water Computational fluid dynamics Computational fluid dynamics Reflection Reflection Tend to be stable Tend to be stable Fire Fire Incompressible flow Incompressible flow Very instable Very instable Chemical reaction Chemical reaction Smoke Smoke Radiance Radiance [Nguyen et al. 2002] Image from [Enright et al. 2002]

12. Conclusion Very fascinating Very fascinating A lot to be done A lot to be done Many applications Many applications By Sérgio Leal

13. References Papers Papers Enright, D. Marschner, S. and Fedkiw, R. 2002. Animation and Rendering of Complex Water Surfaces. in Proceedings of SIGGRAPH 2002. Enright, D. Marschner, S. and Fedkiw, R. 2002. Animation and Rendering of Complex Water Surfaces. in Proceedings of SIGGRAPH 2002. FOSTER, N. and FEDKIW, R. 2001. Practical animation of liquids. in Proceedings of SIGGRAPH 2001, ACM Press / ACM SIGGRAPH, E. Fiume, Ed., Computer Graphics Proceedings. Annual Conference Series, ACM, 23–30. FOSTER, N. and FEDKIW, R. 2001. Practical animation of liquids. in Proceedings of SIGGRAPH 2001, ACM Press / ACM SIGGRAPH, E. Fiume, Ed., Computer Graphics Proceedings. Annual Conference Series, ACM, 23–30. Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002. Physically Based Modeling and Animation of Fire. in Proceedings of SIGGRAPH 2002. Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002. Physically Based Modeling and Animation of Fire. in Proceedings of SIGGRAPH 2002. Images Images Water Water Enright, D. Marschner, S. and Fedkiw, R. 2002. Enright, D. Marschner, S. and Fedkiw, R. 2002. Leal, S. 2003 Leal, S. 2003 Fire Fire Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002. Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002. Leal, S. 2003 Leal, S. 2003

14. Thank you for your attention Modelling Realistic Water & Fire Sérgio Leal Socrates/Erasmus student at: AK Computer Graphics Institute for Computer Graphics and Vision Technical University of Graz 2002/2003mcamara@sbox.TUGraz.at