Crowd Simulation

304 Pages·2013·14.049 MB·English

by  Daniel Thalmann, Soraia Raupp Musse (auth.)

Crowd Simulation
Daniel Thalmann (cid:2) Soraia Raupp Musse
Crowd Simulation
Second Edition
DanielThalmann SoraiaRauppMusse
InstituteforMediaInnovation GraduateCourseinComputerScience
NanyangTechnologicalUniversity PontificalCatholicUniversityofRio
Singapore,Singapore GrandedoSul
and PortoAlegre,RioGrandedoSul,Brazil
IC-DO
EPFL
Lausanne,Switzerland
ISBN978-1-4471-4449-6 ISBN978-1-4471-4450-2(eBook)
DOI10.1007/978-1-4471-4450-2
SpringerLondonHeidelbergNewYorkDordrecht
LibraryofCongressControlNumber:2012950038
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(Daniel)
To mybelovedwifeNadiaand beloved
daughters Melanie,Vanessa, andSabrina
(Soraia)
To my daughters Marina and Helena and
husband Claudio,whoenlightenmylife.
Preface
Thisbooksurveysalgorithmsandtechniquesofcrowdsimulation,andisintended
forgraduatestudents,researchers,andprofessionals.Inparticular,computeranima-
tionresearchers,developers,designers,andurbanplannerswillgreatlybenefitfrom
thisbook.Thissecondeditionpresentsnewtechniquesandmethodsproposedsince
2007,whenwepublishedthefirsteditionofthebook.
In 1996, when the authors started researching into crowd simulation, there was
verylittlematerialavailableonthistopicintheComputerScienceliterature.Daniel
ThalmannsupervisedSoraiaRauppMusse’sPhDthesisin1997andsincethenthey
have both extensively published in the domain. As a result, many other research
groups have also started working in the area. As early pioneers in this research,
theauthorsorganizedthefirstworkshoponCrowdSimulation(V-Crowds)in2005
inLausanne.Today,DanielThalmannattheNanyangTechnologicalUniversityin
SingaporeandSoraiaRauppMusseatPUCRSinBrazilkeepworkingoncrowds.
Crowdsimulationisnowapopularareaofresearchandmanytechniqueshavebeen
developed, with the entertainment industry in particular realising the potential of
crowdanimation.Butwhyisthissubjectsofascinating?
Aggregatedmotionisbothbeautifulandcomplextocontemplate.Beautifuldue
tothesynchronisation,homogeneityandunitydescribedinthistypeofmotion,and
complexbecausetherearemanyparameterstobehandledinordertoprovidethese
characteristics.Historyshowsthattherehasalwaysbeeninterestinunderstanding
and controlling the motion and behaviour of crowds of people. Psychologists and
sociologistshavestudiedthebehavioursofgroupsofpeopleforseveralyears,pri-
marilytostudytheeffectsthatoccurwhenpeoplewiththesamegoalbecomeone
entity—acrowdor a mass. Whenthis happens,peoplecanlose theirindividuality
andadoptthebehaviourofthecrowdentity,behavinginadifferentwaythanifthey
werealone.
The simulation of large crowds in real time requires many instances of simi-
lar characters. We need algorithms to allow for each individualin the crowd to be
unique.Inthisbookwepresentsomepossibilitiesofcharactergenerationandcus-
tomization. We emphasize population modelling, including shapes, sizes, and col-
ors.Wealsodiscusstheimportanceofaddingaccessorieslikebags,glasses,mobile
vii
viii Preface
phones,andtheirimpactonanimation.Thistopicisveryimportantinthesensethat
itprovidescoherentvisualizationofpopulations,asdiscussedinChap.3.
Crowdanimationisfundamentallybasedontheanimationoftheindividualvir-
tualhumans.Chapter4explainsthemethodsusedtoanimatetheseindividualsespe-
ciallytheirlocomotion.WeexplainwalkingmodelsbasedonmethodslikePrincipal
ComponentAnalysis.Wealsoinsistonanimationvarietyasitisessentialforreal-
isticcrowdbehaviour.
Certain problems arise only when studying crowds. For instance, crowds have
acertainintelligenceincollectivebehaviors,whilstindividualintelligenceandbe-
haviorscanbeobservedatthesametime.Interaction(verbalornon-verbal)among
individuals, groups and crowds can be perceived in low density flow of persons.
Navigationisprobablythemostcrucialbehaviorforcrowdsthatcanbesimulated
on a computer. We discuss in detail techniques of path planning including a new
hybridapproachbetweennavigationgraphsandpotential-basedmethods.Collision
avoidance problems related to a large number of individuals in the same place re-
quiredifferentstrategiesincomparisonwiththemethodsusedtoavoidcollisionbe-
tweenindividuals.Inreallifepeoplecanstopbecausetheydon’thaveenoughspace
towalk,andunfortunatelytheycanevendiebecausethehighdensityofindividuals
inthesamespace.WealsointroducedanewSectionongazeattentionaswethinkit
isimportantthatindividualsseemawareoftheenvironmentandotherpeople.The
relationshipbetweenpeopleandtheenvironmentisgivenbysomeaspectssuchas
culture,knowledge,experience,memory,etc.Computersshouldgeneratebehavior
patternstoachievesuchlevelsofinteraction.Chapters4and5presentsomeaspects
tocontributewiththisdiscussion.
Moreover,acrowdisnotonlyalargegroupofindividuals,butcanalsobeformed
by groups which in turn are related to individuals. In addition other levels of be-
haviour can exist when treating crowds in this hierarchical structure. The group
behaviourscanbeusedtospecifythewayagroupmoves,behavesandacts.Individ-
ualabilitiescanalsoberequiredinordertoimprovetheautonomyandintelligence
ofcrowds,forinstanceperception,emotionalstatus,memory,communication,etc.
However, when we consider thousands of individuals, these complex behaviours
cannot be provided individually due to the hardware constraints and to computa-
tionaltimerates.Afurtherproblemrelatestohowtoimprovetheintelligenceand
provideautonomytoscalablecrowds,inreal-timesystems.InChap.6wediscuss
theintegrationofcrowdsimulationandcomputervisiontobringnewgroundinthis
discussion.
Chapter 7 discusses techniques for rendering crowds especially when real time
simulationsarerequiredtopopulatevirtualenvironmentsinvirtualrealitysystems.
Weintroduceacompletepipelineforfastrenderingincludinglevelsofdetails,de-
formable and non-deformable characters as well as impostors. A new section ex-
plains how crowd patches can be used to generate unlimited populated environ-
ments.
Crowdsimulationisdependentontheenvironment,whichmeansthatthisenvi-
ronment has to be modelled in a specific way. Chapter 8 discusses how to model
such informed environments including terrains and buildings. It also shows how
ontologiescanplayanessentialroleincrowdsimulation.
Preface ix
The last Chapter is dedicated to applications and case studies like crowds in
VirtualheritageandSafetysystems.WehaveaddedanewSectionontherevivalof
thePompeiicityandanotheronimmersionincrowds.
Some crowd requirements along with strategies and techniques that can be
adoptedtodealwiththese,aredescribedinthisbook.Someofthetopicspresented
arerelatedtopopulationmodelling,virtualhumananimation,computervisiontech-
niquesfocusingon crowdcontrolandcrowdrendering,andsomeapplicationsare
analysed.
Acknowledgements The authors would like to thank to Springer and Matheus
Ruschelforsupportinthetextedition.
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 RequirementsandConstraintsforCrowdModeling . . . . . . . . 2
1.2 CrowdSimulationAreas . . . . . . . . . . . . . . . . . . . . . . . 3
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 State-of-the-Art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 CrowdDynamics . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 SociologicalModelsofCrowds . . . . . . . . . . . . . . . . . . . 10
2.3 CrowdSimulation . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.4 BehavioralAnimationofGroupsandCrowds. . . . . . . . . . . . 12
2.5 CrowdManagementTrainingSystems . . . . . . . . . . . . . . . 15
2.6 GroupBehaviorinRoboticsandArtificialLife . . . . . . . . . . . 16
2.7 EnvironmentModelingforCrowds . . . . . . . . . . . . . . . . . 16
2.7.1 EnvironmentModels. . . . . . . . . . . . . . . . . . . . . 16
2.7.2 PathPlanning . . . . . . . . . . . . . . . . . . . . . . . . 17
2.7.3 CollisionAvoidance . . . . . . . . . . . . . . . . . . . . . 19
2.8 CrowdRendering . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.9 CrowdsinNon-real-timeProductions . . . . . . . . . . . . . . . . 22
2.10 CrowdsinGames . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.11 CrowdScenarioAuthoring . . . . . . . . . . . . . . . . . . . . . 24
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3 ModelingofPopulations . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2 CreativeMethods . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.3 BodyShapeCapture . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.4 InterpolatedTechniques . . . . . . . . . . . . . . . . . . . . . . . 34
3.5 AModelforGenerationofPopulation . . . . . . . . . . . . . . . 36
3.5.1 DefinitionoftheInitialData . . . . . . . . . . . . . . . . . 38
3.5.2 ChoiceofaTemplate . . . . . . . . . . . . . . . . . . . . 38
3.5.3 DefinitionofNewSomatotypes . . . . . . . . . . . . . . . 38
xi
xii Contents
3.5.4 CalculationofInfluenceofSampleSomatotypes . . . . . . 39
3.5.5 CalculationofMeshVariation . . . . . . . . . . . . . . . . 40
3.5.6 BodyParts’Deformation . . . . . . . . . . . . . . . . . . 41
3.5.7 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . 43
3.6 UsingComputerVisiontoGenerateCrowds . . . . . . . . . . . . 46
3.6.1 AModelforGeneratingCrowdsBasedonPictures. . . . . 47
3.6.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.7 CrowdAppearanceVariety . . . . . . . . . . . . . . . . . . . . . 57
3.7.1 VarietyatThreeLevels . . . . . . . . . . . . . . . . . . . 58
3.7.2 ColorVariety. . . . . . . . . . . . . . . . . . . . . . . . . 59
3.7.3 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.8 FinalRemarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4 VirtualHumanAnimation . . . . . . . . . . . . . . . . . . . . . . . . 81
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.2 RelatedWorkinLocomotionModeling . . . . . . . . . . . . . . . 82
4.2.1 KinematicMethods . . . . . . . . . . . . . . . . . . . . . 82
4.2.2 PhysicallyBasedMethods . . . . . . . . . . . . . . . . . . 83
4.2.3 MotionInterpolation . . . . . . . . . . . . . . . . . . . . . 84
4.2.4 StatisticalModels . . . . . . . . . . . . . . . . . . . . . . 86
4.3 PrincipalComponentAnalysis . . . . . . . . . . . . . . . . . . . 87
4.3.1 MotionCaptureDataProcess . . . . . . . . . . . . . . . . 87
4.3.2 Full-CycleModel . . . . . . . . . . . . . . . . . . . . . . 88
4.3.3 MotionExtrapolation . . . . . . . . . . . . . . . . . . . . 90
4.4 WalkingModel. . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
4.4.1 MotionInterpolationandExtrapolation . . . . . . . . . . . 93
4.5 MotionRetargetingandTimewarping . . . . . . . . . . . . . . . . 95
4.6 MotionGeneration . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.6.1 SpeedControl . . . . . . . . . . . . . . . . . . . . . . . . 98
4.6.2 TypeofLocomotionControl . . . . . . . . . . . . . . . . 99
4.6.3 PersonificationControl . . . . . . . . . . . . . . . . . . . 99
4.6.4 MotionTransition . . . . . . . . . . . . . . . . . . . . . . 100
4.6.5 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
4.7 AnimationVariety . . . . . . . . . . . . . . . . . . . . . . . . . . 102
4.7.1 AccessoryMovements . . . . . . . . . . . . . . . . . . . . 103
4.8 Steering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
4.8.1 TheNeedforaFastTrajectoryControl . . . . . . . . . . . 104
4.8.2 TheSeekandFunnelingControllers . . . . . . . . . . . . 105
4.9 FinalRemarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
5 BehavioralAnimationofCrowds . . . . . . . . . . . . . . . . . . . . 111
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
5.2 RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
5.3 CrowdBehavioralModels . . . . . . . . . . . . . . . . . . . . . . 114
Contents xiii
5.3.1 PetroSim’sBehavioralModel . . . . . . . . . . . . . . . . 114
5.3.2 APhysicallyBasedBehavioralModel . . . . . . . . . . . 120
5.4 CrowdsNavigation . . . . . . . . . . . . . . . . . . . . . . . . . 126
5.4.1 RobotMotionPlanning . . . . . . . . . . . . . . . . . . . 127
5.4.2 CrowdMotionPlanning . . . . . . . . . . . . . . . . . . . 129
5.4.3 ADecompositionApproachforCrowdNavigation . . . . . 134
5.4.4 AnHybridArchitectureBasedonRegionsofInterest(ROI) 142
5.5 ACollisionAvoidanceMethodBasedontheSpaceColonization
Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
5.5.1 TheCrowdModel:Biocrowds. . . . . . . . . . . . . . . . 146
5.5.2 ExperimentalResults . . . . . . . . . . . . . . . . . . . . 150
5.6 GazeBehaviorsforVirtualCrowdCharacters . . . . . . . . . . . 157
5.6.1 SimulationofAttentionalBehaviors . . . . . . . . . . . . 158
5.6.2 GazeBehaviorsforCrowds . . . . . . . . . . . . . . . . . 159
5.6.3 AutomaticInterestPointDetection . . . . . . . . . . . . . 160
5.6.4 MotionAdaptation . . . . . . . . . . . . . . . . . . . . . . 161
5.7 FinalRemarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
6 RelatingRealCrowdswithVirtualCrowds . . . . . . . . . . . . . . 169
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
6.2 StudyingtheMotionofRealGroupsofPeople . . . . . . . . . . . 169
6.2.1 CrowdCharacteristics . . . . . . . . . . . . . . . . . . . . 169
6.2.2 CrowdEvents . . . . . . . . . . . . . . . . . . . . . . . . 172
6.2.3 ParametersforSimulatingVirtualCrowdsUsingReal
CrowdInformation . . . . . . . . . . . . . . . . . . . . . 173
6.2.4 SimulatingRealScenes . . . . . . . . . . . . . . . . . . . 173
6.3 SociologicalAspects . . . . . . . . . . . . . . . . . . . . . . . . . 177
6.4 ComputerVisionforCrowds . . . . . . . . . . . . . . . . . . . . 179
6.4.1 ABriefOverviewonPeopleTracking . . . . . . . . . . . 179
6.5 AnApproachforCrowdSimulationUsingComputerVision . . . . 181
6.5.1 UsingComputerVisionforPeopleTracking . . . . . . . . 182
6.5.2 ClusteringofCoherentTrajectories . . . . . . . . . . . . . 184
6.5.3 GenerationofExtrapolatedVelocityFields . . . . . . . . . 185
6.5.4 SimulationBasedonRealData . . . . . . . . . . . . . . . 186
6.5.5 SomeExamples . . . . . . . . . . . . . . . . . . . . . . . 188
6.6 FinalRemarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
7 CrowdRendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
7.2 VirtualHumanRepresentations . . . . . . . . . . . . . . . . . . . 196
7.2.1 HumanTemplate. . . . . . . . . . . . . . . . . . . . . . . 196
7.2.2 DeformableMesh . . . . . . . . . . . . . . . . . . . . . . 196
7.2.3 RigidMesh. . . . . . . . . . . . . . . . . . . . . . . . . . 198
7.2.4 Impostor . . . . . . . . . . . . . . . . . . . . . . . . . . . 198