Polarimetric Calibration Using Distributed Odd-bounce Targets Jiong CHEN 1, 3* Motoyuki SATO 2 Jian...
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Transcript of Polarimetric Calibration Using Distributed Odd-bounce Targets Jiong CHEN 1, 3* Motoyuki SATO 2 Jian...
Polarimetric Calibration Using Distributed Odd-bounce TargetsPolarimetric Calibration Using
Distributed Odd-bounce Targets
Jiong CHEN 1, 3* Motoyuki SATO 2 Jian YANG 3
1. Graduate School of Environmental Studies, Tohoku University, Japan2. Center for Northeast Asian Studies, Tohoku University, Japan
3. Department of Electronic Engineering, Tsinghua University, China*E-mail: [email protected]
07/2011
HH HV
VH VV
S S
S S
HH HV
VH VV
Z Z
Z Z
After calibration
Retrieval of soil moisture
0
210 3
0
21 expHH
VV
ks
0
000.23 1 expVH
VV
ks
Estimation of biomass
Classification of terrainMonitoring of flood
Introduction
ALOS/PALSARY. Oh 1992 H. Yamada, et.al. 2001
2/13
Polarimetric Calibration
• Polarimetric SAR Model for Calibration
• Basic Assumptions
• Conventional Methods
41
3 22 1
11HH HV HH HV HH HV
VH VV VH VV VH VV
Z Z S S N N
Z Z S S F N NF
1. Reciprocity2.Statistical symmetryon distributed targets
3. Known Calibrators
HV VHS S * * 0HH VH VV VHS S S S 1 0
0 1TriS
Van Zyl Quegan Kimura
Assumption 1,2,3 Assumption 1,2 Assumption 1, Slight 2
3/13
Motivations
• The deployment of trihedral is inconvenient
– For low frequency system, the size should be relatively large
– To implement calibration ubiquitously
• The assumption is not always valid
– Only valid for statistically symmetric distributed targets
– Small value will cause large bias in the calibration results
* * 0HH VH VV VHS S S S
Develop a calibration method without the trihedral or the assumption * * 0HH VH VV VHS S S S
4/13
Basic Scheme and Assumptions
Conventional method : TrihedralConventional method : Trihedral
Proposed method : Use the statistic information of odd-
bounce targets
Proposed method : Use the statistic information of odd-
bounce targets
Robust estimator using odd-bounce targets
Robust estimator using odd-bounce targets
Assume cross-talk to be smallAssume cross-talk to be small
Advantage : 1. Standard trihedral calibrator is not needed 2. The assumption is not needed* * 0HH VH VV VHS S S S
Removal of non-reciprocal effect
Estimation of channel
imbalance
Estimation of cross-talk
Channel imbalance ratio
Channel imbalance product
5/13
Decomposition of Distortion Matrix
•
Channel ImbalanceChannel
ImbalanceNon-reciprocal
effectNon-reciprocal
effect Cross-talkCross-talk
1
1 2
2 1
1 2 1 1 1 1
1 0 1 'cos sin
0 ' ' 1sin cos
cos 'sin sin 'cos
' 'cos 'sin ' 'sin 'cos
R R RR I CF
F F F F
2
1 2
2 2 2 2
1 2 1 2
1 ' 1 0cos sin
' 1 0 'sin cos
cos 'sin ' 'cos 'sin
sin 'cos ' 'sin 'cos
T T TT C IF
F F
F F
6/13
Selection of Odd-bounce Targets
Statistical information of odd-bounce targets Trihedral
7/13
Typical odd-bounce targets
Statistical propertyAmplitude Phase
Flight direction
Optical image, captured from Google Earth
Removal of Channel Imbalance
•
Estimation of channel imbalance
Uncalibrated data
Removal of channel imbalance
Channel balanced data
Robust estimator for non-reciprocal effect
Non-reciporcaldistortion matrix
1 1
1 2
2 1
'
1 ' 1 'cos sin cos sin
' 1 ' 1sin cos sin cos
R T R R T T
HH HV
VH VV
Z I ZI C SC
S S
S S
8/13
Robust Estimator of Non-reciprocal Effect
• Odd-bounce targets : Good for the estimation of
• Distribution of on odd-bounce targets : Laplace
9/13
Similarity Parameters
2 2
1 2 1 2 1 22 2, /Hr S S k k k k
1, exp
2
xf x b
b b
1
ˆ arg minN
ii
x
The robust estimate
Fitting ResultLaplace distribution with
different parameters
Estimation of Cross-talk
•
10/13
1 2 4 3 1 2 1 2VH HV HH VVF Z F Z FF Z Z
4 1 21
3 2 3 42 1
11HH HH HH HV
VH VV VH VV
Z Z S S N N
Z Z S S F N NF
On Odd-bounce targets
2 1 2 1 1 2 1 2' ' ' '
VH HV HH VVF Z F Z FF Z Z
cos 1 sin Assuming
Assuming 1 2' '
Estimated Distortion Matrix
1 1
1 2 1 1 2 1
1 sin ' 1
' ' 'sin 'R
F F F F
42 2 2
3 21 2
11 ' ' 'sin
sin ' '
F FT
FF
Discussion on Results
• Calibration result
11/13
1.0000 0.0253 0.0038'
0.0180 0.0029 0.7145 0.0081
jR
j j
1.0000 0.0320 0.0068'
0.0320 0.0038 0.9638 0.3269
jT
j j
1.0000 0.0063 0.0071
0.0063 0.0080 0.7217 0.0237
jR
j j
1.0000 0.0024 0.0129
0.0115 0.0062 0.9572 0.3830
jT
j j
New distortion matrices
JAXA Standard distortion matrices
Co-polarized signature on trihedral
Uncalibrated JAXA standard calibrated result
New calibrated result Theoretical result
•
Removal of Faraday Rotation
Sendai 090604 Sendai 070414
Alaska 07072912/13
• A practical calibration scheme based on distributed odd-bounce targets is proposed
– The distortion matrix is decomposed firstly
– The statistical information of odd-bounce targets is used as alternative to trihedral
– A robust estimator based on odd-bounce targets is derived to estimate the non-reciprocal effect
– It can be used as a rough calibration method without the special deployment of trihedral calibrators, nor the un-correlation consumption
Conclusion
13/13