Real-Time Fur on Arbitrary Surfaces

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Real-Time Furon Arbitrary Surfaces

• Jed Lengyel
• Emil Praun
• Adam Finkelstein
• Hugues Hoppe

Microsoft Research Princeton University Princeton
University Microsoft Research
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Real-Time CG Needs Fuzzy Objects

• Name your favorite things almost all of them are
  fuzzy.

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Motivation
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Tarantula Demo
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Previous work on fur

• Particle systems Reeves 83
• Volume textures Kajiya Kay 86
• Special surface shader Goldman 97
• Geometry Van Gelder Wilhelms 97
• Volume textures using CG Hardware
• Meyer and Neyret 98
• Lengyel 00

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Geometric Models

• Cones ? too slow on current hardware
• Lines ? interactive for sparse fur
• Poor filtering

Van Gelder, Wilhelms 97
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Previous work on fur

• Volume textures using CG hardware
• Meyer and Neyret 98
• Shell textures Lengyel 00

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Shell textures
Lengyel 00
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Generating the Textures
Lengyel 00

• Geometric model
• Seed surface with curl starting points.
• Grow as particle system.

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Generating the Textures
Lengyel 00
Interpolate to generate more seed points.
Ignore hair-to-hair collision.
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Generating the Textures
Lengyel 00
2. Sample volumeKeep color opacity
(normal)
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Generating the Textures
Lengyel 00
Wide range of fur possible with different seed
colors and curl parameters
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Problems with shell textures

• (1) Surface parametrization
• (given arbitrary surface)?
• (2) Texture memory usage
• (several shells,over entire surface,at hair
  resolution!)

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Problems with shell textures

• (3) Poor silhouettes
• (shells break apart at oblique angles)

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Review of Lapped Textures
texture patch
surface
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Key Idea Patch Pasting
texture patch
lapped textures
surface
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Stone Bunny Demo
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Stone Bunny Result
25 frames per sec!
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Lapped volume textures

• Simple idea each shell is a lapped texture.

opaque skin
transparent shells
composite
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Bunny Demo
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Issues

• Rendering order
• innermost ? outermost shell
• Directional texture vs. isotropic texture
• Texture alpha
• Lapped textures splotch outline
• Volume is semi-transparent
• ? alpha splotch outline volume alpha

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Poor silhouette
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Fins
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Fin Texture
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Fin rendering

• Rendering order skin shells fins
• shells, fins no Z buffer write!
• Fade based onviewing angle

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Fin Demo
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Interactive Controls

• Hair color
• Hair length
• Hair direction (combing)

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Combing Demo
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Demos
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