Behavior

1
Behavior
2
Autonomous Characters

• Self-Directed characters
• "puppets that pull their own strings" -Ann
  Marion

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Autonomous Characters

• Acknowledgement
• Much of this material is taken from the work of
  Craig Reynolds. He maintains a web pages
  including a rich source of material of steering
  behavior and the consumate source on flocking.
• Also see
• Steering Behaviors For Autonomous Characters
• by Craig Reynolds

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Three-Tier Hierarchy

• Action selection
• goals and strategies What to do
• Steering
• guidance / motion control How to do it
• Locomotion
• movement generation Getting it
  done

5
Flocks in Film

• 1987 Stanley and Stella in Breaking the Ice,
  (short)
• Director Larry Malone, Producer
  Symbolics, Inc.
• 1988 Behave, (short)
• Produced and directed by Rebecca Allen
• 1989 The Little Death, (short)
• Director Matt Elson, Producer Symbolics,
  Inc.
• 1992 Batman Returns, (feature)
• Director Tim Burton, Producer Warner
  Brothers
• 1993 Cliffhanger, (feature)
• Director Renny Harlin, Producer Carolco.
• 1994 The Lion King, (feature)
• Director Allers / Minkoff, Producer
  Disney.

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Flocks in Film

• 1996 From Dusk Till Dawn, (feature)
• Director Robert Rodriguez, Producer
  Miramax
• 1996 The Hunchback of Notre Dame, (feature)
• Director Trousdale / Wise, Producer
  Disney.
• 1997 Hercules, (feature)
• Director Clements / Musker, Producer
  Disney.
• 1997 Spawn, (feature)
• Director Dipp?, Producer Disney.
• 1997 Starship Troopers, (feature)
• Director Verhoeven, Producer Tristar
  Pictures.
• 1998 Mulan, (feature)
• Director Bancroft/Cook, Producer Disney.

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Flocks in Film

• 1998 Antz, (feature)
• Director Darnell/Guterman/Johnson,
  Producer DreamWorks/PDI.
• 1998 A Bugs Life, (feature)
• Director Lasseter/Stanton, Producer
  Disney/Pixar.
• 1998 The Prince of Egypt, (feature)
• Director Chapman/Hickner/Wells, Producer
  DreamWorks.
• 1999 Star Wars Episode I--The Phantom Menace,
  (feature)
• Director Lucas, Producer Lucasfilm.
• 2000 Lord of the Rings the Fellowship of the
  Ring (feature)
• Director Jackson, Producer New Line Cinema.

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Seeking and Fleeing

• Seeking and Fleeing Applet (Reynolds)

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Pursuing and Avoiding

• Pursuing and Avoiding Applet (Reynolds)

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Separation Avoid Collisions
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Alignment
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Flocking Demos

• Flocking Applet (Craig Reynolds)
• Fish Schooling (Steve Hughes)
• Beach House (Ishihama Yoshiaki )
• For more demos see Reynolds Boids in Java

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Do People Flock?
Social psychologists report the people tend to
travel as singles or in groups of size 2 to 5.
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Characteristics of Groups

• Proximity
• Coupled Behavior
• Common Purpose
• Relationship Between Members

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Moving Formations

• Pairs Side by side
• Triples Triangular shape

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Stationary Formations
Stationary quintuple formed
Moving pair approaches stationary triple
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Locomotion Model for Walking

• Two Parameters
• Speed
• Combination of step length and step rate
• Orientation
• Head direction for forward walking

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Action Space
Accelerate Accelerate
Accelerate Turn Left No Turn
Turn Right Coast
Coast Coast Turn Left
No Turn Turn Right Decelerate
Decelerate Decelerate Turn
Left No Turn Turn Right
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Distributed Preference Voting

• Delegation of voters Constraint Proxies
• Proxies vote on each cell of the action space
• Votes are tallied
• Winning cell represents best compromise among
  competing interests

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Vote Tabulation
Pursuit Point Tracking
Maintain Target Velocity
Inertia
1.0
Avoid Peds
Maintain Formation
Avoid Obstacles
1.0
1.0
Centering
4.0
2.0
5.0
2.0
Electioneer
Winning Cell
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A Group of Two Following a Path
Pursuit Point Tracking
Maintain Formation
walkway axis
-1.0 -1.0 1.0 -1.0 -1.0 1.0 -1.0 -1.0
1.0
1.0 1.0 1.0 -1.0 -1.0 -1.0 -1.0 -1.0
-1.0
pursuit point ?
2.0
1.0
1.0 1.0 3.0 -3.0 -3.0 -1.0 -3.0 -3.0
-3.0
Election for ped 1
?
ped 2
?
ped 1
Winning vote Accelerate/Turn Right
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Avoiding an Obstacle -- Trajectory
walkway axis
walkway axis
ped 1
ped 1
ped 2
ped 2
Small look-ahead distance
Large look-ahead distance
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Interaction Between Pairs -- 1
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Interaction Between Pairs -- 2
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Interaction Between Pairs -- 3