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Simulating Crowds Simulating Dynamical Features of Escape Panic & Self-Organization Phenomena in Pedestrian Crowds. Papers by Helbing Presented by Thiago Ize. Why do we care?. Easy to use when doing crowds For the layman animator For the sleep deprived programmer
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Simulating CrowdsSimulating Dynamical Features of Escape Panic & Self-Organization Phenomena in Pedestrian Crowds Papers by Helbing Presented by Thiago Ize
Why do we care? • Easy to use when doing crowds • For the layman animator • For the sleep deprived programmer • Lots of goodies come for free • Escape panic features • Faster-is-slower effect • Crowding around doorway • Mass behavior • Normal pedestrian traffic features • Lanes • Waiting at doors • Braking rules
The model Missing the ! pushes αaway from all pedestrians, β closest part of static things, Β, thatαshould avoid gets α to desired velocity, pushes αtowards certain pedestrians, i These use potential force fields
What are potential force fields? • Field around an object that exerts a force on other objects • Used by roboticists exponential square directional
The model – normal condition • Lots of room for choice of potential function • Helbing uses an elliptical directional potential directional Directional potential: Gradient: α β α α Force applied on αby β:
What does that do? • Lane formation • Potential force behind leader is low • Leader is moving away (force is not increasing) • Turn taking at doorways (it’s a polite model) • Easy to follow someone through the door. • Eventually pressure from other side builds up and direction changes • Rudimentary collision avoidance
Panic !! • People are now really close together • Body force – counteracts bodily compression • Sliding friction force – people slow down when really close to other people and things • Desired speed, , has increased • Switch from directional to exponential potential field (but would probably still work with directional)
The model - panic condition Exponential potential field body force sliding friction force g() = 0 if α and βare not touching, otherwise = distance from α to β tangential velocity difference normal from βto α
What does that do? • Faster-is-slower effect • Sliding friction term • High desired velocity (panic) • Squishes people together • Gaps quickly fill up • Exits get an arch-like blockage
Integrating panic with normality • Sliding friction and body term can safely be used in all situations • Would probably make all scenes look better • Panic occurs when everyone’s desired velocity is high and points to same location
Mass behavior • Confused people will follow everyone else average direction of neighbors j in a certain radius Ri individual direction panic probability
Problems • Possible to go through boundaries • Can be fixed by increasing force of boundary • Sometimes good • Excels at crowds, not individual pedestrian movement • When focus is on big crowds and not on individuals, this is good.