« Scale Based Model for the psychology of crowds into virtual environments»

Fabien Tschirhart

ATI – University of Paris VIII Fabien.tschirhart@free.fr

Crowds into virtual environments Different purposes

Video Games Different purposes

Crowds into virtual environments

↑ Hitman Absolution ↓ Supreme Commander ↑ Theme Hospital ↓ Total War : Shogun 2

Crowds into virtual environments Cinema Different purposes

↑ King Kong ↓ The Curious Case of Benjamin Button ↑ Troie ↓ The Mummy : Tomb of the Dragon Emperor

Crowds into virtual environments Simulation Different purposes

↑ SpirOps Crowd ↓ MassMotion ↑ Geppetto ↓ Myriad II

Existing crowd models The macroscopic approach

Macroscopic models assimilates people as a unique mass behaving like a fluid or a gas :

This kind of model was introduced by Henderson in 1971 who identified people as a fluid flowing out in a building.

In 1992, Helbing suggested that people could be acting like gas particles, making a comparison between an individual state and the different states gases have according to the Maxwell-Boltzmann distribution.

←

Myriad II

Existing crowd models The macroscopic approach

This approach was then ehanced with more complex models :

Predtechenshkii and Milinskii suggested a model to estimate the local density of a flow of people and it’s propagation between blocs :

The conflagration model from Takahashi, Tanaka and Kose, cuts infrastructures into different kinds of generic areas, then it computes the maximal time required for the evacuation of each area according to the room obstruction :

Existing crowd models The macroscopic approach

Strenght and weakness :

=> Can be used for sequences with thousands individuals for a low cost.

=> Easy to set up.

=> Very fast to compute.

=> Almost exclusively designed for the simulation of massive evacuations of buildings.

=> Ignore every constraint linked to individual’s behavior.

=> Cannot be used for other purposes such as video game, cinema or any kind of virtual reality application.

Existing crowd models The microscopic approach

Microscopic models focus on the individual, confering him his own characteristics and afterward it’s own decisional aptitude :

First, there was two kind of microscopics models, thoses using particles, and thoses using agents. First were the particles models ; particles were not supposed to have a decisional aptitude, they were just enduring the environnement : always acting the same way in the same situation. The Game Of Life, from Conway, may be the first of them.

Existing crowd models The microscopic approach

Agents can take decision : they are acting. Acting entities are required to simulate or reproduce the behavior of the living. In 1987, Reynolds was probably one of the first to use agents to simulate the behavior of living entities : flock of birds.

Existing crowd models The microscopic approach : major tools

Crowd simulation tools designed for artistic purposes are all based on microscopic models :

- MASSIVE (Multiple Agent Simulation System in Virtual Environment) have been used in numerous famous movies…

Existing crowd models

- Golaem Crowd, a very competitive tool from the french company Golaem.

Donikian. S, 2004, Modélisation contrôle et animation d’agents virtuels autonomes évoluant dans des environnements informés et structurés. HDR. Université de Rennes 1.

Paris. S, 2007, Caractérisation des niveaux de service et modélisation des circulations de personnes dans les lieux d’échanges. Doctoral Thesis. Université de Rennes 1.

The microscopic approach : major tools

Existing crowd models

- Miarmy, a plugin for Autodesk Maya, made by a chinese company : Basefount. It can also handles non-humanoid crowds :

The microscopic approach : major tools

Existing crowd models The microscopic approach : other tools

A few other stand-alone tools or plugins can also be used for crowd simulation into virtual environments :

- EKI One

- Geppetto

- BlenderPeople

- SpirOps Crowd

- …

Crowd psychology The differences between simulation and reality

Working exclusively upon individuals, microscopics models neglects an important phenomenom :

While immersed in a a crowd, individuals follow a whole new set of rules, getting a behavior totally different from the one they have while isolated.

Le Bon, G. 1895. Psychologie des foules. Les presses universitaires de France. English Translation : The Crowd : A Study of the Popular Mind

McPhail, C. 1991. The Myth of the Madding Crowd. Aldine Transaction

Challenger, R., Clegg C., and Robinson, M. 2009. Understanding Crowd behavior – Supporting Evidence. Emergency Planning College, University of Leeds.

Challenger, R., Clegg C., and Robinson, M. 2009. Understanding Crowd behavior – Guidance and lessons identified. Emergency Planning College, University of Leeds.

Crowd psychology The differences between simulation and reality

Major theories about crowd psychology :

- Social Loafing Theory :

This theory point out the fact that, in group, some people will fade away because the importance of their effort seems less perceptible to them. These people will simply let themselves led by others.

This happens with crowds when some people don’t know the path and think others are heading to the same place : they just follow them.

If a path is blocked, a lot of people will just follow others to find their way, without looking by themselves to where they are heading.

Latané, B., Kipling, W., and Harking S. 1979. Many hands make light the work : the causes consequences of social loafing. Journal of personality and social psychology. 37. 822-832.

Crowd psychology The differences between simulation and reality

Major theories about crowd psychology :

- Social Identity model of Deindividuation Effects (SIDE) :

The SIDE model cuts down individuality into social identities. People will act in different manners depending on the social identity they are endorsing.

The same individual, in a public place, will have a different behavior if he is : - A tourist

- Going to work

- Going to an event with friends

- A police force

- A rioter

- …

Reicher, S., Spears, R., and Postmes, T. 1995. A Social identity model of desindividuation phenomena. European Review of Social Psychology. 6. 161-198.

Reicher, S., Levin M. R., and Gordijn, E. 1998. More on desindividuation, power relations between groups and the expression of social identity : Three studies on the effects of visibility to the in-group. British Journal of Psychology. 37. 15-40.

Crowd psychology The differences between simulation and reality

Major theories about crowd psychology :

- Elaborated Social Identity Model (ESIM) :

ESIM concentrates upon interactions between different crowds or groups. It operates if a crowd is in the neighborhood of other crowds and if there is interactions between the two crowds.

It suggests that the interpretation of a crowd does not take into account the real intentions of each crowds. From the action of a crowd will flow the actions of the other crowds, evolving into a chain of actions and reactions.

Drury, J., and Reicher S. 2005. Explaining enduring empowerment : a comparative study of collective action and psychological outcomes. European Journal of Social Psychology. 35. 35-58.

Cronin, P., and Reicher S. 2009. Accountability processes and group dynamics : a SIDE perspective on the policing of anti-capitalist riot. European Journal of Social Psychology. 39. 237-254.

Crowd psychology The differences between simulation and reality

Major theories about crowd psychology :

- Crowd in panic situation:

There are several behavioral approaches specifics to crowds in emergency situation :

- Place Script : people will only use paths they already knows. [1]

- Mass Panic : Excessive fear by and large associated to an utmost selfishness. Generates specitic behavior from the crowd. [2]

- Social identity : Facing the same threat everyone will share the same social identity and so, will give mutual aid despite the lack of anterior affective links [3]

[1] Donald, I., and Canter, D. V. 1992. Intentionality and fatality during the King’s Cross underground fire. Fire and European Journal of Social Psychology. 22. 203-218.

[2] Mawson, A. R. 2005. Understanding mass panic and other collective responses to threat and disaster. Psychiatry. 68. 95-113.

[3] Drury, J., and Reicher S. 2000. Collective action and psychological change : the emergence of new social identities. British Journal of Social Psychology. 39. 579-604.

Scale Based Model A model to handle specific aspects of crowds

Main idea :

Using a microscopic approach, we are suggesting a model that will attributes a different behavior to a same agent, depending on his situation :

All alone

In a group

In a crowd

In a crowd, within other crowds

To do so, we will consider groups and crowds as specific entities with their own characteristics and an influence ability on their members : the individuals.

Scale Based Model A model to handle specific aspects of crowds

Individual :

As an agent, an individual should have the same characteristics we can find in most microscopic based models : - dimensions

- sex

- age

- average speed

- objective

But also, model specific characteristics :

- social identities

- group (if he belongs to a group)

- ease

- mood

Used to determine behavior within/toward a group or a crowd

Scale Based Model A model to handle specific aspects of crowds

Crowds and groups :

As well, crowds and groups should have model specific characteristics :

- social identity

- mood (members average)

- solidity

- size (number of individuals…)

Scale Based Model A model to handle specific aspects of crowds

Influences :

Social identities provide to individuals the ability to proceed to their self-categorization depending on what they perceive from surrounding people.

When many people of the same social ID are close, a crowd can appear.

People outside the crowd will be attracted by the crowd if they have the same social ID.

At a lower degree, the mood will also have an influence on their attraction to the crowd.

Scale Based Model A model to handle specific aspects of crowds

Effects:

Once aligned and integrated to a crowd, an individual will receive influence from the crowd, this influence will change the way he is acting.

Each individual in the crowd will be under the crowd effects until he leaves.

Scale Based Model A model to handle specific aspects of crowds

Living crowd:

The properties of a crowd will evolve depending on its members (individuals).

Its social identity and its average mood will change : attracting more individuals and releasing thoses that are not anymore aligned with the crowd.

It means crowds are dynamic : they can appear or disappear depending on the people.

Scale Based Model

The model is currently being integrated using the Unity Engine®.

The goal is to create a small and easy tool to try the specificities of the Scale Based Model :

Implementation and environment

Scale Based Model

Everything is work in progress and almost all graphic component except the GUI are made of place holders.

Video

« Scale Based Model for the psychology of crowds into virtual environments »

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