Author Archives: 01 Rachel Tobe

Particle Simulation in Human Behavior

Jillian Blakey, Rachel Tobe, Jen Bray

Particle Simulation in Human Behavior

To approach a discussion on simulating human behavior through particles, we first defined particle simulation.  We collectively decided that particle simulation is a realistic portrayal of the physical influences and the movement of a particle through a series of obstacles.  These particles are often representative of more complex natural beings such as water, smoke, or humans.

We began our research in human behavior simulation through the exploration of programs and modeling systems that we have been exposed to in architecture.  Programs such as Maya, Rhino, and 3dsMax are conducive to particle simulation.  They have the ability to apply physical forces either inherently programmed or with a plug-in that has been since developed.  It quickly became apparent that the use of these programs to represent human motion was superficial. The bouncing or rolling balls did not include enough variables to account for human randomness.  You can read more about the extent of these modeling programs in Jillian’s paper found here:

The concept of the unpredictability of humans began a discussion on crowd behavior in panic situations and optimizing egress patterns for safety.  This drew a lot of attention after the collapse of the World Trade Center in New York City.  Researchers in building code and safety regulation began asking how we can accurately predict crowd response to such events ( ).  These are issues that are far more complex than the force of gravity applied to a sort of body.  As Paul Torrens, an associate professor in the School of Geographical Sciences at Arizona State University, explains:

“Crowds are complex, adaptive systems that may seem chaotic but have an underlying order. They self-assemble in time and space and exhibit geometric patterns based on layer upon layer of human-to-human and human-to-environment interactions. They are almost impossible to model realistically.”

To explain to our fellow classmates the true complexity of these algorithms, we decided it was necessary to describe in very basic terms the science behind the simulation.  Theories and mathematical concepts and fields such as game theory, fluid dynamics and force dynamics were to be the focus of this description.  To help with some of the explanation of these concepts we decided to use two descriptive videos produced by the GAMMA group.  The summarization of the science behind the simulations is given in more detail through Rachel Tobe’s passage below:

Through further research, we discovered several academic and professional groups that are mathematically addressing this issue of human complexity in modeling.  The Geometric Algorithms for Modeling, Motion, and Animation (GAMMA) Group at the University of North Carolina and the Fire Safety Engineering Group with the School of Computing & Mathematical Sciences at the University of Greenwich are constantly researching new algorithms and modeling systems that bring us closer to realistic crowd representation.

After reviewing the science, we chose to investigate how two independent companies developed their own human behavior particle simulation software.  We evaluated them for legibility of interface, ease of use, customization abilities, and analytical data available.  These two programs included the software called Simwalk and buildingEXODUS.

What we discovered was an inherent difference in function between these two programs.  Simwalk, we hypothesized, was designed to be used by designers because it advertises to be very easy to use.  Unfortunately, we did not get the chance to fully test this as the free download of Simwalk had some serious glitches in it.  The free download for buildingEXODUS, while still not at its fullest potential, was a download that allowed us to play with the program and tweak some of the controls.  Because we were able to actually begin to use buildingEXODUS, we decided to use Youtube videos to give an idea of what Simwalk is meant to be like and what it’s potential could be.   We then decided it would be best to break down the buildingEXODUS program because its founders the Fire Safety Engineering Group have spent a significant amount of time finding and including the many variables that make up an emergency situation.

For this reason, we found that buildingEXODUS is a great tool for more detailed analysis of evacuations.  In being able to adjust where fires start, where exits are blocked, and what building materials are used, the architect or designer is better able to visualize the worst possible scenario, see the potential death toll and make adjustments to their design.  For a more comprehensive look into this program see the following research paper:

Project B Particle Simulation and Crowd Movement Presentation


Videos Used:

Fluid Dynamics and Force Dynamics:

Repetition and Alteration of Variables:

Simwalk Simulations:

Project B: Particle Simulation and Human Path Finding, the Science and Math Behind It

Particle Simulation on its most basic level is a simulation that realistically portrays the influences of gravity and the movement of a particle through a series of obstacles.  This particular application renders particle simulations to be useful for few studies including rough flight pattern analysis, water flow analysis, and wind analysis.  However, some scientists and computer programmers such as those at SimWalk and the Fire Safety Engineering Group have realized the potential for particle simulations and their application toward graphing and analyzing human movement.  Using research on crowd flight patterns, these scientists have been able to make these particles more realistic, even assigning different “personalities” to them.  This allows for more accurate analysis of floor plans and could give designers a much better insight into emergency evacuation plans.

How does this great technology work?  What is the science behind how this works?  To explain this, an explanation of theoretical physics and mathematics is needed.

When code writers first began theorizing how to best write a script to accurately portray human movement they decided to apply game theory.  The definition for game theory, as defined by Merriam Webster, is: “the analysis of a situation involving conflicting interests (as in business or military strategy) in terms of gains and losses among opposing players.”  Game theory has been extensively researched and played with in Mathematics, Sociology, and Psychology.  However, the issue with game theory is that it attempts to rationalize human behavior to a strict set of rules.  For this reason, the first attempts at modeling human behavior in a computer-generated environment were largely false.

Once this was discovered, many code writers began to explore alternative equations and theories.  The most advanced of which attempted to simulate the psychological state of the agents by creating various subroutines.  These subroutines have the agent make decisions based on a variety of factors including the following:


Coupling these behavior models with well-designed physical models using fluid and force dynamics to simulate the movement people and their response to their environments, simulations can come close to replicating real behavior.  Fluid Dynamics is the study of fluid movement through a space.  Calculating such movement requires an analysis of the variables that impact fluid dynamics including but not limited to: boundary conditions, volume forces, pressure, and vicious stress (  Force Dynamics is a study of “how entities interact with respect to force.  Included here is the exertion of force, resistance to such a force, the overcoming of such a resistance, blockage of the expression of force, removal of such blockage and the like” (

If treated as a flow analysis, the movement of crowds can be incredibly similar to the flow of water.  However, this use of fluid dynamics alone is not enough.  The human factor of psychology and sociology must also be applied because it is well known that people do not necessarily always flow to the nearest exit.  The addition of force dynamics helps with calculating what would be a perceived rational route for a crowd.

To test this the creators of the simulation will take real world footage of a crowd or evacuation and replicate the conditions in the simulation. They then test the simulations output compared to the actual output. By continually tweaking individual values they eventually reach a point where the simulation output and real world output match.  Such trial and error proceedings are perfectly portrayed in the following video by GAMMA (Geometric Algorithms for Modeling, Motion, and Animation) research group in the Department of Computer Science at the University of North Carolina at Chapel Hill.

The study of crowd flow, fluid dynamics, and force dynamics have become the foundation for the codes running the simulations of human path and particle simulation.  This is one model of many, and the each code or equation always needs further testing to reach more life-like results.  The complexity of situations and crowd mentalities further makes this research and code writing difficult and therefore puts into question the true value of particle simulations.  While they have significantly advanced over the years, true path movement in emergency situations is still hotly debated amongst programmers.

Presentation Board Draft – Sharon Luu, Jenn Bray, Amos Dudley, Rachel Tobe 01

Visualization – 01 Tobe, Luu, Bray, Dudley

The flexibility of this design will enable us to alter the curves to better suit the lights, and explore the benefits of material, spacing, and acoustic quality.

With the wavy form of the cork offset slightly, the impression of this ceiling detail is that of movement and fluidity.  This form nicely juxtaposes the rhythm of the space.  However, to work with the space, further adjustment is needed in spacing and depth of these panels.


Elisa Strozyk, an artist and furniture designer, is also the creator of “wooden textiles”, a fabric made out of small pieces of wooden geometry.  Each piece of “fabric” is made by adhering small pieces of wood to a thin cloth in a geometric pattern.  This is done to both sides of the cloth to help provide stability when the cloth is crinkled.  This technique provides great flexibility to the form and also provides an interesting and dynamic surface.  However, the fluid nature of this method has many advantages and disadvantages.

It would provide a great visual experience were it used on a large scale.  The purity of the geometric forms juxtaposed against the inconsistency and erratic crinkling of the form is an exciting visual experience.  A further benefit to this construction form is the potential use for it in acoustics.  Rather than have large pieces of panels that reflect sound back down into the room, we should consider breaking up the panels, using softer materials, and giving ourselves the opportunity to adjust our design.

The main problem with this design and it’s potential application to our future assignment: it will be difficult, as it is, to use in a ceiling system or wall system because it might not hold its form well in either of these configurations.  As a wall, it would require a second support system underneath.  As a ceiling panel system, we would have to do some research to see if it is even possible harden the form before we suspend it.  However, as you can see below it is possible to do this.