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Photorealistic Rendering of Rain Streaks

Photorealistic Rendering of Rain Streaks . Kshitiz Garg Shree K. Nayar . Department of Computer Science Columbia University . SIGGRAPH Conference July 2006, Boston, USA Sponsors: NSF, ONR. A Rain Scene from “The Matrix Revolutions”. A Rain Scene from “The Matrix Revolutions”.

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Photorealistic Rendering of Rain Streaks

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  1. Photorealistic Rendering of Rain Streaks Kshitiz Garg Shree K. Nayar Department of Computer Science Columbia University SIGGRAPH Conference July 2006, Boston, USA Sponsors: NSF, ONR

  2. A Rain Scene from “The Matrix Revolutions”

  3. A Rain Scene from “The Matrix Revolutions” Frame 1 Frame 2 Frame 3

  4. Rendering Streaks using Simple Brightness Model Commercial Software Heuristic-based [Starik and Werman 03] ATI ToyShop Demo [N. Tataturschuk et al. 05] Hybrid-Spectral Method [Langer et al. 04]

  5. Rendering Streaks using Hand Drawn Textures Frame from “The Matrix Revolutions” Hand Drawn Textures Original Image Courtesy Warner Bros. Original Image Courtesy Andy Lomas

  6. Study of Visual Appearance of Rain Streaks • Rain Streak Appearance Model • Rain Streak Texture Database • Image-Based Rain Rendering Algorithm

  7. Oscillations in a Rain Drop [Beard and Kubesh 1989 Andsager et al. 1992] Turbulent Flow of air Turbulent Flow of air A Falling Rain Drop

  8. Oscillations in a Rain Drop [Beard and Kubesh 1989 Andsager et al. 1992] Oblate-Prolate Mode Transverse Mode Oscillations in a Rain Drop

  9. Appearance of a Rain Drop Specular Reflection N Refraction Internal Reflection

  10. Appearance of aNon-OscillatingRain Drop N Non-Oscillating Rain Drop Instant Time Shots Falling Drop Rain Streak

  11. Appearance of anOscillatingRain Drop N Oscillating Rain Drop Instant Time Shots Falling Drop Rain Streak

  12. Rain Streak Appearance Model [Beard and Kubesh 1989 Andsager et al. 1992] Shape of Rain Drop: ? ? Oblate-Prolate Mode Transverse Mode Fall Direction fdrop = (00 – 3600) Not Rotationally Symmetric

  13. Measurement of Rain Streak Appearances Experimental Setup Lighting and Viewing Configuration Drop generator Height: 15 m qlight = (500, 900, 1300) flight = (100 , 300,…, 1700) qview = (700, 900, 1100) y,ydrop Oscillation Parameters qlight qview (A2,0 A3,1 fdrop) =(10 images per light & view) x fdrop flight xdrop -z

  14. 110 90 Estimating the Oscillation Amplitudes qview 90 70 qlight 130 50 50 50 130 130 90 90 flight 130 10 70 30 10 150 30 10 110 50 170 30 170 90 110 50 130 30 Measured Estimation Result Oscillation Amplitudes:

  15. 110 90 Comparison of Actual vs. Rendered Rain Streaks qview 90 70 qlight 130 50 50 50 130 130 90 90 flight 130 10 70 30 10 150 30 10 110 50 170 30 170 90 110 50 130 30 Measured Rendered

  16. Rain Drop Size Source and Camera Distance Camera Parameter Precomputed Database of Streak Textures Factors Affecting the Appearance Render Offline (Database) Lighting and Viewing Direction Oscillations Parameters Render Online (Algorithm) Database contains 6300 HDR Rain Streak Textures (400 MB) ( Publicly available: Please send email torainstreaks@cs.columbia.edu)

  17. Render Streak Appearance Perspective Effects Scale Rotate Camera and Rain Parameters + Raindrop Distribution and Trajectories Using Particle System Camera Effects Light Source Properties Exposure Crop/ Blend Defocus Blur Coarse Depth Map Rain Rendering Pipeline Render Novel Streak Textures User Input Rain Dynamics Streak texture (Source 1) Streak texture (Source n) + Streak texture (Ambient) Scene Image/Video With Rain Scene Image/Video Rain Streak Database

  18. Rendered Rain with Varying Light Direction -150o 150o Light Source Direction

  19. Constant Brightness Streak Model

  20. Comparison with Constant Brightness Model Streak Appearance Model Constant Brightness Model -150o 150o Light Source Direction

  21. Night Scene with Isotropic Source Coarse Depth Map Image of the Scene

  22. Night Scene with Isotropic Source Rendered Rain

  23. Night Scene with Isotropic Source Defocus Effects

  24. Scene with Colored and Anisotropic Sources Coarse Depth Map Scene with Multiple Sources

  25. Scene with Colored and Anisotropic Sources Rendered Rain

  26. Scene with Colored and Anisotropic Sources Streak Appearance Model Constant Brightness Model

  27. Scene with Changing Sky Illumination Input Scene Video

  28. Scene with Changing Sky Illumination Rendered Rain

  29. A Scene with Moving Light Sources Input Scene Video

  30. A Scene with Moving Light Sources Rendered Video

  31. Future Extensions • Real-time Implementation of Rendering Algorithm • Incorporating the Effects of Wind and Turbulence

  32. Summary Rain Streak Appearance Model Rain Streak Texture Database ( Publicly available:rainstreaks@cs.columbia.edu ) Image-Based Rain Rendering Algorithm

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