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

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