Computational Photography

Light Fields

by dr. Francho Melendez

today's schedule

  • Recap
  • Light Fields
  • Light Field Capture
  • Light Field Cameras
  • Applications

recap

computational photography

  • plenoptic imaging

  • coded photography

  • computational displays

  • capturing light transport

plenoptic imaging (epsilon photography)

coded photography

  • Coded Illumination
  • Coded Exposure
  • Coded Apertures

coded illumination

several illumination coding strategies

temporal coding

directional coding

spatial coding

assisted stereo

coded camera

  • focus blur
  • motion blur

image Formation

Deblurring is a deconvolution

aperture, PSF, and motion

  • focus blur: Depth-dependent PSF
  • motion blur:depends on object
  • Circular apperture is not (well) invertible
  • Long exposures: not (well) invertible

focal sweep

coded apertures

coded apertures

coded apertures

coded exposures

coded exposures

parabolic sweep

parabolic curve:shear invariant

cameras and information preservation

coded rolling shutter

light field: definition

what is a light field?

5D plenoptic function

$L = L(x,y,z, \theta, \phi, \lambda, t)$

cameras capture irradiance

cameras capture irradiance

LF capture radiance

4D Light Field

Radiance along a ray remains constant if there are no blockers

Restricted to the convex-hull (no concave objects)

Parametrization

Some alternative parameterizations of the 4D light field, which represents the flow of light through an empty region of three-dimensional space. Left: points on a plane or curved surface and directions leaving each point. Center: pairs of points on the surface of a sphere. Right: pairs of points on two planes in general (meaning any) position.

2 Plane: Parametrization

Line parameterized by intersection with 2 planes

Visualization

integral imaging

integral imaging

integral imaging

Demo

press me

light fields

light fields

light fields

light fields

light fields

light fields

light fields

Visualization

capturing light fields

taxonomi

sequential

sequential

sequential

camera arrays

camera arrays

camera arrays

camera arrays

picam

spatial multiplexing

spatial multiplexing

spatial multiplexing

old idea

old idea

old idea

resolution tradeoff

resolution tradeoff

resolution tradeoff

data is very redundant, compressive sensing (next week)

panoramic LF and VR

panoramic LF and VR

panoramic LF and VR

plenoptic camera refocus

conventional photograph

light field photography

spatial multiplexing

structure

LF in a single exposure

LF in a single exposure

LF inside the camera body

Reconstructing normal image

Just integrate all the pixels in the aperture

digitally stop-down

change viewpoint

digital refocus

  • we have all the light rays
  • we can generate any virtual view

digital refocus

digital refocus

digital refocus

digital refocus

digital refocus

digital refocus

refocus

refocus

refocus

refocus

light field slice

also called Epipolar Image

epipolar slices

light field slice

also called Epipolar Image

light field slice

also called Epipolar Image

other applications

applications

applications

applications

applications

applications

applications

Otoy on Light fields

lab 7

  • Ligth field slice
  • Light Field Refocus
  • Simple depth estimation

Ligth field slice

Light Field Refocus

Simple depth estimation

http://franchomelendez.com/Uwr/teaching/COMPHO/_LECTURES/L9/light_fiedls.html

http://franchomelendez.com/Uwr/teaching/COMPHO/Labs/Lab8.zip


franchomelendez@cs.uni.wroc.pl

credits and references and aditional readings

These slides have been prepared with materials, slides, and discussions from the following.

  • Gordon Wetzstein
  • Fredo Durand