Motion Blending

1
Motion Blending

• Hyun Joon Shin

2
Contents

• Introduction
• Related work
• Basic ideas
• Representation
• Analysis
• Motion selection
• Time warping
• Posture blending
• Retargeting
• Experiment
• Conclusion
• Future Work

3
Introduction

• Motion Blending

Happy walking
Sad walking
4
Introduction

• Motion Attributes
• Qualitative
• Happy ? Sad
• Clueless ? Knowledgeable
• Energetic ? Disheartened
• ......
• Quantitative
• Speed
• Degree of slope
• Degree of gyration
• ......

5
Related Work

• Motion Interpolation
• Verbs Adverbs Multidimensional Motion
  Interpolation Rose et. al. 1998
• Everything by Example Cohen et. al. 2000

Happy
Clueless
Knowledgeable
Sad
6
Related Work

• Multidimensional Motion Blending
• Scattered data interpolation
• Linear approximation
• Radial basis
• Time warping
• Key time
• Generic time
• Motion transition
• Verb graph
• Sinusoidal function

7
Problems

• Precise Motion
• Qualitative attributes
• Manual attribute specification
• Euler angles representation
• Inaccurate IK solving
• Real-time Dynamic Control
• Time warping problem

8
Basic Ideas

• Precise Qualitative Control
• Motion analysis
• Layered representation
• Quaternion interpolation
• Real-time motion retargeting
• Real-time Dynamic Control
• Incremental time warping
• Real-time motion retargeting

9
Overview
attributes
Motion Selection
Target Character
weights
Motion Analysis
Motion Retargeting
Posture Interpolation
Motion Samples
Target Motion
Attributes Layered Representation
10
Currently, Problem is

• Motion Samples
• Walking, jogging, and running motions
• Gyratory samples for each motion
• Almost regular distribution
• Attributes
• Speed of walking
• Degree of gyration
• ......

11
Motion Representation

• Layered Representation
• 1st layer abstracted body trajectory
• Speed
• Degree of gyration
• Key-times

tk
t1
tn
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Motion Representation

• 2nd layer relative to abstracted trajectory
• Body posture
• Footholds
• 3rd layer relative to foothold
• Foot posture

13
Motion Analysis

• Assumption
• Circular trajectory
• Constant velocity
• The same number of steps
• Speed
• arc length/time
• Degree of Gyration
• gyration/time
• Key-times Hill-Strike Toe-Off
• Manual specification

?
l
14
Motion Selection

• Four Neighbors
• Weight Based on Bilinear Interpolation

speed
right turn
left turn
15
Time Warping

• Generic time Rose et. al. 1998
• Actual time interpolation

Backward !!
W0.5
W0.5
tk
t1
W0.5 ?1
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Time Warping

• Incremental Time Warping
• Blending derivatives
• Finite integration

W0.5
W0.5
tk
t1
W0.5 ?1
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Posture Blending

• 1st Layer
• Exact computation
• 2nd Layer
• Posture blending
• quaternion blending
• Foothold blending
• hill-strike position
• preserve until toe-off
• 3rd Layer
• Quaternion blending

18
Quaternion Interpolation

• Bilinear Interpolation

Spherical Linear Interpolation
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Motion Retargeting

• On-line Motion Retargeting
• Importance-based approach Shin et. al

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Spatial Constraints

• Foothold interpolation
• Ankle position
• Fixed position during stance
• Ankle displacement
• Displacement during stance
• 3rd layer of motion
• Importance
• Distance between
• Ankle position Floor

21
Experiment
22
Conclusion

• Real-time Motion Interpolation
• Qualitative attribute
• Speed gyration
• Dynamic attribute control
• Application
• Game
• Sport replay
• Animation prototyping

23
Future Work

• Motion Set Attributes
• Non-regular samples
• More quantitative Qualitative attributes
• High dimensionality
• Motion Analysis
• Multidimensional interpolation extrapolation !!