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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.
• 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.
Purpose of This Study
Tomakomai National Forests
Shikotsu Lake
Larch Todo Fir Red Pine Spruce
Pi-SAR
Pi-SAR (Polarimetric interferometric - SAR) is an airborne SAR developed jointlyby 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-lookazimuth multilooking.
L-band antenna
X-band main antenna
X-band sub-antenna
Pi-SAR Data
JAXA/NICT
L-band colour composite polarimetric Pi-SAR image
azimuth
range
study area
Shikotsu Lake
Tomakomai City
Tarumae Mt.
study area
Data acquired:7th, November, 2002
Data acquired:3rd, November, 2004
azimuth
range
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)
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
Fallen Trees After Typhoon
Ground-Truth Data
Amplitude Analysis
Image No. HH HV VV
L6407 67.1119 64.3982 66.1515
L8104 66.6437 64.4475 66.7929
L6407-L8104 0.4682 -0.0493 -0.6414
Site No. HH subtraction HV subtraction VV subtraction
196 0.8403 0.6001 -0.2851
197 0.9535 0.5802 -0.2825
198 0.8714 0.3279 -0.5437
217&218 0.8619 0.4444 -0.2188
243 0.8975 0.4549 -0.2435
245 0.9827 0.3009 -0.2797
267 0.9856 0.4899 -0.0584
271 0.8962 0.4392 -0.5062
300 0.8269 0.4759 -0.0099
302 0.7889 0.3169 -0.2331
268 0.6641 0.0218 -0.4429
303 0.5009 -0.0223 -0.6568
Test sites
Whole image
Amplitude Analysis Results
Accuracy:64.1%
Scattering Mechanisms From Forests
scattering from crown parts surface scattering
from ground
multiple reflection between ground and tree trunks/branches
multiple/volume scattering from branches
X/C-bandsL/P-bands
Three-Component Decomposition Analysis
Site No. Double subtraction Volume subtraction Surface subtraction
196 14.1248 1.1277 -22.1597
197 38.2798 1.0917 -39.4679
198 39.1910 0.4771 -34.9405
217&218 35.4332 0.7719 -32.1722
243 37.5858 0.7808 -34.0847
245 37.6906 0.4519 -25.9017
267 37.1895 0.9402 -32.4539
271 28.2527 0.8799 -27.4304
300 31.7851 0.8673 -31.1892
302 35.5875 0.4366 -27.3383
268 32.7751 -0.1122 -17.6746
303 33.6438 -0.2045 -27.5287
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.
Double Volume Surface
L6407 102.0232 138.2508 63.4812
L8104 74.4862 138.4537 83.7599
L6407-L8104 27.5449 -0.2026 -20.2847
Scattering Mechanism Analysis Result
Accuracy:77.7%
Pi-SAR
L-band antenna
X-band main antenna
X-band sub-antenna
Pi-SAR on Gulf Stream II X-band and L-band radomes
Two antennas within X-band main radomePartial Pol-InSAR by X-band main radome(Sub-antenna data not acquired this time)
Pi-SAR Data for Interferometric Analysis
X-band VM Pi-SAR image
Data acquired:3rd, August, 2004
Data acquired:3rd, November, 2004
M, N —— Moving window size
S —— Data
Complex Interferogram
Nii
Nii
Mjj
Mjjijij
Nii
Nii
Mjj
Mjjijij
Nii
Nii
Mjj
Mjjijij
SSSS
SS
*221*11
*21
Complex Degree of Coherence
Phase Image
Removal of Orbital Fringes
Courtesy of Dr. Moriyama
X7904X8104
Phase Unwrapping(X7904)
Phase Unwrapping(X8104)
Height Change
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.