• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.393-396
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• 2004

In this paper, multifrequency, polarimetric SAR data acquired during the first SIR-C/XSAR mission over the Seoul and Gyunggi-do (Korea) test sites are analyzed. The main objective of the study is to assess the possibility of extracting relevant information about surface properties for geophysical applications using polarimetry. This study analyses the characteristics of polarization responses and polarimetric parameters to conditions present in urban, river, agricultural, and forested areas. Results indicate that the dominant scattering property from these fields varies depending on the land cover types. The polarization response graphs and the backscattering coefficients associated with the polarimetric parameters are also useful in characterizing these cover types.

• Korean Journal of Remote Sensing
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• v.17 no.2
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• pp.141-153
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• 2001

A semi-empirical polarimetric backscattering model for bare soil surfaces is presented. Based on measurements by using polarimetric scatterometers and the JPL AirSAR, as well as the theoretical models, the backscattering coefficints $\sigma$$^0_w$, $\sigma$$^0_{hh}$ and $\sigma$$^0_{vh}$, and the parameters of the copolarized phase-difference probability density function, namely the degree of correlation $\alpha$ and the copolarized-phase-difference $\zeta$, are modeled empirically in terms of the volumetric soil moisture content m$_v$ and the surface roughness parameters $k_s$ and $k_l$, where k=2$\pi$f/c, s is the rms height and l is the correlation length.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.763-772
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• 2000

The Radiative Transfer Model(RTM) for computation of microwave polarimetric backscattering coefficients of a various types of vegitation canopies has been examined in this paper. Leaves in the vegitation canopy are modeled by rectangular resistive sheets, which sizes and orientations are randomly distributed. Surface roughness and soil moisture of soil surface are considered in this computation. The backscattering coefficients of grasslands are computed for various values of radar parameters and canopy parameters. A polarimetric scatterometer radar system at 15 GHz has been used for measurement of the scattering coefficient from a grass canopy and a cabbage canopy. The computation results obtained by the RTM for the canopies are compared with the measurement for examination of the RTM.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.33-36
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• 2008

This paper presents soil moisture retrieval from measured polarimetric backscattering coefficients of a vegetated surface. Based on the analysis of the quite complicate first-order radiative transfer scattering model for vegetated surfaces, a simplified scattering model is proposed for an inversion algorithm. Extraction of the surface-scatter component from the total scattering of a vegetation canopy is addressed using the simplified model, and also using the three-component decomposition technique. The backscattering coefficients are measured with a polarimetric L-band scatterometer during two months. At the same time, the biomasses, leaf moisture contents, and soil moisture contents are also measured. Then the measurement data are used to estimate the model parameters for vv-, hh-, and vh-polarizations. The scattering model for tall-grass-covered surfaces is inverted to retrieve the soil moisture content from the measurements using a genetic algorithm. The retrieved soil moisture contents agree quite well with the in-situ measured soil moisture data.

• Korean Journal of Remote Sensing
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• v.10 no.2
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• pp.17-35
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• 1994

A semi-empirical model for microwave polarimetric radar backscattering from bare soil surfaces was developed using polarmetric radar measurements and the knowledge based on the theoretical and numerical solutions. The microwave polarimetric backscatter measurements were conducted for bare soil surfaces under a variety of roughness and moisture conditions at L-, C-, and X-band frequencies at incidence angles ranging from 10` to 70`. Since the accrate target parameters as well as the radar parameters are necessary for radar scattering modeling, a complete and accurate set of ground truth data were also collected using a laser profile meter and dielectric probes for each surface condition, from which accurate measurements were made of the rms height, correlation length, and dielectric constant. At first, the angular and spectral dependencies of the measured radar backscatter for a wide range of roughnesses and moisture conditions are examined. Then, the measured scattering behavior was tested using theoretical and numerical solutions. Based on the experimental observations and the theoretical and numerical solutions, a semi-empirical model was developed for backscattering coeffients in terms of the surface roughness parameters and the relative dielectric constant of the soil surface. The model was found to yield very good agreement with the backscattering measurements of this study as well as with independent measurements.

• Korean Journal of Remote Sensing
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• v.38 no.5_2
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• pp.737-746
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• 2022

Utilizing weather independent SAR images along with machine learning based object detector is effective in robust vessel monitoring. While conventional SAR images often applied amplitude data from Single Look Complex, exploitation of polarimetric parameters acquired from multiple polarimetric SAR images was yet to be implemented to vessel detection utilizing machine learning. Hence, this study used four polarimetric parameters (H, p₁, DoP, DPRVI) retrieved from eigen-decomposition and two backscattering coefficients (γ₀, _VV, γ₀, _VH) from radiometric calibration; six bands in total were respectively exploited from 52 Sentinel-1 SAR images, accompanied by vessel training data extracted from AIS information which corresponds to acquisition time span of the SAR image. Evaluating different cases of combination, the use of polarimetric indexes along with amplitude values derived enhanced vessel detection performances than that of utilizing amplitude values exclusively.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.79.1-79.1
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• 2014

We present the result of near-infrared (near-IR) imaging polarimetry of star-forming regions in the Large Magellanic Cloud (LMC). We compiled near-IR photometric and polarimetric data of N159/160 regions. The photometric and polarimetric data were simultaneously obtained in J, H, and Ks bands using SIRPOL, an imaging polarimeter of the InfraRed Survey Facility (IRSF), in 2007 February. We measured Stokes parameters of point-like sources to derive their degree of polarization and polarization position angles. In this poster, we present polarization properties of these star-forming regions. We also discuss the polarization structure in these regions compared with mid-infrared dust emission structure from the Spitzer SAGE survey.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.435-440
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• 2002

The objective of this study is to analyze the relationship between polarimetric radar backscatters and stand characteristics over the mountainous forest area. L- and P-band full polarimetric airborne SAR data obtained in September 2000 were processed to compare with forest stand maps and ground collected stand variables. After the geometric registration of SAR image, mean radar backscatters were extracted for those ground plots where the stand parameters, such as tree height, DBH, and basal area, were measured during and after the SAR data acquisition. Preliminary analysis was focused on the topographic influence of radar backscattering under the homogeneous forest stand condition. Topographic effects, assessed by the local incidence angles, were different obvious in L-band data while it was not clear with P-band data.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.176-181
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• 2003

이 논문은 나대지에서 획득한 polarimetric SAR 자료의 후방 산란 계수(backscattering coefficient) 분석을 위한 surface parameters 추출 및 forward mapping에 대하여 서술하였다. Surface parameter는 토양의 거칠기(ks), 수분 함량(m/sub v/), 유전 상수(ε/sub m/) 등이 포함되어 있고, 유전 상수의 추정을 위하여 0.3-1.3GHz 구간의 자료를 기반으로 제안된 N. R. Peplinski의 경험상의 모델(Empirical Model) 알고리즘을 사용하였다. 추정된 surface parameter는 polarimetric SAR 자료의 산란 현상을 특징짓기 위한 forward mapping의 입력 값으로 이용되었으며, scattering model로 Oh의 경험상의 모델을 사용하였다. 각각의 surface parameter ks, θ, m/sub v/는 Oh 모델을 이용한 시뮬레이션을 통하여 레이더 후방 산란 계수에 미치는 영향에 대하여 조사되었다.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.180-185
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• 1998

Microwave polarimetric backscattering from a various types of grassland canopies has been analyzed by using the first-order radiative transfer theory in this paper. Leaves in the grassland are modeled by rectangular resistive sheets, which sizes (widths and lengths) and orientations (elevation and azimuth angles) are randomly distributed. Surface roughness and soil moisture of the ground plane under the grass canopy is considered in this computation. The backscattering coefficients of grasslands are computed for different radar parameters (angles, frequencies and Polarizations) as well as different canopy Parameters (size and orientation distributions of leaves, canopy depth, moisture contents of leaves and soil, rms height and correlation length of soil surface). A radar system for 15GHz has been fabricated and used for measurement of the scattering coefficient from a grass canopy. The computation result obtained by the scattering model for the grass canopy is compared with the measurements.