1. Crowd Simulation (INFOMCRWS) - UU Crowd Simulation Software
Wouter van Toll
November 20, 2017

2. INFOMCRWS: UU Crowd Simulation Software
Goals of this session
Understand the various crowd simulation levels
Get an overview of our simulation software
Prepare for Assignment 2
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

3. INFOMCRWS: UU Crowd Simulation Software
But first...
Where are we on Assignment 1?
Anything still unclear?
Deadline on Friday(!)
Please fill in the team schedule, so I can prepare Blackboard
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

4. Recap + Overview Algorithms in a crowd simulation framework
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

5. Crowd simulation framework
Towards Believable Crowds: A Generic Multi-Level Framework for Agent Navigation
Paper B of the course
Our software focuses on levels 4/3/2
Geometric components
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

6. INFOMCRWS: UU Crowd Simulation Software
4: Global path planning
We use the Explicit Corridor Map (ECM)
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 23, 2018
INFOMCRWS: UU Crowd Simulation Software

7. ECM implementation GPU “Exact”: Boost, VRONI, CGAL? November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

8. INFOMCRWS: UU Crowd Simulation Software
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: improvement by Jaklin et al. (2013)
Supports weighted regions
Better smoothness/ shortcut control
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

9. INFOMCRWS: UU Crowd Simulation Software
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 23, 2018
INFOMCRWS: UU Crowd Simulation Software

10. Demo time The ECM framework in action November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

11. INFOMCRWS: UU Crowd Simulation Software
Demos
ECM
Single agent
Crowd
Circle
Unity3D
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

12. 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
Geometric algorithms are painful to implement
Good enough for a paper ≠ 100% robust
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

13. Implementation details
Crowd simulation in the ECM framework
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

14. INFOMCRWS: UU Crowd Simulation Software
Simulation step
performStep(Δt)
For each character: path following
Update pointers along indicative route
Update 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 23, 2018
INFOMCRWS: UU Crowd Simulation Software

15. INFOMCRWS: UU Crowd Simulation Software
Simulation loop
Repeatedly call performStep(Δt)
Possible approach: do as many steps as possible
Use time between frames as step size
Use FPS to measure efficiency
We use a fixed time step (0.1 s)
Use computation time to measure efficiency
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
Is this a good idea?
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

16. Performance (without visualization)
1 thread
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

17. Performance (without visualization)
8 threads
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

18. INFOMCRWS: UU Crowd Simulation Software
DLL / Plug-in
We built a DLL for our software
API with ~50 functions (C)
Environment modelling
Simulation setup
Simulation: add/remove characters, set goals, ...
Unity plug-in
C# wrapper around API functions
Grouped into logical objects (Unity scripts)
GUI
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

19. INFOMCRWS: UU Crowd Simulation Software
Update in development
Different version of the simulation loop
DLL still does most of the simulation, except updating the positions
DLL sends velocities to Unity
Unity computes new positions
You can apply physics there
Higher framerate than our framework
Unity sends positions back to DLL
Available soon
Hopefully late November / early December
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

20. INFOMCRWS: UU Crowd Simulation Software
Your turn
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

21. INFOMCRWS: UU Crowd Simulation Software
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!
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

22. INFOMCRWS: UU Crowd Simulation Software
Things to keep in mind
DLL uses a slow version of dynamic updates
Faster method is not yet robust enough
Don’t use “removable obstacle” for fast-moving things
Recommended to use 2D environments
A single layer, everything visible from above
Height differences are OK
Unity does not like multi-threading very much
Manually set the number of available threads?
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

23. INFOMCRWS: UU Crowd Simulation Software
Getting started
Install Unity 5.x
(if you already have Unity 2017, that’s probably OK)
Sign EULA
Clone our git repository
Unity project with scripts and UUCS DLL
Follow the tutorial
Mostly GUI-related
Bonus challenges, useful for Assignment 2
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software

24. INFOMCRWS: UU Crowd Simulation Software
Extra sessions
Support hours
Wednesday
Nov 29, Dec 6, Dec 13, Dec 20, Jan 10, Jan 17
Locations: see website
Mid-term session
December 13,
Give a demo / progress report
November 23, 2018
INFOMCRWS: UU Crowd Simulation Software