1 camera polarizer analyzer protractor lens Yoav Y Schechner EE Technion Israel S elfcalibration in other imaging problems Y Schechner selfcalibrating polarimetry ID: 788408
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Slide1
Self-Calibrating Imaging Polarimetry
1
camera
polarizer (analyzer)
protractor
lens
Yoav Y.
Schechner
EE, Technion , Israel
Slide2Self-calibration
in other imaging problems
Y. Schechner,
self-calibrating polarimetry
2
Slide3Self-calibration of radiometric properties
spatial non-uniformity
pixel
electronic readout
light intensity
A. Litvinov & Y. Schechner,
radiometric nonidealities
Spatial non-uniformity Time-varying gain
Response
nonlinearity
3
Debevec
; Malik (98)
Mitsunaga
;
Nayar
(99)
Kim;
Pollefeys
(04)
Schechner
;
Nayar
(01)
Slide4Structure from Motion (
SfM
)
4
Unknown
Unknown
Schechner
Slide5Polarization
Y
. Schechner, self-calibrating polarimetry
5
Slide6Tedious,
inaccurate control
N. Karpel
& Y. Schechner, underwater imaging
protractor
polarizer
6
Slide7polarizer
180
o
3 general measurements
suffice,
a
t
known orientations
Polarization
vector
determination
camera
Y
.
Schechner
,
self-calibrating polarimetry
7
Slide8polarizer
180
o
What about
unknown
orientations
?
Polarization
vector
determination
camera
Y
.
Schechner
,
self-calibrating polarimetry
8
Slide99
Self-calibration would allow
Easy polarimetry-based methods, by lay person
(SLR? Smartphone?)Scientific exploration by the lay person
Less hassle for experimentalists (lab and field)Increase tolerance in scientific-grade specsBiological understanding
Y
.
Schechner
,
self-calibrating polarimetry
Slide1010
Y
.
Schechner
, self-calibrating polarimetry
camera
11
Y
.
Schechner
,
self-calibrating polarimetry
camera
polarizer
12
Y
.
Schechner
,
self-calibrating polarimetry
camera
polarizer
13
Y
.
Schechner
,
self-calibrating polarimetry
Slide1414
2
=
Y
.
Schechner
,
self-calibrating polarimetry
Slide1515
2
=
Y
.
Schechner
,
self-calibrating polarimetry
Slide1616
2
P
=
Y
.
Schechner
,
self-calibrating polarimetry
Slide1717
2
P
=
Y
.
Schechner
,
self-calibrating polarimetry
Slide1818
2
P
=
Y
.
Schechner
,
self-calibrating polarimetry
Slide1919
2
P
D
=
Y
.
Schechner
,
self-calibrating polarimetry
Slide2020
2
P
O
D
=
Y
.
Schechner
,
self-calibrating polarimetry
Slide2121
2
P
O
D
=
Y
.
Schechner
,
self-calibrating polarimetry
Slide22Y
.
Schechner
, self-calibrating polarimetry
22
D
=
P
O
At least 3 object points and 4 images
At least 2 object points and 5 images
Slide2323
D
=
P
O
arg
min ||
D
-
P
O
||
P
Y
.
Schechner
,
self-calibrating polarimetry
Slide2424
arg
min ||
D
-
P
O
||
P
O
,
Y
.
Schechner
,
self-calibrating polarimetry
Slide2525
Given
P
(standard polarimetry)
O
=
arg
min ||
D
-
P
O
||
O
Y
.
Schechner
,
self-calibrating polarimetry
Slide2626
P
arg
min ||
D
-
P
O
||
O
,
Y
.
Schechner
,
self-calibrating polarimetry
Slide2727
arg
min ||
D
-
P
O
||
~
P
T
~
P
T
Given
O
Y
.
Schechner
,
self-calibrating polarimetry
Slide2828
arg
min ||
-
||
~
P
T
~
P
Given
O
T
~
O
T
~
D
r
Result:
T
~
P
Y
.
Schechner
,
self-calibrating polarimetry
Slide29Y
. Schechner
, self-calibrating polarimetry
29
~
P
T
Result:
T
~
P
30
Result:
T
~
P
Normalize rows
Y
.
Schechner
,
self-calibrating polarimetry
Slide31Y
.
Schechner
, self-calibrating polarimetry
31
Roughly guessed
O
=
arg
min ||
D
-
P
O
||
O
=
arg
min ||
-
||
~
P
T
~
P
T
~
O
T
~
D
r
T
~
P
Angle estimates
Slide32camera
lens
polarizer (analyzer)
rotating mountTripod-head
camera
polarizer (analyzer)
rotating
mount
protractor
lens
32
Y
.
Schechner
,
self-calibrating polarimetry
Slide3333
Y
.
Schechner,
self-calibrating polarimetry
Slide3434
45
135
0
90
170
20
110
50
80
140
200
hundred iterations
true
first guess
Y
.
Schechner
,
self-calibrating polarimetry
Slide3535
30
60
90
120
150
0
180
30
60
90
120
0.2
0.2
0.4
0.4
0.6
0.6
0.8
0.8
0
Y
.
Schechner
,
self-calibrating polarimetry
Slide3636
Y
.
Schechner,
self-calibrating polarimetry
Slide3745
60
90
135
180
0
150
30
90
120
45
135
180
0
90
20
110
50
80
140
200
Y
.
Schechner
,
self-calibrating polarimetry
37
hundred iterations
true
first guess
38
30
60
90
120
150
0
180
30
60
90
120
0.2
0.2
0.4
0.4
0.6
0.6
0.8
0.8
0
Y
.
Schechner
,
self-calibrating polarimetry
Slide39||
D
-
P
O ||
2
||
D
-
P
O
||
2
e
=
true
true
39
iteration
10
100
1
10
100
1,000
1
Schechner
Slide4040
Code available online:
webee.technion.ac.il
/~yoav/research/polar-self-calib
Y. Schechner
, self-calibrating polarimetry
Polarimetric
imaging has a
self-calibration capacity !!