Crowd Animation Open Software


ChAOS (Crowd Animation Open Software) is an animation tool to create crowds of walking characters from a set of 2D trajectories files generated by your preferred crowd-simulation software.

Most microscopic crowd simulation algorithms generate 2D global trajectories for a set of agents.

However, many applications require to transform this 2D trajectory into full-body walking animations for characters following those trajectories.

ChAOS is based on Unity3D, and will let you easily play with camera positions and make snaphots of the resulting animation. ChAOS is also able to save snapshots at a specific framerate, which can be used to generate videos with tools such as ffmpeg.



In the first scenario of the video, we have two groups of characters of different colors walking in opposite directions. The trajectory of each agent was generated using the EACS simulation algorithms [1] and animated with ChAOS.

This scenario is included in our distribution of ChAOS. If you download the tool, you will find the scenario file ExampleTwoColors.xml in the Scenarios folder. This type of scenario file allows you to set up general parameters:

  • Position and movement of the camera
  • Recording
  • Path to the directory with the trajectory files for each agent
  • Color of the agents

The trajectory files are located in the directory Scenarios/ExampleTwoColors . For each agent, you will find a CSV file describing its trajectory. ChAOS uses only the times and the x and y coordinates in these files.

If your scenario file has recording enabled, running the scenario in ChAOS will cause screenshots to be saved in the directory Output. To convert these images to a video, you can use any third-party software such as ffmpeg. Here is an example of a command to generate a video with ffmpeg:

ffmpeg -r 15 -i Output/img%04d.png -c:v libx264 -vf fps=25 -pix_fmt yuv420p out.mp4


[1] Bruneau, J., & Pettré, J. (2017, December). EACS: Effective Avoidance Combination Strategy. In Computer Graphics Forum (Vol. 36, No. 8, pp. 108-122).


Julien Pettré
Inria Research Scientist
E-mail : julien.pettre[at]

Comments are closed.