Real-Time Dynamic Wrinkles

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Real-Time Dynamic Wrinkles

• Caroline Larboulette
• Marie-Paule Cani
• GRAVIR Lab, Grenoble, France

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Motivations
Static wrinkle

• Animated wrinkles
• Important for realism
• Cloth
• Skin
• Currently painful under MAYA
• Key shapes
• Deformers
• Aims
• Real-time for computer games
• Applicable to a coarse animated mesh
• Easy to set up

Dynamic wrinkles
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Previous Work

• Bump mapping Blinn78, Boissieux00,
  Pasquariello01
• Efficient but undeformed silhouette
• Physically-based approaches Wu94-99,
  Boissieux00
• Very realistic but slow
• Predefined Wrinkles Viaud92
• Specific mesh incorporating wrinkles
• Displacement mapping Volino99, Hadap99, Bando02
• The user designs the wrinkle pattern

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Our Wrinkling Tool

• Basic Idea
• skin/cloth wrinkle because they tend to maintain
  area
• Physically-based simulation, geometric
  constraints sauvage04 ?
• Aims
• Fast approximation of constant surface
• No manual design of the wrinkles shapes
• Provide control of location and main direction of
  wrinkles
• Our solution
• A constant length wrinkling curve
• Controls the mesh deformation in a region of
  influence

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Wrinkling Curve

• 2D discrete curve of constant length
• Different propagation schemes
• Control of frequency, width of the bumps

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Set up of the Wrinkling Tool

• Draw a line segment
• End points are anchored to the mesh
• Specify a region of influence
• Points under the green rectangle
• Choose an attenuation profile

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Mesh Deformation

• Mesh animated by standard skinning
• Wrinkles updated just before rendering
• Algorithm
• Update 2D curve due to length changes
• Refine mesh if needed
• Compute mesh vertices displacements
• Height given by the coordinate along the curve
• Weighted according to the attenuation profile

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Levels of Details

• Combination of bumps at different scales
• Absorbs compression at different resolutions

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Multi-Wrinkles

• Combination of several wrinkles

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Results forehead wrinkles
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Results joint wrinkles
Without our tool
With our tool
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Results wrinkles on clothes
Back
Front
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• Video and demo

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Conclusion

• Procedural technique
• Mesh refined on the fly
• Could depend on other parameters (camera)
• Easy-to-use for animators
• Use of any existing skinning animation
• Intuitive parameters and visual feedback
• Geometric constraints (length preservation)
• Increases realism
• Real-Time

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Future Work

• Curved Wrinkles
• Collision detection
• Combination with a dynamic flesh model

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Thanks ... Questions ?