Modelling Realistic Water

1
Modelling Realistic Water Fire

• Sérgio Leal
• Socrates/Erasmus student at
• AK Computer Graphics
• Institute for Computer Graphics and Vision
• Technical University of Graz
• 2002/2003
• mcamara_at_sbox.TUGraz.at

2
Introduction

• Why model realistic Water and Fire?
• Applications
• How to model
• Similarities and differences
• Conclusion

3
Why model Water Fire?

• Better Visualisation and understanding of
  Physical/Natural Phenomena
• Film Industry
• VR
• Pure Pleasure

By Sérgio Leal
4
Applications - Engineering

• Model realistic physical movements and object
  interactions
• Better understanding of physical phenomena
• Better calculation of human constructions and
  nature interactions

5
Applications - Animation

• Visualisation on the process of learning
• VR
• Film
• Art

Image from Enright et al. 2002
By Sérgio Leal
6
How to model?

• The Navier-Stokes Equations
• Conservation of the mass
• ? .u 0, where u is the liquid velocity field
  and on 3D, ? (d/dx, d/dy, d/dz)
• Conservation of the momentum
• ut ? ? (?u) - (u?)u-(1/ ? )?p g, where ? is
  viscosity, ? is density, p is pressure and g is
  gravity

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How to model Water?

• Foster and Fedkiw 2001
• Define a container
• Cells can be empty or solid
• Liquid can only occupy the empty/unfilled cells
• Represent liquid using implicit surfaces
• Smooth surface with dynamic isocontour
• Volume modeling

Image from Foster and Fedkiw 2001
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How to model Water?

• Enright et al. 2002
• Improved Foster and Fedkiw 2001 model
• New front tracking technique for Water surface
  representation
• Velocity extrapolation
• Better Water surface effect
• Surface modeling
• Refraction on the light impression improved

Image from Enright et al. 2002
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How to model Fire?

• Nguyen et al. 2002
• Represent the expansion of the vaporized fuel
• Smoke, black radiance and the blue core
• Chemical reaction
• Implicit surface
• Incompressible flow
• Stable fluids

Image from Nguyen et al. 2002
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Similarities

• Both are implicit surfaces
• Physical based models
• Can be described as a fluid like movement
• Semi-Lagrangian Stable Fluids approach

Image from Nguyen et al. 2002
Image from Foster and Fedkiw 2001
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Differences

• Water
• Computational fluid dynamics
• Reflection
• Tend to be stable
• Fire
• Incompressible flow
• Very instable
• Chemical reaction
• Smoke
• Radiance

Nguyen et al. 2002
Image from Enright et al. 2002
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Conclusion

• Very fascinating
• A lot to be done
• Many applications

By Sérgio Leal
13
References

• Papers
• 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, 2330.
• Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002.
  Physically Based Modeling and Animation of Fire.
  in Proceedings of SIGGRAPH 2002.
• Images
• Water
• Enright, D. Marschner, S. and Fedkiw, R. 2002.
• Leal, S. 2003
• Fire
• Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002.
• 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
• 2002/2003
• mcamara_at_sbox.TUGraz.at