Dynamic Response for Motion Capture Animation Victor B. Zordan Anna Majkowska Bill Chiu Matthew Fast...

Dynamic Response for Dynamic Response for Motion Capture AnimationMotion Capture Animation

Victor B. ZordanAnna Majkowska

Bill ChiuMatthew Fast

Riverside Graphics Lab University of California, Riverside

OutlineOutline

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

IntroductionIntroduction

• 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 Selection (Motion graphs)(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.

Transition Motion SynthesisTransition Motion Synthesis

• Compute transition motion with two goals:– React in a physically plausible manner consistent with fou

nd motion.– Meet the desired state as closely as possible.

• Compute torques as• [Zordan & Hodgins 2002] - Motion capture-driven simulation

s that hit and react.

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• 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.

ImplementationImplementation

• 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.

ConclusionConclusion

• 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.

QuestionQuestion

Thanks for your listening