A Crash Course on Texturing

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A Crash Course on Texturing

• Li-Yi Wei
• 2005
• at Tsinghua University, Beijing

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What is texturing
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Overview of texturing

• Texture generation
• You need to get the texture first
• Texture map
• You need to figure out how to wrap the texture
• Texture sampling
• You need to avoid artifacts
• GPU texturing issue
• You need to do this fast

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Texture generation

• Draw by hand
• ?flexible
• ? easy to control
• ?requires artistic skills
• ?mostly looks artificial

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Texture generation

• Photography
• ?easy to deploy
• ?realistic image
• ?curvature problem small patch
• ?lighting/shadowing/distortion problem

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Texture generation

• Texture synthesis
• ?flexible
• ?easy to deploy
• ?general
• ?arbitrarily large result
• ?difficult to design a good algorithm!

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Texture synthesis

• Procedural synthesis
• Example-based synthesis

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Procedural synthesis

• Synthesize texture by procedural code
• ?compact
• ?full control
• ?no resolution limit
• ?not easy to author
• ?limited category

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Procedural synthesis examples
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Perlin noise
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Perlin noise examples
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Example-based synthesis

• Synthesis from example
• ?general
• ?easy to use
• ?limited resolution
• ?need good algorithm

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Example-based synthesis

• Huge literature
• I will only talk about recent work
• Pixel-based synthesis
• Patch-based synthesis
• Optimization

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Pixel-based synthesis

• Synthesize pixels based on neighborhood
• Efros Leung 1999 Wei Levoy 2000

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Pixel-based synthesis examples
Oriented
Random
Regular
Semi-regular
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Pixel-based synthesis failures
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Patch-based synthesis

• Liang et al 2001 Efros Freeman 2001

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Patch-based synthesis examples
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Comparison
input
pixel-based
patch-based
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Texture mapping

• How to map a 2D texture onto a 3D surface?
• Minimal distortion
• No discontinuity
• It is not easy! Try to wrap a paper around a ball

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Texture mapping methodology

• Huge literature, I will only cover
• Volume texture
• Surface synthesis
• Texture atlas
• Base-domain parameterization

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Volume texture

• Surround the object with 3D volume
• ?no distortion nor discontinuity
• ?mainly for isotropic textures
• ?large storage
• ?GPU unfriendly
• ?natural for procedural synthesis

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Surface synthesis

• Extend 2D synthesis to 3D surface
• Either pixel or patch based
• ?minimal distortion, no discontinuity
• ?anisotropic patterns
• ?only applies to one object/texture combination

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Texture atlas

• Divide the surface into planar patches
• ?popular approach
• ?GPU friendly
• ?seam and distortion

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Base-domain parameterization

• MAPS Lee et al 1998
• Parameterize based on coarse mesh
• ?less distortion/discontinuity than atlas
• ?less straightforward for GPU

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Base-domain parameterization

• Poly-cube maps 2004
• Use multiple cubemaps
• ?minimal distortion, no discontinuity
• ?can be done on GPU

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Texture sampling
Aliasing
Anti-aliasing
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Aliasing,1D case
Aliasing
No aliasing
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Aliasing, 2D case
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Aliasing, 2D case
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Isotropic versus Anisotropic filtering
isotropic
anisotropic
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Anisotropic filtering implementation

• Ripmap

• Multiple probes

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Texturing on GPU

• Model geometry as texture
• Bump map, displacement map, VDM
• Texture caching and compression

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VDM

• View-dependent displacement map Wang et al 2004

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VDM result
bump
horizon
displacement
VDM
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Sphere marching

• GPU Gems II chapter 8

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Texture compression

• DXT
• ? simple and fast
• ?limited compression ratio (81)

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Tile-based texturing on GPU

• Wei 2004
• ?big compression
• ?limited to homogeneous pattern
• ?can look repetitive

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Conclusion

• Look at the course paper for more details
• References
• Exercises
• Potential future work

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