Highly Dynamic Motion Synthesis

1
Highly Dynamic Motion Synthesis

• ACCAD Individual Studies with Matt Lewis
• March 10th, 2005
• Domin Lee

2
Motif

• ACCAD Mocap Lab
• 14 camera VICON8 system
• 3000 sq. foot space
• Kaydaras MotionBuilder 5.1
• Overcome limitations of Mocap system
• Occlusions
• Dynamic Motions
• Etc

3
Our Focus
4
Our Focus

• Capturing highly dynamic motions are hard
• Limited by Actors ability
• Some motions are just impossible
• Need Motion Synthesis
• To generate highly dynamic motions
• But why HIGHLY dynamic motion?

5
Background

• Motion Libraries for Character Animation
• Zoran Popovic
• Synthesis of Complex Dynamic Character Motion
  from Simple animations (2002)
• Style-based Inverse Kinematics (2004)
• Momentum-based Parameterization of Dynamic
  Character Motion (2004)

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Background

• Rigid Body Dynamics
• Ronald Fedkiw
• Animations of rigid bodies
• New Techniques
• Triangulated Surface
• Signed Distance Function
• Time Integration
• Shock Propagation

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Nonconvex Rigid Bodies with Stacking

• 2003
• Videos

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Implementation

• .NET, glut, and OpenGL
• Many resources and documentations
• glut.h
• Replace the following
• extern _CRTIMP void __cdecl exit(int)
• _CRTIMP __declspec(noreturn) void __cdecl
  exit(int)

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Implementation

• For more information http//graphics.stanford.edu
  /papers/rigid_bodies-sig03/
• Demo

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Motion Capture Data

• Mocap data
• Map mocap data to a human figure (doll)
• .BVH or .ASF
• Chose AMC/ASF format
• Demo

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Combining Mocap and Dynamics

• Mapping mocap data in human figures
• 15 ellipses controlled by mocap data
• Demo

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Whats Next?

• Capturing highly dynamic motions
• Football tackling
• Wrestling crossline
• Experiment with agent systems
• Controls secondary behaviors
• Brain controls secondary motions
• Ex) tackling in football

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Current Technology

• Many Popovics implementations
• Endorphin from Natural Motion

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Questions or Comments ?
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Implementation

• Geometric Representation
• A dual representation
• Explicit Triangulated surface
• Supplies point samples on surface.
• Implicit Signed distance function F.
• ? F ? distance to surface, F lt 0 inside, F gt 0
  outside.
• Stored on a uniform or octree grid.
• Constant time inside/outside test.
• Normal ?F (defined throughout space).

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Implementation

• Time Stepping Approach
• A new ordering of the simulation loop
• Process collision
• Update velocity
• Process contact
• Update position
• Traditional approach
• Update pos vel
• Process collision
• Process contact