Modelling Realistic Modelling Realistic Water & FireWater & Fire

Sérgio LealSérgio Leal Socrates/Erasmus student at:Socrates/Erasmus student at:

AK Computer GraphicsAK Computer GraphicsInstitute for Computer Graphics and VisionInstitute for Computer Graphics and Vision

Technical University of Graz Technical University of Graz 2002/20032002/2003

mcamara@sbox.TUGraz.atmcamara@sbox.TUGraz.at

IntroductionIntroduction

Why model realistic Water and Fire?Why model realistic Water and Fire? ApplicationsApplications How to modelHow to model Similarities and differencesSimilarities and differences ConclusionConclusion

Why model Water & Why model Water & Fire?Fire?

Better Visualisation and understanding Better Visualisation and understanding of Physical/Natural Phenomenaof Physical/Natural Phenomena

Film IndustryFilm Industry VRVR Pure PleasurePure Pleasure

By Sérgio LealBy Sérgio Leal

Applications - EngineeringApplications - Engineering

Model realistic physical movements Model realistic physical movements and object interactionsand object interactions

Better understanding of physical Better understanding of physical phenomenaphenomena

Better calculation of human Better calculation of human constructions and nature interactionsconstructions and nature interactions

Applications - AnimationApplications - Animation

Visualisation on the process of learning Visualisation on the process of learning VRVR FilmFilm ArtArt

Image from [Enright et al. 2002]Image from [Enright et al. 2002] By Sérgio LealBy Sérgio Leal

How to model?How to model?

The Navier-Stokes EquationsThe Navier-Stokes Equations Conservation of the massConservation of the mass

∆ ∆ .u = 0, where u is the liquid velocity field .u = 0, where u is the liquid velocity field and on 3D, ∆ = and on 3D, ∆ = (δ/δx, δ/δy, δ/δz)(δ/δx, δ/δy, δ/δz)

Conservation of the momentumConservation 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

How to model Water?How to model Water?

[Foster and Fedkiw [Foster and Fedkiw 2001]2001] Define a containerDefine a container Cells can be empty or Cells can be empty or

solidsolid Liquid can only occupy Liquid can only occupy

the empty/unfilled cellsthe empty/unfilled cells Represent liquid using Represent liquid using

implicit surfacesimplicit surfaces Smooth surface with Smooth surface with

dynamic isocontourdynamic isocontour Volume modeling Volume modeling

Image from [Foster and Fedkiw 2001]Image from [Foster and Fedkiw 2001]

How to model Water?How to model Water?

[Enright et al. 2002][Enright et al. 2002] Improved Improved [Foster and [Foster and

Fedkiw 2001] modelFedkiw 2001] model New front tracking New front tracking

technique for Water technique for Water surface representation surface representation

Velocity extrapolationVelocity extrapolation Better Water surface Better Water surface

effecteffect Surface modeling Surface modeling Refraction on the light Refraction on the light

impression improved impression improved

Image from [Enright et al. 2002]Image from [Enright et al. 2002]

How to model Fire?How to model Fire?

[Nguyen et al. [Nguyen et al. 2002]2002] Represent the Represent the

expansion of the expansion of the vaporized fuel vaporized fuel

Smoke, black radiance Smoke, black radiance and the blue core and the blue core

Chemical reactionChemical reaction Implicit surfaceImplicit surface Incompressible flowIncompressible flow Stable fluidsStable fluids

Image from [Nguyen et al. 2002] Image from [Nguyen et al. 2002]

SimilaritiesSimilarities

Both are implicit Both are implicit surfacessurfaces

Physical based Physical based modelsmodels

Can be described as Can be described as a fluid like a fluid like movementmovement

Semi-Lagrangian Semi-Lagrangian Stable Fluids Stable Fluids approachapproach

Image from [Nguyen et al. 2002]Image from [Nguyen et al. 2002]

Image from [Foster and Fedkiw 2001]Image from [Foster and Fedkiw 2001]

DifferencesDifferences

WaterWater Computational fluid dynamicsComputational fluid dynamics ReflectionReflection Tend to be stableTend to be stable

Fire Fire Incompressible flowIncompressible flow Very instableVery instable Chemical reactionChemical reaction SmokeSmoke RadianceRadiance

[Nguyen et al. 2002][Nguyen et al. 2002]Image from [Enright et al. 2002]Image from [Enright et al. 2002]

ConclusionConclusion

Very fascinatingVery fascinating A lot to be doneA lot to be done Many applicationsMany applications

By Sérgio LealBy Sérgio Leal

ReferencesReferences PapersPapers

Enright, D. Marschner, S. and Fedkiw, R. 2002. Animation and Enright, D. Marschner, S. and Fedkiw, R. 2002. Animation and Rendering of Complex Water Surfaces. Rendering of Complex Water Surfaces. iin n Proceedings of SIGGRAPH Proceedings of SIGGRAPH 2002.2002.

FOSTER, N. and FEDKIW, R. 2001. Practical animation of liquids.FOSTER, N. and FEDKIW, R. 2001. Practical animation of liquids. i in n Proceedings of SIGGRAPH 2001Proceedings of SIGGRAPH 2001, ACM Press / ACM SIGGRAPH, E. , ACM Press / ACM SIGGRAPH, E. Fiume, Ed., Computer Graphics Proceedings. Annual Conference Fiume, Ed., Computer Graphics Proceedings. Annual Conference Series, ACM, 23–30.Series, ACM, 23–30.

Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002. Physically Based Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002. Physically Based Modeling and Animation of Fire. Modeling and Animation of Fire. iin n Proceedings of SIGGRAPH 2002Proceedings of SIGGRAPH 2002..

Images Images WaterWater

Enright, D. Marschner, S. and Fedkiw, R. 2002.Enright, D. Marschner, S. and Fedkiw, R. 2002. Leal, S. 2003Leal, S. 2003

FireFire Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002.Nguyen, D. Q. Fedkiw, R and Jensen, H. W. 2002. Leal, S. 2003Leal, S. 2003

Thank you for your Thank you for your attentionattention

Modelling Realistic Water & FireModelling Realistic Water & Fire

Sérgio LealSérgio Leal Socrates/Erasmus student at:Socrates/Erasmus student at:

AK Computer GraphicsAK Computer GraphicsInstitute for Computer Graphics and VisionInstitute for Computer Graphics and Vision

Technical University of Graz Technical University of Graz 2002/20032002/2003

mcamara@sbox.TUGraz.atmcamara@sbox.TUGraz.at