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Bart van Greevenbroek. Hierarchical Model for Real Time Simulation of Virtual Human Crowds. Overview. Article Authors ViCrowd Experiments Assessment. The Authors. Soraia Raupp Musse. Daniel Thalmann. The Article. Published in 2001 Cited 229 times
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Bart van Greevenbroek Hierarchical Model for Real Time Simulation of Virtual HumanCrowds
Overview • Article • Authors • ViCrowd • Experiments • Assessment
The Authors SoraiaRauppMusse Daniel Thalmann
The Article • Published in 2001 • Cited 229 times • Cited by “Finding Paths for Coherent Groups Using clearance” (no 6 on our list) by Arno kamphuis and Mark Overmars
Controlling a Crowd • Scripted behaviors • Reactive behaviors • User-guided behaviors
ViCrowd • Behavioral based multi-level framework • Used to simulate crowds in real time • Script-based language.
Knowledge, Beliefs and Intentions • Knowledge (information about the world) • Beliefs (states of emotion) • Intentions (goals)
Events • Can change the knowledge, beliefs or intentions of an agent • And thus the behavior • Example: A door closes, the knowledge that the door closes changes, agents will not go through that door. • Example: A bomb goes off, agents within a radius panic, and behavior is altered.
Main Problems • Modeling of crowd information, also concerning the distribution of groups • Different levels of realism • Required Structure to provide interaction between groups of agents in real time
High level • Flocking • Following • Goal Changing • Attraction • Repulsion • Split • Space adaptability • Safe-Wandering
Flocking • the agents from the same group share the same list of goals; • They walk at similar speeds; • They follow the paths generated as showed • One agent can wait for another on arrival at a goal when another agent from the same group is missing.
Following • A group can follow another group by sharing the same goals, either temporary or permanently.
Goal Changing • Agents can change groups, and this is influenced by the relationship value with each agent in the group (value between 0 and 1) • Agents have a leadership ability value, which is also taken into account • If an agent has a higher relationship with another group, it will join that group. If the leadership value is high enough
Attraction • The user can paint regions where the groups must be at a certain point, and the orientation can be influenced as well. • Groups are normally attracted to attraction points
Repulsion • Groups are repulsed by obstacles and each other (similar to the social force model)
Split • Groups can split randomly
Space Adaptability • The group wants to occupy all the walking space, using a bezier curve:
Safe-Wandering • Using a procedural method, the agents predict collisions using collision detection between two lines
Results (1) • Scripted Behavior (SB) • Reactive Behavior (RB) • Guided Behavior (GB)
Future work • Improving viCrowd script language by integrating Python • Panic and Emergency Behaviors
The Good • High level of compatibility with other methods • Very flexible system • User has control over groups if needed • Groups are essential for a realistic crowd, so its good to focus on groups • Knowledge, Beliefs and Intentions is a well-known paradigm in the AI field
The Bad • Performance is not awe-inspiring • Exact formulae are missing • No system specs are given, which makes comparison with other methods difficult • A collection of simple motions are possible, but what about complex motions? • Seeing as groups follow attraction points, Oscillations can occur.
The ugly • The site with examples they mentioned, does not work. • Figures are sloppy, some text is cut off. • Meaningless pictures. If something is happening in the experiment involving motions, draw arrows or make the motion obvious. • In general, they go all over the place.