Polarimetric Scattering Analysis For Accurate Observation of

Stricken Man-made Targets Using A Rotated Coherency Matrix

Ryoichi Sato*, Yoshio Yamaguchi,and Hiroyoshi Yamada

Niigata University, Japan

IGARSS2010, July 25-30, 2010, Honolulu, Hawaii, USA

- June 15, 2008 Iwate-Miyagi Nairiku Earthquake, Japan, M7.2

IntroductionM7.0 class big earthquakes successively occurred in JAPAN not only in urban areas but also in severe mountainous areas

- March 20, 2005 West of Fukuoka Prefecture Earthquake, Japan, M7.0

- March 25, 2007 Noto Hanto Earthquake, Japan, M6.9

- July 16, 2008 Niigataken Chuetsu-oki Earthquake, Japan, M6.8

- October 23, 2004 Mid-Niigata Prefecture Earthquake, Japan, M6.8

Introduction

To escape damages of secondary disasters

Grasp the situation around the disaster area

Copyright©1998-2006 NTT DATA CORPOLATION Copyright©1998-2006 NTT DATA CORPOLATION

Difficulty of on-site inspections

Immediately after big earthquake…

*We express our sincere appreciations to Prof. Makino and NTT data for providing these high resolution photos.

Introduction

To escape damages of secondary disasters

Grasp the situation around the disaster area

Radar remote sensing based on POLSAR image analysis

ALOS/PALSAR

http://www.alos-restec.jp/aboutalos1.html

Space-borne POLSAR

Pi-SAR

Air-borne POLSAR

quad. POLSAR data acquisition

Introduction

10

10

000

2

1

800

075

0515

30

1

000

01

0

000

0

01*

2

2

*

j

jffffT cvds

PdPs Pv Pc

Scattering power decomposition [1]-[3]

[1] A. Freeman and S. L. Durden, ``A Three-component scattering model for polarimetric SAR data,`` IEEE Trans. Geosi. Remote Sensing, Vol.36, No. 3, pp. 963-973, May 1998.

[2] Y. Yamaguchi, T. Moriyama, M. Ishido and H. Yamada, ``Four-Component Scattering Model for Polarimetric SAR Image Decomposition,`` IEEE Trans. Geosi. Remote Sensing, Vol.43, No.8, pp.1699-1706, Aug. 2005.

[3] Y. Yajima, Y. Yamaguchi, R. Sato and H. Yamada, ``POLSAR image analysis of wetlands using a modified four-component scattering power decomposition,`` IEEE Trans. Geosi. Remote Sensing, Vol.46, No.6, pp.1667-1673, June 2008.

2/sin)( p

Introduction

Ps

Pd

Pv

illu

min

atio

n

SAPPORO

Urban area

Misclassification of man-made targets

Strong volume scattering

Targets are aligned obliquely to the illumination

Introduction

Strong Pd

Furthermore…

Before earthquake After earthquake

Weak Pd

Strong Ps

Strong Pv

Objective

Accuracy improvement of man-made target detection/extraction in POLSAR image analysis

Introduction of ``unitary rotation[4],[5]’’ of the coherency matrix

FDTD polarimetric scattering analysis for simplified man-made target model

To check the validity of the rotation,

[4] J.-S. Lee and D.L.Schuler and T. L. Ainsworth, ``Polarimetric SAR data Compensation for Terrain Azimuth Slope Variation,” IEEE Trans. Geosi. Remote Sensing, vol.38, no.5, pp.2153-2163, Sept. 2000.

[5] H. Kimura, K.P.Papathanassiou, and I. Hajnsek, ``Polarization orientation angle effects in urban areas on SAR data,” Proc. of IGARSS 2005, Seoul, South Korea, July 2005.

Derivation of ``rotation angle’’

10

10

000

2

1

800

075

0515

30

1

000

01

0

000

0

01*

2

2

*

j

jffffT cvds

PdPs Pv Pc

2/sin)( p

Scattering power decomposition (4-components model):

[1] A. Freeman and S. L. Durden, ``A Three-component scattering model for polarimetric SAR data,`` IEEE Trans. Geosi. Remote Sensing, Vol.36, No. 3, pp. 963-973, May 1998.

[2] Y. Yamaguchi, T. Moriyama, M. Ishido and H. Yamada, ``Four-Component Scattering Model for Polarimetric SAR Image Decomposition,`` IEEE Trans. Geosi. Remote Sensing, Vol.43, No.8, pp.1699-1706, Aug. 2005.

[3] Y. Yajima, Y. Yamaguchi, R. Sato and H. Yamada, ``POLSAR image analysis of wetlands using a modified four-component scattering power decomposition,`` IEEE Trans. Geosi. Remote Sensing, Vol.46, No.6, pp.1667-1673, June 2008.

x

xx

xx

T reflection

00

0

0

Reflection symmetry

u

//u

0~~ **HVVVVHHH SSSS

Derivation of ``rotation angle’’Scattering power decomposition (4-components model):

10

10

000

2

1

800

075

0515

30

1

000

01

0

000

0

01*

2

2

*

j

jffffT cvds

PdPs Pv Pc

Measured coherency matrix

2/sin)( p

xx

xx

x

T rotation

0

0

00

Rotation symmetry

Derivation of ``rotation angle’’Scattering power decomposition (4-components model):

10

10

000

2

1

800

075

0515

30

1

000

01

0

000

0

01*

2

2

*

j

jffffT cvds

PdPs Pv Pc

Measured coherency matrix

2/sin)( pu

//u

Roll invariant

xx

xx

x

T rotation

0

0

00

Rotation symmetry

x

xx

xx

T reflection

00

0

0

Reflection symmetry

Derivation of ``rotation angle’’Scattering power decomposition (4-components model):

10

10

000

2

1

800

075

0515

30

1

000

01

0

000

0

01*

2

2

*

j

jffffT cvds

PdPs Pv Pc

Measured coherency matrix

2/sin)( p

10

10

000

2

1

800

075

0515

30

1

000

01

0

000

0

01*

2

2

*

j

jffffT cvds

2**

*2*

**2

4)(2)(2

)(2)()(

)(2))((

2

1

HVVVHHHVVVHHHV

VVHHHVVVHHVVHHVVHH

VVHHHVVVHHVVHHVVHH

SSSSSSS

SSSSSSSSS

SSSSSSSSS

T

Derivation of ``rotation angle’’Scattering power decomposition (4-components model):

PdPs Pv Pc

Measured coherency matrix2/sin)( p

Derivation of ``rotation angle’’

2**

*2*

**2

4)(2)(2

)(2)()(

)(2))((

2

1

HVVVHHHVVVHHHV

VVHHHVVVHHVVHHVVHH

VVHHHVVVHHVVHHVVHH

SSSSSSS

SSSSSSSSS

SSSSSSSSS

T

Measured coherency matrix

Expanded coherency matrix

000

0

012

*

000

01

0*

2

800

075

0515

30

1

800

075

0515

30

1

100

010

002

4

1

10

10

000

2

1

j

j

PdPs Pv Pc

Inconsistency)(2 *13 VVHHHV SSST *

31 )(2 VVHHHV SSST 0

Derivation of ``rotation angle’’``Rotation’’ of the measured coherency matrix

2cos2sin0

2sin2cos0

001

2cos2sin0

2sin2cos0

001

TT

02cos2sin 131213 TTT

Condition for determining the rotation angle

12

131tanˆ2T

T

So we obtain the rotation angle as

Complex angle

Derivation of ``rotation angle’’

after carrying out the averaging processing,

12

13

12

13 ImReT

T

T

T

- For obliquely oriented man-made target area

We approximately choose the rotation angle as

ˆRe~

12

131tanˆ2T

T

'13T becomes small, but not zero.

it is often observed

Modified algorithm with Re{T13} rotation

2cos2sin0

2sin2cos0

001

2cos2sin0

2sin2cos0

001

TT

02cos2sin 131213 TTT

1. Determination of the rotation angle

2. Obtain the rotated coherency matrix using T

3. Scattering power decomposition for the rotated matrix T

Pre-processing

Modified algorithm with T33 rotation

2cos2sin0

2sin2cos0

001

2cos2sin0

2sin2cos0

001

TT

0/)(33 dTd Minimize

2. Obtain the rotated coherency matrix using T

3. Scattering power decomposition for the rotated matrix T

Pre-processing

'33T

1. Determination of the rotation angle

In the previous presentation by Prof. Yamaguchi (in EUSAR2010 etc. )

POLSAR data description

Mode: Quad.Pol. HH+HV+VH+VV

Pi-SAR

Quad. polarimetric data take function

Pi-SAR**

Resolution 3m by 3m

Total pixel number (entire region)

6,000 by 4,000

Averaging size (pixels) 5 by 5

Incident angle [deg.]

L-band 1.27GHz (l=0.236m)

**Acquired by NiCT, JAXA, Japan

Date

11/04/2004 Yamakoshi

27.2-53.3 deg.(Near - Far)

42.9 deg.(Center)

Result

illu

min

atio

n

w/o rotation

Ps

Pd

Pv

Yamakoshi (Niigata, Japan)

11/04/2004

area A

area B

Result for area A

Ps

Pd

Pv

illu

min

atio

n

w/o rotation T33 rotation

Re{T13} rotationYamakoshi (Niigata, Japan)

11/04/2004

illu

min

atio

nil

lum

inat

ion

Result for area B il

lum

inat

ion

w/o rotation T33 rotation

Ps

Pd

Pv

Yamakoshi (Niigata, Japan) Re{T13} rotation

11/04/2004

illu

min

atio

nil

lum

inat

ion

Polarimetric FDTD analysisPolarimetric scattering analysis for a quad man-made

target model by using the FDTD method

f

q

Plane wave incidence

f=1.2GHz (L-band)

H-pol

V-pol

x

y

z

f= 5 to 35 [deg.]

Polarimetric FDTD analysisParameters in the FDTD analysis

f

q

=45 [deg.]

f=1.2GHz (L-band)

H

W

W=L=1.2m (4.8l)

H=1.6m (6.4l)

Permittivity & conductivity

main part: e r=4 s=0.0070

base part: e r=7 s=0.0141

(er=4-j0.2 at 1.2GHz )

(er=7-j0.1 at 1.2GHz )

H-pol

V-pol

Analytical region

Cubic cell size DTime step Dt

Incident pulse

Absorbing boundary condition

700 X 700 X 350 cells

0.01m

1.925 X 10-11 s

Lowpass Gaussian pulse

PML (8 layer)

D

D=0.3m (1.2l)

R

R=3.0m (12.0l)L

x

y

z

f:variable

Polarimetric FDTD analysis

Plain view

To evaluate statistical polarimetric scattering feature as actual POLSAR image analysis,

Statistical evaluation

y

x

Ensemble average processing is carried out for 10 degs. squint anguler range (Average of 10 angles).

15-25deg.5-15deg.Squint angle

y

x

y

x25-35deg.

y

x

5-15deg.

Polarimetric FDTD analysis

Pt=Pd+Ps+Pv+Pc

=45o

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00w/o rotation

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00Re{T13} rotation

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00 T33 rotation

y

x

15-25deg.

Polarimetric FDTD analysis

Pt=Pd+Ps+Pv+Pc

=45o

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00w/o rotation

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00Re{T13} rotation

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00 T33 rotation

y

x

25-35deg.

Polarimetric FDTD analysis

Pt=Pd+Ps+Pv+Pc

=45o

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00w/o rotation

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00Re{T13} rotation

Pd/Pt Ps/Pt Pv/Pt Pc/Pt0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00 T33 rotation

Polarimetric FDTD analysisSummary of the rotation effect

5-15

15-25

25-35

Re{T13} rotation T33 rotationSquint angle

(No need) (No need)

Conclusion

Re{T13} and T33 rotations are both valid.

Accuracy improvement of man-made target detection/extraction in POLSAR image analysis

``Unitary rotation’’ of the coherency matrix

From the results of POLSAR image analysis

Confirmation of the validity of ``rotation’’

The ``rotation’’ is efficient at least up to 30o in squint angular range

FDTD polarimetric scattering analysis for simplified man-made targets

Outlook

Determination of more appropriate/rigorous rotation angle

More accurate man-made targets detection/extraction

FDTD polarimetric scattering analysis for man-

made target model on slope/rough ground

in stricken area i.e.

in inclined and/or rough surface area

Acknowledgments- The authors express their sincere appreciations to JAXA and NiCT, Japan, for providing valuable ALOS/PALSAR and Pi-SAR image data sets.

- This research was partially supported by A Scientific Research Grant-In-Aid (19510183) from JSPS, Japan, and Telecom Engineering Center (TELEC).

Thank you!