Dynamic Response for Motion Capture Animation

1
Dynamic Response for Motion Capture Animation

• Victor B. Zordan
• Anna Majkowska
• Bill Chiu
• Matthew Fast
• Riverside Graphics Lab University of California,
  Riverside

2
Outline

• Introduction
• Motion Selection
• Transition Motion Synthesis
• Implementation
• Conclusion

3
Introduction

• General adaptation and re-use of the data is
  limited by the available techniques for editing
  and modifying data in controllable ways.
• Physical models commonly used to responsivity to
  characters by generating modifications.
• But, the effects of an impact are over, there are
  no general schemes to move the simulation in a
  meaningful way and return the simulation to
  motion capture control.

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• Automatically computes a dynamic reaction to an
  unanticipated impact and returns the character to
  an available motion from a capture repository for
  the remainder of the dynamic response to the
  interaction.
• Two critical components
• Search engine compares initial simulated response
  with reaction segments from a motion library.
• Joint-torque controller that actuates the
  simulation to reach the desired posture.

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Motion Selection (Motion graphs)

• Creating response
• Find transition-to motion capture sequence form
  repository.
• Compare simulated data with sequences in motion
  library.
• Define sample frame as vector
• Distance D between windows is defined as

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• To capture the dynamic properties.
• Assign high weights to the trunk parts.
• Reduce the problem of sliding ground contact.
• To increase the efficiency of the search function
• Pre-process database to find unique frames.

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Transition Motion Synthesis

• Compute transition motion with two goals
• React in a physically plausible manner consistent
  with found motion.
• Meet the desired state as closely as possible.
• Compute torques as
• Zordan Hodgins 2002 - Motion capture-driven
  simulations that hit and react.

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• Timing is critical to make the characters action
  appear realistic.
• Generating and blending motion capture data
• Interpolation to remove remaining disturbances.
• Interpolate linearly the root node offset.
• For rotation, interpolates by slerp quaternion.
• Using simple linear weighting.

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Implementation

• To create believable exchanges between
  characters.
• Heavy impact-based interactions require
  simulation of both the recipient and the
  deliverer of the impacts generated.
• Simply following the completely simulated motion
  for a small number of frames after the impact.
• Then blending back to the same original motion
  through interpolation lead to a convincing attack
  motion.

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• Motion capture reactions
• Pushed were made from the front, side and back
  with reaction including balanced recovery that
  required minimal foot repositioning.
• Range of such responses starting from a single
  pair of motion clips found by simply varying the
  facing direction of one of the characters.

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Conclusion

• Takes advantage of the concept of the described
  burst following an impact without the need for a
  complicated implementation.
• Important contribution is use of a controller
  acts in accordance with the upcoming motion.
• Avoid an unconscious look for the character.

12
Question

• Thanks for your listening