1. IGARSS 2011
Classification of Typhoon-Destroyed Forests Based on Tree Height Change Detection Using InSAR Technology
Haipeng Wang 1, Kazuo Ouchi 2, and Ya-Qiu Jin1
1. Key Laboratory of Wave Scattering and Remote Sensing
Fudan University, P.R. China.
2. Department of Computer Science
National Defense Academy of Japan, Japan.

2. Purpose of This Study
The final goal is to establish methodology to estimate the parameters of
forests from high-resolution SAR data.
This first study we carried out is to quantify the relation between
high-resolution polarimetric SAR data and tree biomass of forests.
This second one is to extract the information of typhoon-damaged forests.
The methodology is to utilize the texture information, polarimetric analysis
and interferometric technique.
The test site is the Tomakomai forests in Hokkaido, Japan.
The SAR data were collected using the airborne Pi-SAR.
Read it

3. Tomakomai National Forests
Shikotsu Lake
Larch
Todo Fir
Red Pine
Spruce

4. Pi-SAR
Pi-SAR (Polarimetric interferometric - SAR) is an airborne SAR developed jointly
by NICT (National Institute of Information and Communications Technology) and
JAXA (Japan Aerospace Exploration Agency).
It is equipped with two X-band antennas (frequency 9.55 GHz, wavelength 3.14 cm)
and a L-band antenna operating at frequency 1.27 GHz (wavelength 23.6 cm).
The nominal resolution is 1.5 x 1.5 m at X-band, and 3 x 3 m at L-band for 4-look
azimuth multilooking.
L-band antenna
X-band main antenna
X-band
sub-antenna

5. Pi-SAR Data L-band colour composite polarimetric Pi-SAR image
Shikotsu Lake
study area
Tomakomai City
range
Tarumae Mt.
azimuth
JAXA/NICT
Data acquired:7th, November, 2002
range
azimuth
study area
Data acquired:3rd, November, 2004

6. Ground-Truth Biomass Data Collection
Field measurements were made in 2002, 2003, 2005, and in 2006.
Tree species, height, DBH (Diameter at Breast Height), basal area, soil moisture were measured within a 20 x 20 m sample area in each stands, and converted to above-ground biomass using the conversion formula provided by Project department (Stand volume table -East Japan-, Japan Forestry Investigation Committee. Tokyo: Forestry Agency, Oct. 1998)

7. Typhoon Songda Typhoon Songda (Japanese No.18)
Duration:August 28 – September 8
Typhoon Songda killed 20 people and injured 700 others in Japan. In addition, 15 crew members of a vessel were reported missing.
Damages from the storm amounted to $7.17 billion (2004 USD)
Time arrived at Tomakomai: September 7th, 2004

8. Fallen Trees After Typhoon

9. Ground-Truth Data

10. Amplitude Analysis Whole image Test sites Image No. HH HV VV L6407
L8104
L6407-L8104
0.4682
Test sites
Site No.
HH subtraction
HV subtraction
VV subtraction
196
0.8403
0.6001
197
0.9535
0.5802
198
0.8714
0.3279
217&218
0.8619
0.4444
243
0.8975
0.4549
245
0.9827
0.3009
267
0.9856
0.4899
271
0.8962
0.4392
300
0.8269
0.4759
302
0.7889
0.3169
268
0.6641
0.0218
303
0.5009

11. Amplitude Analysis Results
Accuracy:64.1%

12. Scattering Mechanisms From Forests
X/C-bands
multiple reflection
between ground and
tree trunks/branches
L/P-bands
scattering from
crown parts
multiple/volume
scattering from branches
surface scattering
from ground

13. Three-Component Decomposition Analysis
Double
Volume
Surface
L6407
L8104
L6407-L8104
Site No.
Double subtraction
Volume subtraction
Surface subtraction
196
1.1277
197
1.0917
198
0.4771
217&218
0.7719
243
0.7808
245
0.4519
267
0.9402
271
0.8799
300
0.8673
302
0.4366
268
303
A. Freeman and S. L. Durden, “A three-component scattering model for polarimetric SAR data,” IEEE Trans. Geosci. Remote Sens., vol. 36, no. 3, pp. 936–973, May 1998.

14. Scattering Mechanism Analysis Result
Accuracy:77.7%

15. Pi-SAR Pi-SAR on Gulf Stream II X-band and L-band radomes
X-band main antenna
X-band
sub-antenna
L-band antenna
Pi-SAR on Gulf Stream II
X-band and L-band radomes
Pi-SAR was developed jointly by NICT (National Information & Communication Agency) and JAXA (Japan Aerospace Exploration Agency), consisting of two X-band radomes
and a single L-band radome. the X-band main radome consists of two antennas. The first antenna is used for H-polarization and the second antenna for V-polarization.
The sub-radome was not used for the Naruto data collection. The two antennas inside the first radome is separated by d=20cm, and therefore polarimetric interferometric
analysis can be made. It is not, however, full Pol-InSAR, because we only have HH1, HV1, and VV2 data.
Partial Pol-InSAR by X-band main radome
(Sub-antenna data not acquired this time)
Two antennas within X-band main radome

16. Pi-SAR Data for Interferometric Analysis
X-band VM Pi-SAR image
Data acquired:3rd, August, 2004
Data acquired:3rd, November, 2004

17. Complex Interferogram
Complex Degree of Coherence
M, N —— Moving window size
S —— Data

18. Phase Image

19. Removal of Orbital Fringes
X8104
X7904
Courtesy of Dr. Moriyama

20. Phase Unwrapping(X7904)

21. Phase Unwrapping(X8104)

22. Height Change

23. Conclusions and Future Work
Research was carried out to extract information of typhoo-damaged forests.
The accuracies of 64.1% and 77.7% were obtained for amplitude and decomposition data respectively.
InSAR processing resutls show it’s potential, but there is no quantitative results yet.
Phase unwrapping: other approaches rather than the branch cut.
Difficult to see the difference of typhoon-damaged information from the coherence data before and after the typhoon. Next step is to exam the coherence before and after the typhoon
Fusion of optical data and SAR data: QuickBird, IKONOS, Geoeye multispectrum optical data, Pi-SAR I&II data.