Evolution & Measurement of BRDFs in Computer Graphics: Empirical Models to Reflectance, Slides of Computer Graphics

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Advanced Graphics

Measuring BRDFs, physically-based

Weathering

First: Parallax

Photography

Ke Colin Zheng , Alex Colburn , Aseem Agarwala ,Maneesh Agrawala , David Salesin , Brian Curless ,Michael F. Cohen, Parallax photography: creating 3Dcinematic effects from stills,

Proceedings of Graphics

Interface 2009

Graphics Interface Video

Last week: Time-varying

BRDF

Time varying BRDF?: reflectance changes over time

Examples: ripening fruits & leaves, weathering, rust

This week

Lights and materials have evolved historically

1970’s: Empirical models (trial-and-error)

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Phong’s illumination model

1980s:

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Physically based models

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Microfacet models (e.g. Cook Torrance model)

1990’s

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Physically-based analytic models of specific effects (weathering,dust, etc)

Early 2000’s

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Measurement & acquisition of static materials/lights (wood,translucence, etc)

Late 2000’s

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Last week: Measurement & acquisition of time-varying BRDFs(ripening, etc)

Exactly What Can We Capture?

1. Appearance
2. Appearance
3. Geometry
4. Geometry
5. Reflectance & Illumination3. Reflectance & Illumination
6. Motion
7. Motion

Static BRDF Measurement

developments

Stephen R. Marschner, Stephen H. Westin, AdamArbree, and Jonathan T. Moon. , Measuring andModeling the Appearance of Finished Wood,Siggraph 2005

Question: What is anisotropic BRDF?

SIGGRAPH VIDEO

Earlier work on Patinas

A Sense of Time (ref: Dorsey and Hanrahan, SIGGRAPH 1996)

Physically-based modeling of

weathering developments

Y. Chen, L. Xia, T. Wong, X. Tong, H. Bao, B. Guoand H. Shum, "Visual Simulation of Weathering byGamma-Ton Tracing" ACM Siggraph 2005

SIGGRAPH VIDEO