siggraph 2012 computational plenoptic imaging course - 4 light fields
DESCRIPTION
SIGGRAPH 2012 Computational Plenoptic Imaging Course - 4 Light FieldsTRANSCRIPT
Light Field Acquisition
Douglas Lanman
NVIDIA Research
Introduction to Light Fields
The 5D Plenoptic Function
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)
P( , , q f l, t)
The 5D Plenoptic Function
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)
P(q, f, l, t)
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
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
The 5D Plenoptic Function
Let’s ignore color and time (i.e., these are attributes of rays)…
The plenoptic function is 5D:• 3D position• 2D direction
Require 5D to represent attributes across occlusions
P( , , q f px, py, pz)
The 4D Light Field
Consider a region free of occluding objects…
The plenoptic function (light field) is 4D• 2D position• 2D direction
The space of all lines in a 3D space is 4D
P( , , q f px, py, pz)
[Levoy and Hanrahan 1996; Gortler et al. 1996]
Position-Angle Parameterization
2D position
2D direction
sq
Two-Plane Parameterization
2D position
2D position
su
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
Image-Based Rendering
[Levoy and Hanrahan 1996] [Gortler et al. 1996]
[Carranza et al. 2003]
Digital Image Refocusing
[Ng 2005]
Kodak 16-megapixel sensor
125μ square-sided microlenses
3D Displays
Parallax Panoramagram[Kanolt 1918]
3DTV with Integral Imaging[Okano et al. 1999]
MERL 3DTV[Matusik and Pfister 2004]
Multiple Sensors
Static Camera Arrays
Stanford Multi-Camera Array 125 cameras using custom hardware
[Wilburn et al. 2002, Wilburn et al. 2005]
Distributed Light Field Camera64 cameras with distributed rendering[Yang et al. 2002]
Temporal Multiplexing
Controlled Camera or Object Motion
Stanford Spherical Gantry[Levoy and Hanrahan 1996]
Relighting with 4D Incident Light Fields[Masselus et al. 2003]
Uncontrolled Camera or Object Motion
Unstructured Lumigraph Rendering[Gortler et al. 1996; Buehler et al. 2001]
Spatial Multiplexing
Parallax Barriers (Pinhole Arrays)
[Ives 1903]
sensor
barrier
Spatially-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)
Light Field Photograph (Sensor)
Light Field Photograph (Decoded)
[The (New) Stanford Light Field Archive]
loo
kin
g u
p
looking to the right
Sample Image
Integral Imaging (“Fly’s Eye” Lenslets)
[Lippmann 1908]
sensor
lenslet
f
Spatially-multiplexed light field capture using lenslets:• Impose fixed trade-off between spatial and angular resolution
Modern, Digital Implementations
Digital Light Field Photography• Hand-held plenoptic camera [Ng et al. 2005]• Heterodyne light field camera [Veeraraghavan et al. 2007]