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Image-Based Lighting II

Image-Based Lighting II. 15-463: Rendering and Image Processing Alexei Efros. …with a lot of slides donated by Paul Debevec. Reach for the sky. How can we capture the whole sky as an environment map? What happens with the sun?. Direct HDR Capture of the Sun and Sky.

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Image-Based Lighting II

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  1. Image-Based Lighting II 15-463: Rendering and Image Processing Alexei Efros …with a lot of slides donated by Paul Debevec

  2. Reach for the sky • How can we capture the whole sky as an environment map? • What happens with the sun?

  3. Direct HDR Capture of the Sun and Sky • Use Sigma 8mm fisheye lens and Canon EOS 1Ds to cover entire sky • Use 3.0 ND filter on lens back to cover full range of light • Only 0.1% of light gets through! Stumpfel, Jones, Wenger, Tchou, Hawkins, and Debevec. “Direct HDR Capture of the Sun and Sky”. To appear in Afrigraph 2004.

  4. Extreme HDR Image Series 1 secf/4 1/4 secf/4 1/30 secf/4 1/30 secf/16 1/250 secf/16 1/1000 secf/16 1/8000 sec f/16

  5. Extreme HDR Image Series- sun closeup 1 secf/4 1/4 secf/4 1/30 secf/4 1/30 secf/16 1/250 secf/16 1/1000 secf/16 1/8000 sec f/16only image that does not saturate!

  6. Spectral Calibration – ND filters are NOT Necessarily Neutral! Before correction After correction based on MacBeth ColorChecker chart appearance

  7. Two Complete days of HDR Lighting (day averages at 1 min. intervals) Feb 22, 2004 Feb 23, 2004

  8. HDRI Sky Probe

  9. Clipped Sky + Sun Source

  10. Lit by sky only

  11. Lit by sun only

  12. Lit by sun and sky

  13. Illuminating a Small Scene

  14. We can now illuminatesynthetic objects with real light. How do we add synthetic objects to a real scene?

  15. Real Scene Example • Goal: place synthetic objects on table

  16. Light Probe / Calibration Grid

  17. light-based model real scene Modeling the Scene

  18. The Light-Based Room Model

  19. light-based model local scene synthetic objects real scene Modeling the Scene

  20. distant scene (light-based, unknown BRDF) The Lighting Computation synthetic objects (known BRDF) local scene (estimated BRDF)

  21. Rendering into the Scene • Background Plate

  22. Rendering into the Scene • Objects and Local Scene matched to Scene

  23. Differential Rendering • Local scene w/o objects, illuminated by model

  24. Differential Rendering (2)Difference in local scene - =

  25. Differential Rendering • Final Result

  26. IMAGE-BASED LIGHTING INFIAT LUX Paul Debevec, Tim Hawkins, Westley Sarokin, H. P. Duiker, Christine Cheng, Tal Garfinkel, Jenny Huang SIGGRAPH 99 Electronic Theater

  27. HDR Image Series 2 sec 1/4 sec 1/30 sec 1/250 sec 1/2000 sec 1/8000 sec

  28. Stp1 Panorama

  29. Assembled Panorama

  30. Light Probe Images

  31. Capturing a Spatially-Varying Lighting Environment

  32. Identified Light Sources

  33. The Movie

  34. Simulating the Glare in the Human Eye • Greg Spencer, Peter Shirley, Kurt Zimmerman, and Donald Greenberg. Physically-based glare effects for digital images. SIGGRAPH 95.

  35. Scattering in the eye What’s the scattering model?

  36. HDR Image

  37. Gaussian Blur, LDR information Only

  38. Gaussian Blur, Full HDR Information

  39. Full HDR Disc Blur

  40. Frame Postprocessing in Rendering with Natural Light

  41. Compositing Complex Objects

  42. Rendering Light Probes as Light Sources 1999

  43. A Lighting Reproduction Approach

  44. Composited Results

  45. Environment Map from Single Image?

  46. Eye as Light Probe! (Nayar et al)

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