GPU accelerated particle methods for simulating and rendering fire and water effects

186 Pages·2016·2.98 MB·English

by  Lyes, Timothy

Copyright is owned by the Author of the thesis. Permission is given for
a copy to be downloaded by an individual for the purpose of research and
private study only. The thesis may not be reproduced elsewhere without
the permission of the Author.
GPU Accelerated Particle Methods for Simulating and
Rendering Fire and Water Effects
A thesis presented in partial fulfillment of the requirements
for the degree of
Doctor of Philosophy
in
Computer Science
at Massey University, Albany
New Zealand.
Timothy Lyes
2015

Abstract
Thesimulationofcomplexnaturalphenomenasuchasfireandwaterisacomplicatedproblem
and with the surge in popularity of video games and other interactive media, it has become
an area of interest in computer graphics to be able to simulate these phenomena in real-time.
Thechallengeexistsnotonlytosimulateasaccuratelyaspossibleforthebestdegreeofvisual
realism,butalsotouseamethodwhichallowsforthisreal-timeinteraction.
In this thesis, the use of particle systems as a method for simulating fire and water effects
is explored, as well as the rendering methods used to visualize them. Particle systems are
well suited to this type of problem as they can be parallelized and provide many methods
of behavioural customization in order to produce a wide range of different effects. Realistic
lookingresultscanbeachievedwhenasufficientnumberofparticlesareabletobesimulated
withinanadequatetimeframe.
It can be shown that particle system methods such as Smoothed Particle Hydrodynamics
and Velocity-Vortex methods are able to simulate these phenomena well. These methods are
implemented using NVIDIA CUDA to parallelize the governing algorithms on the graphics
processor, and with the use of spatial grid division techniques to reduce the computational
complexity,theyareabletorunatreal-timeinteractiverates.
Additionally, when utilizing point-based approaches for rendering fire, and a surface gen-
eration approach using the Marching Cubes algorithm for rendering water, it can be shown
that these particle systems are able to be rendered with realistic-looking visualizations while
maintaininginteractivity. Combiningboththecomputationalaspectsoftheparticlesystemand
the rendering aspects directly on the graphics device produces good quality rendered fire and
watereffectsatspeedsfastenoughtobeusedwithinteractivemediaapplications.

Acknowledgements
I would like to thank everyone who has supported me. In particular I would like to thank my
parents,JoannaandRex,andmytwosisters,AmyandSusannah,whohavecontinuedtolove
and support me during this endeavour. I would also like to thank my supervisors, Dr. Arno
Leist,Dr. DanielPlayneandProf. KenHawickfortheirguidanceandexpertise,aswellasall
mycolleaguesatMasseyUniversityfortheircamaraderieandencouragement.

CONTENTS
ListofFigures 6
ListofTables 9
1 Introduction 11
1.1 AimandResearchMethodsoftheThesis . . . . . . . . . . . . . . . . . . . . 13
1.2 KeyContributionsoftheThesis . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.3 StructureoftheThesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2 IntroductiontoParticleSystems 17
2.1 ParticleSystemsOverview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2 FluidFlowandHydrodynamics . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.3 OtherRelatedParticleModels . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3.1 Agent-BasedModels . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3.2 Spring-MassModels . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3.3 OtherNotableWork . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.4 RenderingEffects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.5 NumericalMethodsandIntegration . . . . . . . . . . . . . . . . . . . . . . . 27
2.5.1 EulerIntegrationMethod . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5.2 Euler-CromerMethod . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.5.3 Runge-Kutta(2ndOrder) . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.5.4 Runge-Kutta(4thOrder) . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.5.5 LeapfrogMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.6 ComputationalComplexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.7 IntroductiontoParallelization . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3 IntroductiontoParallelization 35
3.1 CUDAProgrammingModel . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.2 KeplerArchitecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4 CONTENTS
3.3 CUDAMemory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.4 ParallelizationofParticleMethods . . . . . . . . . . . . . . . . . . . . . . . . 42
3.5 CUDALibraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.5.1 Thrust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.5.2 CURANDRandomNumberGeneration . . . . . . . . . . . . . . . . . 45
3.6 GraphicsCards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4 ParticleSystemModels 47
4.1 Non-interactingParticleModel . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.2 Spring-MassModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.3 SmoothedParticleHydrodynamics . . . . . . . . . . . . . . . . . . . . . . . . 52
4.3.1 Navier-StokesFluidFlow . . . . . . . . . . . . . . . . . . . . . . . . 53
4.3.2 SPHEquations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4.4 Velocity-VortexModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.4.1 Rigid-BodyInteraction . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5 SpatialGridandIntegrationMethods 63
5.1 SpatialGridAlgorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.1.1 SpatialGrid-basedCollisionDetection . . . . . . . . . . . . . . . . . 64
5.1.2 SortingConsiderations . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.1.3 SpatialGridImplementation . . . . . . . . . . . . . . . . . . . . . . . 68
5.2 NumericalIntegration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.2.1 IntegrationImplementation . . . . . . . . . . . . . . . . . . . . . . . . 70
5.2.2 IntegrationMethodComparison . . . . . . . . . . . . . . . . . . . . . 74
5.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6 Implementation 85
6.1 FireIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.2 Non-interactingFireImplementation . . . . . . . . . . . . . . . . . . . . . . . 86
6.3 PlasmaImplementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.3.1 PlasmaSystemOverview. . . . . . . . . . . . . . . . . . . . . . . . . 91
6.3.2 Plasma-specificSpatialGridAnalysis . . . . . . . . . . . . . . . . . . 93
6.3.3 InteractionProcessing . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.4 Velocity-VortexFireImplementation . . . . . . . . . . . . . . . . . . . . . . . 98
6.4.1 FireSystemInitialization . . . . . . . . . . . . . . . . . . . . . . . . . 101
6.4.2 DynamicSpatialGrid . . . . . . . . . . . . . . . . . . . . . . . . . . 101
6.4.3 VorticityDynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6.4.4 BuoyancyHandling . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.4.5 AdvectionStepandBodyCollision . . . . . . . . . . . . . . . . . . . 107
6.4.6 FirePerformanceComparison . . . . . . . . . . . . . . . . . . . . . . 108
CONTENTS 5
6.5 WaterImplementation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
6.5.1 Spring-MassSystemImplementation . . . . . . . . . . . . . . . . . . 110
6.5.2 SmoothedParticleHydrodynamicsImplementation . . . . . . . . . . . 113
6.5.3 SPHvsSpring-MassComparison . . . . . . . . . . . . . . . . . . . . 117
6.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
7 Rendering 121
7.1 RenderingIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
7.2 Point-BasedRenderingMethod . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7.3 FireVisualComparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
7.4 VolumetricRendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.5 SurfaceGeneration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
7.5.1 IsosurfaceIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . 132
7.5.2 MarchingCubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
7.5.3 Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
7.5.4 ImplementationOverview . . . . . . . . . . . . . . . . . . . . . . . . 138
7.5.5 CellClassificationApproaches . . . . . . . . . . . . . . . . . . . . . . 138
7.5.6 GeneratingtheSurface . . . . . . . . . . . . . . . . . . . . . . . . . . 142
7.6 SurfaceRendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
7.6.1 SurfaceRendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
7.6.2 CubemappingandFresnelReflection . . . . . . . . . . . . . . . . . . 146
7.7 ResultsDiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
7.8 RealismComparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
7.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
8 DiscussionsandConclusions 161
8.1 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
8.1.1 NumericalIntegrationandSpatialPartitioning . . . . . . . . . . . . . 162
8.1.2 ChoicesinFireandWaterSimulationModels . . . . . . . . . . . . . . 163
8.1.3 SurfaceGenerationandRendering . . . . . . . . . . . . . . . . . . . . 165
8.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
8.3 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168