Group Behaviors

Seminal flocking papers Craig Reynolds Flocks, Herds, and Schools: A Distributed Behavioral Model – SIGGRAPH 1987Flocks, Herds, and Schools: A Distributed Behavioral Model – SIGGRAPH 1987 Steering Behaviors for Autonomous CharactersSteering Behaviors for Autonomous Characters MIT BS and MSMIT BS and MS Oscar awarded in 1998Oscar awarded in 1998 EA, Dreamworks, Sony PlaystationEA, Dreamworks, Sony Playstation Craig Reynolds Flocks, Herds, and Schools: A Distributed Behavioral Model – SIGGRAPH 1987Flocks, Herds, and Schools: A Distributed Behavioral Model – SIGGRAPH 1987 Steering Behaviors for Autonomous CharactersSteering Behaviors for Autonomous Characters MIT BS and MSMIT BS and MS Oscar awarded in 1998Oscar awarded in 1998 EA, Dreamworks, Sony PlaystationEA, Dreamworks, Sony Playstation

Components of flocking Three factors influence acceleration Move closer to centroid of local neighborsMove closer to centroid of local neighbors Avoid collisions with closest neighborsAvoid collisions with closest neighbors Maintain same velocity as neighborsMaintain same velocity as neighbors Three factors influence acceleration Move closer to centroid of local neighborsMove closer to centroid of local neighbors Avoid collisions with closest neighborsAvoid collisions with closest neighbors Maintain same velocity as neighborsMaintain same velocity as neighbors

Boid details Some physics f = maf = ma Banking (when turning) is modeledBanking (when turning) is modeled Some logic Averaging acceleration urges leads to problemsAveraging acceleration urges leads to problems –Do nothing when two vectors cancel Prioritized allocation of movements to acceleration urgesPrioritized allocation of movements to acceleration urges –Flock centering could be ignored to avoid an obstacle Some physics f = maf = ma Banking (when turning) is modeledBanking (when turning) is modeled Some logic Averaging acceleration urges leads to problemsAveraging acceleration urges leads to problems –Do nothing when two vectors cancel Prioritized allocation of movements to acceleration urgesPrioritized allocation of movements to acceleration urges –Flock centering could be ignored to avoid an obstacle

Components of flocking Local perception of neighbors Reduces computational complexityReduces computational complexity –n 2 in number of boids otherwise Improves realismImproves realism –React to what you know –Mistakes will happen Local perception of neighbors Reduces computational complexityReduces computational complexity –n 2 in number of boids otherwise Improves realismImproves realism –React to what you know –Mistakes will happen

Local perception of neighbors Xiaoyuan Tu Artificial Fishes: Autonomous Locomotion, Perception, and Behavior, SIGGRAPH 1994 with Demetri TerzopoulosArtificial Fishes: Autonomous Locomotion, Perception, and Behavior, SIGGRAPH 1994 with Demetri Terzopoulos MoviesMovies –Go Fish! –The Undersea World of Jack Coustou AwardsAwards –Only woman ever to win the ACM dissertation award  First Chinese (Tsinghua) and first from Canada as well! Xiaoyuan Tu Artificial Fishes: Autonomous Locomotion, Perception, and Behavior, SIGGRAPH 1994 with Demetri TerzopoulosArtificial Fishes: Autonomous Locomotion, Perception, and Behavior, SIGGRAPH 1994 with Demetri Terzopoulos MoviesMovies –Go Fish! –The Undersea World of Jack Coustou AwardsAwards –Only woman ever to win the ACM dissertation award  First Chinese (Tsinghua) and first from Canada as well!

Other sources for group dynamics Helbing et al. – Escape Panic Helbing et al. – Trails Robotics Maja Mataric Ron Arkin