Human Muscle Modeling using Generalized Cylinders for Volume Considerationss

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Human Muscle Modeling using Generalized Cylinders
for Volume Considerationss

• SK Semwal
• Bill Watson
• Debra McCullough
• University of Colorado, Colorado Springs

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Topics of Presentation

• Introduction and Background
• Generalized Cylinders
• Volume Considerations
• Results
• Conclusions

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Introduction

• Need
• Long standing research problem
• Generalized cylinders simple and intuitive
• Volume considerations for muscles
• Intersection with adjacent muscles/bones lead to
  suitable deformations

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Previous Work

• Since 1968
• Chen-Zeltzer - Biomechanical
• Badlers work human body
• Nadia and Daniel Thalmann human body
• Semwal and Dows GC Muscle models

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Generalized Cylinders

• Shani and Ballard
• Set of cross sections
• Set of generalized axis
• Dow and Semwal
• Model upper and lower arm using GCs

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Extensions

• Leg Musles
• Polygons. NURBS, Shades choices
• Animation sequences leg exercises
• Tension on the muscles
• Speech recognition front-end
• Models contraction/deformations using volume

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Models

• Femur or thigh bone longest and heaviest bone
  hip to tibia
• Tibia or shin bone next heavy bone transfers
  the weight to ankles from hip
• Fibula parallel to tibia on the outside lateral
  attached to several muscles acts a pulley to
  tendons behind ankle

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Generalized Cylinders

• Model 2D planar contours from Medical Books
  (Tortara, Gardner and Cated
• Define these 2D planar contours along GC axis
• NURBS defined using n points on contours
• Rendered on SGI/OpenGL code

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Intersection Testing and Intersection Resolution

• Use cross sections
• Move the intruding point away from the adjacent
  muscle/bones polygonal area between contours
• Volume
• Two cross sections Aavg (Ai Ai1)/2
• Distance between the two GC-axis point for the
  two cross sections
• Volume between two cross sections Aavg d
• Repeat for all cross sections pair for that GC

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Deformation

• pct_chg (curr_vol - init_vol) / init_vol
• rel_chg (cum_sum (curr_vol - init_vol))/cum_sum
• rel_change acts as a guide based upon tolerance
  in changing the cross section points
• Points next to bone and other muscle not modified

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Results

• Precise timing can be achieve
• Smoothing introduces lag

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Results
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Summary

• GC model provided a good method for modeling
  bones and muscles
• Volume considerations allow good deformation
  effects
• Biomechanical analysis and animation

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Future Work

• Model animations
• Realistic biomechanical based rendering
• Automatic detection from CT data and creating GCs

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End