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Acquiring Scattering Properties of Participating Media by Dilution SIGGRAPH Conference

Acquiring Scattering Properties of Participating Media by Dilution SIGGRAPH Conference July 2006, Boston, USA Sponsors: NSF, ONR, Sloan. Srinivasa Narasimhan Mohit Gupta Carnegie Mellon University. Ravi Ramamoorthi Shree Nayar Columbia University. Craig Donner Henrik Wann Jensen

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Acquiring Scattering Properties of Participating Media by Dilution SIGGRAPH Conference

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  1. Acquiring Scattering Properties of Participating Media by Dilution SIGGRAPH Conference July 2006, Boston, USA Sponsors: NSF, ONR, Sloan Srinivasa Narasimhan Mohit Gupta Carnegie Mellon University Ravi Ramamoorthi Shree Nayar Columbia University Craig Donner Henrik Wann Jensen UC San Diego

  2. Scattering in Participating Media Accurate Rendering of Media Critical for Realism

  3. Significant Progress in Volumetric Rendering [Jensen et al, 01] [Donner, 03] [Fedkiw et al, 01] [Jensen, 02] Accuracy Limited by the Input Medium Parameters

  4. Measurement Work in Graphics Attenuation of Laser Beams [Hawkins et al, 05] No Scattering Directional Scattering using a Mirror [Hawkins et al, 05] No Attenuation Diffusion-based BSSRDF Measurement [Jensen et al, 01; Joshi et al, 05] High Scattering

  5. Measurement Work in Graphics Attenuation of Laser Beams [Hawkins et al, 05] No Scattering Directional Scattering using a Mirror [Hawkins et al, 05] No Attenuation Diffusion-based BSSRDF Measurement [Jensen et al, 01; Joshi et al, 05] High Scattering One Simple Setup Robust Parameter Estimation from a Photograph Cover Entire Parameter Space

  6. Our Measurement Setup Camera Glass Tank

  7. Frosted Glass Bulb Anti-reflection Glass Our Measurement Setup Dimensions of Tank: 25cm x 30 cm x 30 cm

  8. Problem: Multiple Scattering • Causes significant Blurring of • Incident Light • Inverse Estimation is Ill-conditioned • and Not Unique [Ishimaru 75,97; McCormick et al., 79-83] Photo of Milk in Setup

  9. Problem: Multiple Scattering • Causes significant Blurring of • Incident Light • Inverse Estimation is Ill-conditioned • and Not Unique [Ishimaru 75,97; McCormick et al., 79-83] Photo of Milk in Setup • Key Idea: Avoid Multiple Scattering At “low” concentrations: - Single Scattering dominant - Multiple Scattering negligible [Ishimaru 97; Narasimhan et al 99-03] Increasing Milk Concentrations

  10. So…dilute media “sufficiently” with water to simplify light transport.

  11. Medium Source Physical Apparatus • Range of Scattering Angles: [ 0 deg, 175 deg ] • Range of Path-lengths: [ 125 mm, 610mm ] • All Path-length and Angle Combinations Captured Ortho-Photo

  12. Medium Source • Image Formation Model: Scattering Coefficient Phase function Extinction Coefficient

  13. Medium Source • Image Formation Model: Scattering Coefficient Phase function Extinction Coefficient • Parameter Estimation: Nelder-Meade Search in Matlab

  14. Medium Source • Image Formation Model: Scattering Coefficient Phase function Extinction Coefficient Unique and Robust! • Parameter Estimation: Nelder-Meade Search in Matlab

  15. How Much to Dilute? 20 ml 4 ml 9 ml 15 ml 18 ml 23 ml 26 ml Increasing Milk Concentration Single Scattering Multiple Scattering 26 ml Single Scattering Multiple Scattering 15 ml 9 ml

  16. Database of 40 Common Materials • Alcoholic Beverages – 3 wines, 3 beers… • Coffees – black, with cream, cappuccino,… • Milks – chocolate, whole, 2% fat, vitamin A & D,… • Juices – grape, apple, cranberry,… • Soft-drinks – coke, pepsi, lemonade… • Cleaning supplies – detergents, shampoos,… • Powders and Crystals – sugar, salt, tang,… • Pacific Ocean Water – bay, different depths,…

  17. Gatorade Budweiser Coors Light Yuengling Beer Era Detergent Clorox Detergent Orange Powder Pink Lemonade Lemon Tea Cappuccino Espresso Mint Mocha Suisse Mocha Coke Pepsi Sprite Apple Juice Ruby Gfruit Juice Grape Juice Cranberry Juice Sugar Powder Merlot Chardonnay White Zinfandel Low Fat Choc Milk Reg Choc Milk Low Fat Milk Reduced Milk Regular Milk Low Fat Soy Milk Reg Soy Milk White Gfruit Juice Mission Bay (10ft, 8 hrs) Mission Bay (10ft, 30 mins) Mission Bay (Surface, 1 hr) Pacific Ocean (Surface, 1 hr) Salt Powder Heads & Shoulders Balancing Shampoo Strawberry Shampoo

  18. Sample Photographs: Highly Scattering Media Pink Lemonade Powder Regular Chocolate Milk Low Fat Choc Milk Ruby Grapefruit Juice Salt Powder Orange Powder Low Fat Milk Espresso Coffee Cappuccino Powder Regular Milk

  19. Sample Photographs: Highly Absorbing Media Coke Yuengling Beer Pacific Ocean Water Grape Juice Merlot Wine Era Detergent Chardonnay Wine Strawberry Shampoo Lemon Tea Powder Brown Sugar

  20. Sample Parameters: Highly Scattering Media

  21. Sample Parameters: Highly Absorbing Media

  22. Merlot Wine • Coke • Era Detergent • Orange Powder Absorption Coefficient • Pink Lemonade Powder • Strawberry Shampoo • Ruby Grape Fruit Juice • Regular Choc Milk • Chardonnay • Regular Milk • Coors Light • Ocean Water • Low Fat Choc Milk • Low Fat Milk • Sprite Scattering Coefficient

  23. Highly Scattering Media • Merlot Wine • Coke • Era Detergent • Orange Powder Absorption Coefficient • Pink Lemonade Powder • Strawberry Shampoo • Ruby Grape Fruit Juice • Regular Choc Milk • Chardonnay • Regular Milk • Coors Light • Ocean Water • Low Fat Choc Milk • Low Fat Milk • Sprite Scattering Coefficient

  24. Highly Absorbing Media • Merlot Wine • Coke • Era Detergent • Orange Powder Absorption Coefficient • Pink Lemonade Powder • Strawberry Shampoo • Ruby Grape Fruit Juice • Regular Choc Milk • Chardonnay • Regular Milk • Ocean Water • Coors Light • Low Fat Choc Milk • Low Fat Milk • Sprite Scattering Coefficient

  25. Low Scattering & Absorption • Merlot Wine • Coke • Era Detergent • Orange Powder Absorption Coefficient • Pink Lemonade Powder • Strawberry Shampoo • Ruby Grape Fruit Juice • Regular Choc Milk • Chardonnay • Regular Milk • Ocean Water • Coors Light • Low Fat Choc Milk • Low Fat Milk • Sprite Scattering Coefficient

  26. Moderate Scattering & Absorption • Merlot Wine • Coke • Era Detergent • Orange Powder Absorption Coefficient • Pink Lemonade Powder • Strawberry Shampoo • Ruby Grape Fruit Juice • Regular Choc Milk • Chardonnay • Regular Milk • Coors Light • Low Fat Choc Milk • Low Fat Milk • Sprite Scattering Coefficient

  27. R Intensity (0-255) G B Distance from the Source (mm) Experimental Validation: Fits to Measurements Orange Powder

  28. Sample Fits: Highly Absorbing Media Brightness Dist. from Source Pacific Ocean Surface Water Era Detergent Yuengling Beer Merlot Wine

  29. Sample Fits: Highly Scattering Media Brightness Dist. from Source Regular Milk Low Fat Milk Clorox Detergent Regular Chocolate Milk

  30. Renderings with the “Kitchen” Environment Map [Debevec et al]

  31. Merlot Wine Chardonnay Wine

  32. Coca-Cola • Yuengling Beer

  33. Milk • Yuengling Beer

  34. Renderings with a Single Directional Light Source

  35. Yuengling Beer Coca-cola

  36. Orange Powder Chardonnay Wine

  37. Strawberry Shampoo Era Detergent

  38. Blending Parameters + = 75% Espresso 25% Milk Light Coffee

  39. Blending Parameters + = 50% Wine 50% Milk ?

  40. Transitions between Media Wine  Water  Milk  Espresso

  41. Concentrations at which Parameters Measured

  42. Real Concentrations

  43. Summary = + Simple Apparatus Robust Parameter Estimation Render Any Concentration Mixing Media http://graphics.cs.cmu.edu

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