Motion Capture in 3D Animation

1
Motion Capture in 3D Animation

• Edward Tse

2
Motion Capture as a Tool

• Motion capture (MOCAP) is an effective 3D
  animation tool for realistically capturing human
  motion

3
Outline

• Rotoscoping
• The MOCAP Pipeline
• Limitations of MOCAP
• The Future of MOCAP

4
Rotoscoping
History

• Captured Video

Johnston, et al., 1995
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Rotoscoping

• History

• Tracing

Johnston, et al., 1995
6
Rotoscoping

• Post Processing

Johnston, et al., 1995
7
The MOCAP Pipeline

• Calibration
• Capture
• 3D Position Reconstruction
• Fitting to the Skeleton
• Post Processing

8
Capture
Costa-Sousa, M., 2004
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Calibration
Image Space World Space
(X,Y) (X,Y,Z)
(X,Y) (X,Y,Z)
(X,Y) (X,Y,Z)
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3D Position Reconstruction (Utopia)
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3D Position Reconstruction (Reality)
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Multiple Markers

• For small number of markers Size
• Occlusions are a problem
• Multiple Hypothesis Tracking

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Multiple Markers

• Mechanical Optical Hybrids

http//www.animazoo.com/services/gypsyHybrid.htm
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Fitting to the Skeleton

• Utopian approach
• 10 20 length changes
• Markers on both sides
• Joint Displacement
• Use Rotation Angles Only

15
Post Processing

• Motion Editing
• Cut, Copy, Paste
• Motion Warping
• Speed up or Slow Down
• Rotate, Scale or Translate
• Motion Signal Processing
• Smoother Motions

16
Limitations of MOCAP

• Subject to data inaccuracy
• Expensive

Device Cost for Body capture (USD)
Mechanical 20000 30000
Electromagnetic 100000 120000
Optical 90000 210000
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Limitations of MOCAP

• Only realistic motion captured
• Cartoony Animations not possible
• WYSIWYG (what you see is what you get)
• Cant add more expression
• Continally need to recapture motion

Robertson, B., 2001
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The Future of MOCAP

• Markerless MOCAP
• Cheaper MOCAP
• MOCAP as Input to Large Displays

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Conclusion

• Motion capture (MOCAP) is an effective 3D
  animation tool for realistically capturing human
  motion

20
References

• Johnston, O., Thomas, F., (1995) The Illusion of
  Life Disney Animation, Disney Editions, ISBN
  0786860707
• Costa-Sousa, M. (2004) Motion Synthesis,
  Powerpoint Presentation
• Parent, R. (2002) Computer Animation Algorithms
  and Techniques, Morgan Kaufmann Publishing
• Ringer, M., Lasenby, J. (2002) Multiple
  Hypothesis Tracking for Automatic Optical Motion
  Capture, European Conference on Computer Vision
  (ECCV 02)
• Robertson, B. (2001) Medieval Magic, Computer
  Graphics World, April 2001.
• Tse, E. (2004) The Single Display Groupware
  Toolkit, MSc Thesis, University of Calgary, Ab,
  Canada
• Bregler, C., Loeb, L., Chuang, E., Deshpande, H.,
  (2002) Turning to the Masters Motion Capturing
  Cartoons, Proceedings of ACM Siggraph 2002 pp 399
  407.
• vicon.com, inition.co.uk, polhemus.com,
  wikipedia.org, animazoo.com, hollywoodjesus.com

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Bonus Slides

• Stuff thats too cool for you!

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Stats
Input Device Frame Rate Range (hz) Position Accuracy Orientation Accuracy Latency range Maximum Points tracked Use in Movies Cost Range (USD)
Polhemus (Magnetic) 60-240 .03in RMS static 0.00015in at 12in range .15 RMS static 0.0012 at 12in range 3.5ms 5 ft 16 Woody and Hamm in Toy Story, The Chandelier in Beauty and the Beast 8495 - 21925
Vicon (Optical) 166-10000 1/117600in or 0.02 of a Pixel up to 4MP No camera limit 500 Sony, Nintendo, Microsoft, Boeing, 89170 - 209920
Ascension ReActor 2 (Magnetic) 100 0.08cm RMS at 1.52m range 0.5 RMS at 1.52m range 4.11m x 4.11m area 30 99,410 - 102315
Gypsy (Mechanical) wireless possible 12-120 No Absolute position 1 200m 42 20000 - 27000
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Calibration
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Outline

• History
• Motion Capture Pipeline
• Limitations
• Future Work