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# SIGGRAPH 2012 Computational Plenoptic Imaging Course - 4 Light Fields

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SIGGRAPH 2012 Computational Plenoptic Imaging Course - 4 Light Fields

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### SIGGRAPH 2012 Computational Plenoptic Imaging Course - 4 Light Fields

1. 1. Light Field Acquisition Douglas Lanman NVIDIA Research
2. 2. Introduction to Light Fields
3. 3. The 5D Plenoptic Function P(q, f, l, t)Q: What is the set of all things that one can ever see?A: The Plenoptic Function [Adelson and Bergen 1991] (from plenus, complete or full, and optic)
4. 4. The 5D Plenoptic Function P(q, f, l, t)Q: What is the set of all things that one can ever see?A: The Plenoptic Function [Adelson and Bergen 1991] (from plenus, complete or full, and optic)
5. 5. The 5D Plenoptic Function P(q, f, l, t, px, py, pz )P(q, f, l, t, px, py, pz ) defines the intensity of light:• as a function of viewpoint• as a function of time• as a function of wavelength
6. 6. The 5D Plenoptic Function P(q, f, l, t, px, py, pz )P(q, f, l, t, px, py, pz ) defines the intensity of light:• as a function of viewpoint• as a function of time• as a function of wavelength
7. 7. The 5D Plenoptic FunctionLet’s ignore color and time (i.e., these are attributes of rays)… P(q, f, px, py, pz)The plenoptic function is 5D:• 3D position• 2D directionRequire 5D to represent attributes across occlusions
8. 8. The 4D Light Field Consider a region free of occluding objects… P(q, f, px, py, pz) The plenoptic function (light field) is 4D • 2D position • 2D direction The space of all lines in a 3D space is 4D[Levoy and Hanrahan 1996; Gortler et al. 1996]
9. 9. Position-Angle Parameterization2D position2D direction s q
10. 10. Two-Plane Parameterization2D position2D position u s
11. 11. Alternative Parameterizations Left: Points on a plane or curved surface and directions leaving each point Center: Pairs of points on the surface of a sphere Right: Pair of points on two different (typically parallel) planes
12. 12. Image-Based Rendering [Levoy and Hanrahan 1996] [Gortler et al. 1996] [Carranza et al. 2003]
13. 13. Digital Image Refocusing Kodak 16-megapixel sensor 125μ square-sided microlenses[Ng 2005]
14. 14. 3D DisplaysParallax Panoramagram 3DTV with Integral Imaging MERL 3DTV [Kanolt 1918] [Okano et al. 1999] [Matusik and Pfister 2004]
15. 15. Multiple Sensors
16. 16. Static Camera Arrays Stanford Multi-Camera Array Distributed Light Field Camera 125 cameras using custom hardware 64 cameras with distributed rendering [Wilburn et al. 2002, Wilburn et al. 2005] [Yang et al. 2002]
17. 17. Temporal Multiplexing
18. 18. Controlled Camera or Object Motion Stanford Spherical Gantry Relighting with 4D Incident Light Fields [Levoy and Hanrahan 1996] [Masselus et al. 2003]
19. 19. Uncontrolled Camera or Object Motion Unstructured Lumigraph Rendering [Gortler et al. 1996; Buehler et al. 2001]
20. 20. Spatial Multiplexing
21. 21. Parallax Barriers (Pinhole Arrays) barriersensorSpatially-multiplexed light field capture using masks (i.e., barriers):• Cause severe attenuation  long exposures or lower SNR• Impose fixed trade-off between spatial and angular resolution (unless implemented with programmable masks, e.g. LCDs)[Ives 1903]
22. 22. Light Field Photograph (Sensor)
23. 23. Light Field Photograph (Decoded) looking to the rightlooking up Sample Image[The (New) Stanford Light Field Archive]
24. 24. Integral Imaging (“Fly’s Eye” Lenslets)lenslet fsensorSpatially-multiplexed light field capture using lenslets:• Impose fixed trade-off between spatial and angular resolution[Lippmann 1908]
25. 25. Modern, Digital ImplementationsDigital Light Field Photography• Hand-held plenoptic camera [Ng et al. 2005]• Heterodyne light field camera [Veeraraghavan et al. 2007]