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Light Field Rendering

Light Field Rendering. Shijin Kong Lijie Heng. Overview. Purpose Algorithm 1. representation of light field-4D (u, v, s, t) 2. creation 3. compression 4. display Discussion Applications . Purpose. To generate a new view from an arbitrary position Previous methods

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Light Field Rendering

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  1. Light Field Rendering Shijin Kong Lijie Heng

  2. Overview • Purpose • Algorithm 1. representation of light field-4D (u, v, s, t) 2. creation 3. compression 4. display • Discussion • Applications

  3. Purpose • To generate a new view from an arbitrary position • Previous methods Environment maps - depth information Interpolating - correspondence points

  4. Purpose-Cont. • Limit: “fill in the gaps”, incorrect correspondences • To avoid these problems, a new method was proposed in this paper by using light field

  5. What is Light Field • In the real 3D world, how to represent a ray? Using 5D Plenoptic Function

  6. 4D Representation • In free space (no occluders), oriented lines could be represented in 4D

  7. Representation of Light Field

  8. Creation of Light Field • Rendered Images

  9. Creation of Light Fields • Aliasing Low-pass filter

  10. Display Show video

  11. Discussion • Advantages 1. easy, robust 2. fast to create new views -sampling • Limitations Large amount of data Building acquisition device Fixed focal surface

  12. Discussion • Limitations Large amount of data Building acquisition device Fixed focal surface

  13. Compression • VQ • Lempel-Zic Coding

  14. Compression -Cont.

  15. Discussion • Limitations Large amount of data Building acquisition device Fixed focal surface

  16. Acquisition-Option1 • Using a single camera -hard to manipulate -need refocus -aliasing/blurriness

  17. Signal Camera

  18. Acquisition-Option2 • Using an array of cameras -fixed -inflexible

  19. Camera Arrays

  20. Acquisition-Option3 • Using an microlens array to replace the camera array -easy to use -reduce aliasing

  21. Hand-held Plenoptic Camera

  22. Hand-held Plenoptic Camera- Cont.

  23. More on Plenoptic Camera • Higher image resolution, increased sharpness of the refocused photographs. • Shorter exposures and lower image noise

  24. Discussion • Limitations Large amount of data Building acquisition device Fixed focal surface

  25. Dynamic Reparameterized Light Fields • Focal Surface is fixed when create light fields • What if recover pixels that are not on the focal surface • Reparameterize to required focal surface

  26. Dynamic Reparameterized Light Fields • Move to desired new focal surface • Create a new 4D space with new focal surface • Recove ray with Reparameterization • (u, v, s, t) => (u, v, f, g)F

  27. Dynamic Reparameterized Light Fields • Recover ray r • Resample from ray (s’, t’, f, g) and (s’’, t’’, f, g) • Interpolation, reconstruction with filter, … , etc

  28. Dynamic Reparameterized Light Fields

  29. Dynamic Reparameterized Light Fields • Change the shape of focal surface • Gives focus on 3D object rather than planes

  30. Dynamic Reparameterized Light Fields

  31. Dynamic Reparameterized Light Fields

  32. Variable Apertures • Also can generate variable aperture • Aperture • Control amount of light • Control depth of fields • Aperture Filter: • Control how many cameras are used to resample a required ray • Larger apertures produce images with narrow range of focus

  33. Aperture Filters

  34. Variable Apertures

  35. Variable Apertures

  36. Application of Light Fields • Multipersepective panorama • Lens simulation

  37. Applications of Light Field • Multipersepective panorama

  38. Applications of Light Field • Lens simulation • Simulate lens with large aperture

  39. Future of Light Field • Need better ways to capture larger collection of viewpoints • Reconstruct 3D shape with vision algorithms • More images captured allow peeking arround occlusions

  40. Thank you! Questions?

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