Slide 1

Outline
technologies
large camera arrays
large projector arrays
camera–projector arrays
optical effects
synthetic aperture photography
synthetic aperture illumination
synthetic confocal imaging

Multi-camera systems
multi-camera vision systems
omni-directional vision
1D camera arrays
2D camera arrays

Stanford multi-camera array
640 × 480 pixels ×
30 fps × 128 cameras ÷ 18:1 MPEG = 512 Mbs
snapshot or video
synchronized timing
continuous streaming
cheap sensors & optics
flexible arrangement

Applications for the array
How are the cameras arranged?
tightly packed high-performance imaging
widely spaced light fields
intermediate spacing synthetic aperture photography

Cameras tightly packed:
high-performance imaging
high-resolution
by abutting the cameras’ fields of view
high speed
by staggering their triggering times
high dynamic range
mosaic of shutter speeds, apertures, density filters
high precision
averaging multiple images improves contrast
high depth of field
mosaic of differently focused lenses

Abutting fields of view
Q.  Can we align images this well?

Cameras tightly packed:
high-performance imaging
high-resolution
by abutting the cameras’ fields of view
high speed
by staggering their triggering times
high dynamic range
mosaic of shutter speeds, apertures, density filters
high precision
averaging multiple images improves contrast
high depth of field
mosaic of differently focused lenses

High-speed photography

A virtual high-speed video camera
[Wilburn, 2004 (submitted) ]
52 cameras, each 30 fps
packed as closely as possible
staggered firing, short exposure
result is 1560 fps camera
continuous streaming
no triggering needed

Example

A virtual high-speed video camera
[Wilburn, 2004 (submitted) ]
52 cameras, 30 fps, 640 × 480
packed as closely as possible
short exposure, staggered firing
result is 1536 fps camera
continuous streaming
no triggering needed
scalable to more cameras
limited by available photons
overlap exposure times?

Cameras tightly packed:
high-X imaging
high-resolution
by abutting the cameras’ fields of view
high speed
by staggering their triggering times
high dynamic range
mosaic of shutter speeds, apertures, density filters
high precision
averaging multiple images improves contrast
high depth of field
mosaic of differently focused lenses

High dynamic range  (HDR)
overcomes one of photography’s key limitations
negative film  =  250:1  (8 stops)
paper prints    =  50:1
[Debevec97]  =  250,000:1  (18 stops)
hot topic at recent SIGGRAPHs

Cameras tightly packed:
high-X imaging
high-resolution
by abutting the cameras’ fields of view
high speed
by staggering their triggering times
high dynamic range
mosaic of shutter speeds, apertures, density filters
high precision
averaging multiple images improves contrast
high depth of field
mosaic of differently focused lenses

Seeing through murky water
scattering decreases contrast
noise limits perception in low contrast images
averaging multiple images decreases noise

Seeing through murky water
scattering decreases contrast, but does not blur
noise limits perception in low contrast images
averaging multiple images decreases noise

Seeing through murky water

Cameras tightly packed:
high-X imaging
high-resolution
by abutting the cameras’ fields of view
high speed
by staggering their triggering times
high dynamic range
mosaic of shutter speeds, apertures, density filters
high precision
averaging multiple images improves contrast
high depth of field
mosaic of differently focused lenses

High depth-of-field
adjacent views use different focus settings
for each pixel, select sharpest view

Synthetic aperture photography

Synthetic aperture photography

Synthetic aperture photography

Synthetic aperture photography

Synthetic aperture photography

Synthetic aperture photography

Long-range
synthetic aperture photography

Synthetic pull-focus

Crowd scene

Crowd scene

Synthetic aperture photography
using an array of mirrors
11-megapixel camera
22 planar mirrors

Slide 32

Slide 33

Synthetic aperture illumation

 Synthetic aperture illumation
technologies
array of projectors
array of microprojectors
single projector  +  array of mirrors
applications
bright display
autostereoscopic display  [Matusik 2004]
confocal imaging  [this paper]

Confocal scanning microscopy

Confocal scanning microscopy

Confocal scanning microscopy

Confocal scanning microscopy

Slide 40

Synthetic confocal scanning

Synthetic confocal scanning

Synthetic confocal scanning
works with any number of projectors    2
discrimination degrades if     point to left of
no discrimination for    points to left of
slow!
poor light efficiency

Synthetic coded-aperture
confocal imaging
different from coded aperture imaging in astronomy
[Wilson, Confocal Microscopy by Aperture Correlation, 1996]

Synthetic coded-aperture
confocal imaging

Synthetic coded-aperture
confocal imaging

Synthetic coded-aperture
confocal imaging

Synthetic coded-aperture
confocal imaging

Synthetic coded-aperture
confocal imaging

Synthetic coded-aperture
confocal imaging

Synthetic coded-aperture
confocal imaging

Example pattern

Patterns with less aliasing

Implementation using an array of mirrors

Slide 55

Synthetic aperture confocal imaging

Selective illumination using object-aligned mattes

Confocal imaging in scattering media
small tank
too short for attenuation
lit by internal reflections

Experiments in a large water tank

Experiments in a large water tank
4-foot viewing distance to target
surfaces blackened to kill reflections
titanium dioxide in filtered water
transmissometer to measure turbidity

Experiments in a large water tank
stray light limits performance
one projector suffices if no occluders

Seeing through turbid water

Other patterns

Other patterns

Stripe-based illumination
if vehicle is moving, no sweeping is needed!
can triangulate from leading (or trailing) edge of stripe, getting range (depth) for free

Slide 66

Strawman conclusions on
imaging through a scattering medium
shaping the illumination lets you see 2-3x further, but requires scanning or sweeping
use a pattern that avoids illuminating the media along the line of sight
contrast degrades with increasing total illumination, regardless of pattern

Application to
underwater exploration

The team
staff
Mark Horowitz
Marc Levoy
Bennett Wilburn
students
Billy Chen
Vaibhav Vaish
Katherine Chou
Monica Goyal
Neel Joshi
Hsiao-Heng Kelin Lee
Georg Petschnigg
Guillaume Poncin
Michael Smulski
Augusto Roman
collaborators
Mark Bolas
Ian McDowall
Guillermo Sapiro
funding
Intel
Sony
Interval Research
NSF
DARPA

Relevant publications
(in reverse chronological order)
Spatiotemporal Sampling and Interpolation for Dense Camera Arrays
Bennett Wilburn, Neel Joshi, Katherine Chou, Marc Levoy, Mark Horowitz
ACM Transactions on Graphics (conditionally accepted)
Interactive Design of Multi-Perspective Images for Visualizing Urban Landscapes
Augusto Román, Gaurav Garg, Marc Levoy
Proc. IEEE Visualization 2004
Synthetic aperture confocal imaging
Marc Levoy, Billy Chen, Vaibhav Vaish, Mark Horowitz, Ian McDowall, Mark Bolas
Proc. SIGGRAPH 2004
High Speed Video Using a Dense Camera Array
Bennett Wilburn, Neel Joshi, Vaibhav Vaish, Marc Levoy, Mark Horowitz
Proc. CVPR 2004
High Speed Video Using a Dense Camera Array
Bennett Wilburn, Neel Joshi, Vaibhav Vaish, Marc Levoy, Mark Horowitz
Proc. CVPR 2004
The Light Field Video Camera
Bennett Wilburn, Michael Smulski, Hsiao-Heng Kelin Lee, and Mark Horowitz
Proc. Media Processors 2002, SPIE Electronic Imaging 2002

Slide 71