1. Workshop II UU Crowd Simulation Framework
Wouter van Toll
Angelos Kremyzas
Path Planning course
December 7, 2016

2. Workshop II: UU Crowd Simulation Framework
Goals of this session
Understand the various crowd simulation levels
Get an overview of our simulation software
Prepare for Assignment 2
November 26, 2018
Workshop II: UU Crowd Simulation Framework

3. Workshop II: UU Crowd Simulation Framework
Algorithms in a crowd simulation framework
THeory
November 26, 2018
Workshop II: UU Crowd Simulation Framework

4. Crowd simulation framework
Towards Believable Crowds: A Generic Multi-Level Framework for Agent Navigation
Paper #1 of the course
Our software focuses on levels 4/3/2
Geometric components
November 26, 2018
Workshop II: UU Crowd Simulation Framework

5. Workshop II: UU Crowd Simulation Framework
4: Global path planning
We use the Explicit Corridor Map
Compact navigation mesh
Supports any character radius
Multi-layered environments
Dynamic updates
Other options could also work
As long as characters can compute an indicative route
November 26, 2018
Workshop II: UU Crowd Simulation Framework

6. Workshop II: UU Crowd Simulation Framework
3: Path following
Smoothly follow a desired path
Input: indicative route, non-smooth indication of the path
In each simulation step, compute an attraction point
Leads to a preferred velocity for the next level
Indicative Route Method (IRM, 2009)
MIRAN (#7): improvement by Jaklin et al. (2013)
Supports weighted regions
Better smoothness/shortcut control
November 26, 2018
Workshop II: UU Crowd Simulation Framework

7. Workshop II: UU Crowd Simulation Framework
2: Local movement
Roughly move in the preferred direction, while...
...responding to collisions with other characters
...avoiding future collisions
...adapting to the surrounding streams of people
...maintaining social group behavior
etc.
November 26, 2018
Workshop II: UU Crowd Simulation Framework

8. Paper vs. Implementation
It’s hard to judge a method in practice
Not all parameter settings are described in a paper
Lots of details are up to the programmer
Some necessary hacks are not mentioned
Small changes can have huge impacts
November 26, 2018
Workshop II: UU Crowd Simulation Framework

9. Workshop II: UU Crowd Simulation Framework
The ECM framework in action
Demo time
November 26, 2018
Workshop II: UU Crowd Simulation Framework

10. Workshop II: UU Crowd Simulation Framework
Demos
ECM
Single agent
Crowd
Circle
Unity3D
November 26, 2018
Workshop II: UU Crowd Simulation Framework

11. Workshop II: UU Crowd Simulation Framework
Crowd simulation in the ECM framework
Implementation
November 26, 2018
Workshop II: UU Crowd Simulation Framework

12. Workshop II: UU Crowd Simulation Framework
Simulation step
Core of the crowd simulation engine
performStep(Δt)
Increase total time by Δt
For each character: path following
Update pointers along indicative route (if any)
Compute new attraction point, preferred velocity
For each character: collision avoidance
Compute new velocity vNew
Smoothen vNew (optional)
Compute collision forces F (optional)
For each character
Update velocity: v := vNew + Δt · F/mass
Update position: p := p + Δt · v
Update nearest-neighbor data structure
(There are actually many more substeps)
Why separate loops?
Order of characters does not matter
Characters are independent, each loop can be parallellized
November 26, 2018
Workshop II: UU Crowd Simulation Framework

13. Workshop II: UU Crowd Simulation Framework
Simulation loop
Update the simulation per time step: performStep(Δt)
Possible approach: do as many steps as possible
Use time between frames as step size
Use FPS to measure efficiency
Is this a good idea?
We use a fixed time step (0.1 s)
Use computation time to measure efficiency (e.g. % of step time)
Behavior does not depend on the framerate
Fast-forward by calling performStep() more/less often
You really don’t need a higher simulation framerate
Visualization framerate can be much higher
November 26, 2018
Workshop II: UU Crowd Simulation Framework

14. Workshop II: UU Crowd Simulation Framework
Assignment 2
Create a game in Unity that uses our crowd simulation software as a plug-in
Solve at least one problem you’ve seen in Assignment 1
Write a report about your solutions
Bonus points if the game is original, fun, etc.
Also an experiment for us!
Test usability of the UUCS plug-in
Tutorial
November 26, 2018
Workshop II: UU Crowd Simulation Framework