A Physically-Based Particle Model of Emergent Crowd Behaviors

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A Physically-Based Particle Model of Emergent
Crowd Behaviors

• Laure Heïgeas, Annie Luciani,
• Joelle Thollot, Nicolas Castagné
• ICA INPG
• ARTIS-GRAVIR/IMAG INRIA

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The agora of Argos

• Center of the social life
• A visitor should have a
  feeling of this
• We need to put people
  walking around during our walkthrough session
• CG research question how to animate a crowd and
  to render it in real time ?

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What kind of crowd

• We focus on collective behavior
• One character has to avoid others and buildings
• We try to produce some emergent behaviors flows,
  files, groups
• We need a generative model

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State of the art

• Three main approaches
• Kinematic key frames and interpolations preset
  the animation
• Agent systems agents are managed in real time by
  rules of behavior defined with automata
• Particle-based system particles are animated in
  real time by the application of different forces
• Particle systems seem to be well adapted
  generative and simple, no need for special rules

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Our methodology

• Analysis of the dynamic of a crowd
• Dynamic structures
• Traffic jams
• Flows
• Queues
• Obstacle avoidance
• Distance around obstacles apparent volume
• Distance around people psychophysical volume

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Our methodology

• Synthesis of the dynamic effects
• One character one particle on a 2D ground
• Building several particules
• Elastic interaction, piecewise linear
• Thresholds given by the analysis

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Results

• 2D visualization of the trajectories

 
Avoidance of two persons passing face to face
The red discs form a queue and the green ones jam
together
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3D visualization

• NPR style
• Coherent with the style of the scene
• Historical references for the costumes
• Real-time rendering
• Each character is a billboard
• We texture it with a movie of a walking person
  20 points of view and 8 different characters

Loscos et al. 02
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Conclusion

• Results
• Reproduction of complex dynamic behaviors
• Simple interaction model between pairs of objects
• 3D real-time visualization
• Future works
• Allowing the user to interact with the crowd
• real-time simulation
• Anisotropic model of a character front/back