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Announcements

Final project presentations will take place on Wednesday with each group having 10 minutes. Final reports are due on Friday at 11:59pm. Please place PowerPoint presentations in the artifact directory. Evaluation will be done at the end of class today.

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Announcements

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  1. Announcements • Final project presentations on Wednesday • Each group has 10 minutes • Place .ppt talk in artifact directory • Final reports due on Friday at 11:59pm • Web page (see project4 web page) • Does not have to be long, but should be sufficient to describe what you did, related work, results, and discussion • Evals at the end of class today

  2. Matting and Transparency Slides adapted from Alexei Efros, Yung-Yu Chuang, and Shree Nayar

  3. How does Superman fly? • Super-human powers? • OR • Image Matting?

  4. Forrest Gump (1994) Digital matting

  5. B F C C foreground color alpha matte background plate composite F compositing equation =0 B Compositing

  6. B F C C composite F compositing equation =1 B Compositing

  7. B F C C composite F compositing equation =0.6 B Compositing

  8. B  F C compositing equation observation Matting

  9. B  F C compositing equation Three approaches: 1 reduce #unknowns 2 add observations 3 add priors Matting

  10. B C B  F difference matting Matting (reduce #unknowns)

  11. F C B blue screen matting Matting (reduce #unknowns)

  12. Problems with color difference Background color is usually not perfect! (lighting, shadowing…)

  13. F C B Smith & Blinn, 96 Matting (add observations)

  14. C B BG FG unknown  B F Ruzon-Tomasi rotoscoping Natural image matting Matting (add priors)

  15. alpha trimap input

  16. input composite

  17. Environment Matting and Compositing Video Douglas E. Zongker ~ Dawn M. Werner ~ Brian Curless ~ David H. Salesin

  18. Fast Separation of Direct and Global Images Using High Frequency Illumination Michael D. Grossberg City College of New York Shree K. Nayar Gurunandan G. Krishnan Columbia University Ramesh Raskar MERL SIGGRAPH Conference Boston, July 2006 Support: ONR, NSF, MERL

  19. participating medium B D A C A : Direct B : Interrelection E C : Subsurface translucent surface D : Volumetric E : Diffusion Direct and Global Illumination surface source P camera

  20. j global BRDF and geometry radiance direct Direct and Global Components: Interreflections surface source i camera

  21. i + fraction of activated source elements High Frequency Illumination Pattern surface source camera

  22. i - + High Frequency Illumination Pattern surface source camera fraction of activated source elements

  23. Separation from Two Images direct global

  24. j i Other Global Effects: Subsurface Scattering translucent surface source camera

  25. j i Other Global Effects: Volumetric Scattering participating medium surface source camera

  26. Diffuse Interreflections Specular Interreflections Diffusion Volumetric Scattering Subsurface Scattering

  27. Scene

  28. Direct Global Scene

  29. Real World Examples: Can You Guess the Images?

  30. Direct Global Eggs: Diffuse Interreflections

  31. Direct Global Wooden Blocks: Specular Interreflections

  32. Direct Global Kitchen Sink: Volumetric Scattering Volumetric Scattering: Chandrasekar 50, Ishimaru 78

  33. Direct Global Peppers: Subsurface Scattering

  34. Direct Global Hand Skin: Hanrahan and Krueger 93, Uchida 96, Haro 01, Jensen et al. 01, Cula and Dana 02, Igarashi et al. 05, Weyrich et al. 05

  35. Direct Global Direct Global Face: Without and With Makeup Without Makeup With Makeup

  36. Direct Global Blonde Hair Hair Scattering: Stamm et al. 77, Bustard and Smith 91, Lu et al. 00 Marschner et al. 03

  37. www.cs.columbia.edu/CAVE

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