Dynamic Response for Motion Capture Animation

Document Sample
Dynamic Response for Motion Capture Animation Powered By Docstoc
					 Dynamic Response for Motion
     Capture Animation


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


•   Introduction
•   Motion Selection
•   Transition Motion Synthesis
•   Implementation
•   Conclusion
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.
• 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.
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:
• 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.
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.
• Timing is critical to make the character’s 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.
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.
• 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.
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.
      Question

Thanks for your listening