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Classification of Typhoon-Destroyed Forests Based on Tree Height Change Detection Using InSAR Technology IGARSS 2011 Haipeng Wang 1 , Kazuo Ouchi 2 , and Ya-Qiu Jin 1 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 T his S tudy
Tomakomai National Forests Shikotsu Lake Larch Todo Fir Red Pine Spruce
Pi-SAR Pi-SAR ( P olarimetric i nterferometric - 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
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:7 th , 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
Scattering Mechanisms From Forests sc attering from crown parts surface scattering from ground multiple reflection betw een ground and tree trunks/branches multiple/volume scattering from branches X/C-bands L/P-bands
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 radome Partial 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:3 rd , August, 2004 Data acquired:3rd, November, 2004
M , N —— Moving window size S —— Data Complex Interferogram Complex Degree of Coherence
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.