| 1.
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Sato, Koichi ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio
概要:
In this paper, we examine the polarimetric characteristics and the potential of the coherent decomposition in polarimetric synthetic aperture radar(SAR) interferometry. Coherent scattering decomposition based on the coherence
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optimization can separate effective phase center of different scattering mechanisms and can be used to generate canopy digital elevation model(DEM). This decomposition is applied to a simplified stochastic scattering model such as forest canopy. However, since the polarimetric characteristics are not well understood when the decomposition is carried out, we investigate its characteristics and potential using polarimetric entropy-alpha and three-component scattering matrix decomposition. The results show that the first and third components correspond to the lower and upper layer, respectively, in ideal case. In this investigation, SIR-C/X-SAR data of the Tien Shan flight-pass are used.
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| 2.
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Murase, Makoto ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
Tree canopies contain various scattering elements such as leaves, branches and trunks, which contribute to complex back-scattering, depending on frequency and polarization. In this paper, we propose to use the polarimetric correlation
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coefficient for classifying trees, forests, and vegetations. The polarimetric correlation coefficient can be derived by the elements of Sinclair scattering matrix. Since the scattering matrix can be defined in any polarization basis, we examined the coefficient in the linear HV, circular LR, and optimum polarization bases. First, the change of correlation coefficient inside trees along the range direction is examined using small trees in a laboratory. The wider the range, the better the index. The coefficient defined in the LR polarization basis showed the largest change within tree canopy, which also contribute to retrieve scattering mechanism. Second, this index for discrimination is applied to polarimetric SAR data sets(San Francisco and Briatia area) acquired by AIRSAR and SIR-C/X-SAR. It is shown that polarimetric correlation coefficient in the LR basis best serves to distinguish tree types.
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| 3.
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Yamada, Hiroyoshi ; Yamaguchi, Yoshio ; Kim, Yunjin ; Rodriguez, Ernesto ; Boerner, Wolfgang-Martin
概要:
Synthetic aperture radar interferometry have been established in the past two decades, and used extensively for many applications including topographic mapping of terrain and surface deformation. Vegetation analysis is also a
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growing area of its application. In this paper, we propose an polarimetric SAR interferometry technique for interferometric phase extraction of each local scatterer. The estimated position of local scattering centers has an important information for effective tree height estimation of forest. The proposed method formulated for local scattering center extraction is based on the ESPRIT algorithm which is known for high-resolution capability of closely located incident waves. The method shows high-resolution performance when local scattered waves are uncorrelated and have different polarization characteristics. Using the method, the number of dominant local scattering centers and interferometric phases in each image pixel can be estimated directly. Validity of the algorithm is demonstrated by using examples derived from SIR-C data.
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| 4.
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Yamaguchi, Yoshio ; Ishido, Motoi ; Yamada, Hiroyoshi ; Moriyama, Toshifumi
概要:
A four-component scattering model is proposed to decompose polarimetric synthetic aperture radar images. The covariance matrix approach is used to deal with the non-reflection symmetric scattering case. This scheme includes and
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extends the three-component decomposition method dealing with the reflection symmetry condition that the co-pol and the cross-pol correlations are close to zero. Circular polarization power is added as the fourth component to the three component scattering model which describes surface, double bounce, and volume scattering. This circular polarization term is added to take account of the co-pol and the cross-pol correlations which generally appear in complex urban area scatttering and disappear for natural distributed scatterer.
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| 5.
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Cui, Yi ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi ; Park, Sang-Eun
概要:
In this paper, we address the theoretical aspects of coherence region modeling and its inversion methods for polarimetric interferometric SAR (PolInSAR). Instead of only considering the geometrical shape of the coherence region, we
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focus on directly modeling the whitened interferometric cross-correlation matrix of the PolInSAR data. In particular, we consider three classes of generic scattering models that respectively contain single, double and triple phase centers within one resolution cell. We then demonstrate, for each class, that the modeled whitened interferometric cross-correlation matrix is normal. Based on this property, we propose, for each case, efficient algorithms to obtain the best normal matrix approximation solution for model inversion from the observed whitened interferometric cross-correlation matrix. In addition, we show how a simple and effective criterion can be designed from the derived solutions for model validation. Finally, we verify the solutions with both simulated and real data. The results prove the proposed method to be a very promising tool for PolInSAR applications.
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| 6.
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Yamaguchi, Yoshio ; Sato, Akinobu ; Boerner, Wolfgang Mart ; Sato, Ryoichi ; Yamada, Hiroyoshi
概要:
This paper presents an improvement to a decomposition scheme for accurate classification of polarimetric SAR images. Using a rotation of the coherency matrix to minimize the cross-polarized component, the four-component scattering
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power decomposition is applied to fully polarimetric SAR images. It is known that oriented urban area and vegetation signatures are decomposed into the same volume scattering mechanism in the previous decompositions and that it is difficult to distinguish vegetation from oblique urban areas with respect to radar direction of illumination within the volume scattering mechanism. It is desirable to distinguish these two scattering mechanisms for accurate classification although they exhibit similar polarimetric responses. The new decomposition scheme by implementing a rotation of coherency matrix first and subsequently the four-component decomposition yields considerably improved accurate results that oriented urban areas are recognized as double bounce objects from volume scattering.
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| 7.
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Yamada, Hiroyoshi ; Ozawa, Naoki ; Yamaguchi, Yoshio ; Hirano, Keizo ; Ito, Hiroyuki
概要:
Ocean surface current radar is a Doppler radar to observe oceanographic information using the Bragg scattering resonance mechanism. In this paper, we consider angular resolution improvement of the radar. The radar employs an
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antenna array with FMICW operation, then it can resolve angular distribution by Digital Beam Forming (DBF) and distance by Fourier transform of the beat signal obtained by the FMICW radar. In order to obtain sufficient angular resolution, large array length or aperture with increasing the number of elements is needed, that is often difficult to realize in the HF/VHF ocean surface current radar. In this paper we propose to apply the Khatri-Rao (KR) product array processing to the radar. To verify effectiveness of the KR product array processing in angular resolution enhancement for the ocean surface current radar, we apply the KR product array to actual experimental data set of the radar, and show that the method is available to angular resolution enhancement and Doppler spectrum improvement.
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| 8.
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Shirai, Satoshi ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio
概要:
In this paper, we study on direction-of-arrival (DOA) estimation error reduction by Khatri-Rao (KR) product extended array in the presence of correlated waves. Recently, a simple array signal processing technique called KR product extended
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array has been proposed. By using the technique, degrees-of-freedom of an array can be easily increased. However, DOA estimation accuracy deteriorates when correlated or coherent waves arrive. Such highly correlated waves often arrive for radar application, hence error reduction technique has been desired. Therefore, in this paper, we propose a new method for error reduction preprocessing scheme by using N-th root of matrix. The N-th root of matrix has a similar effect to the spatial smoothing preprocessing for highly correlated signals. As a result, DOA estimation error due to signal correlation will be reduced. The optimal order of N depends on the data itself. In this paper, a simple iterative method to obtain adaptive N is also proposed. Computer simulation results are provided to show performance of the proposed method.
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| 9.
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Cheng, Tzu-Yu ; Yamaguchi, Yoshio ; Chen, Kun-Shan ; Lee, Jong-Sen ; Cui, Yi
概要:
In this paper, a multi-temporal analysis of polarimetric synthetic aperture radar (Pol-SAR) data over the sandbank and oyster farm area is presented. Specifically, a four-component scattering model, being able to identify single
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bounce, double bounce, volume, and helix scattering power contributions, has been employed to retrieve information. Decomposition results of a time series RADARSAT Pol-SAR images acquired over the western Taiwan coast indicate that the coastal tide level plays a key role in the sandbank and oyster farm monitoring. At high tide levels, the underlying sandbank creates a shallow area with an increased roughness of the above sea surface, leading to an enhanced surface scattering power as compared to the ambient water. Contrarily, at low tide levels, the exposed sandbank appears to be a smooth scatterer, generating decreased backscattering power than the surrounding area. On the other hand, the double-bounce scattering power is shown to be highly correlated with the tide level in the oyster farms due to their vertical structures. This also demonstrates a promising potential of the four-component scattering power decomposition for coastal tide level monitoring applications.
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| 10.
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論文(リポジトリ)
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Yamada, Hiroyoshi ; Sakai, Hiroshi ; Yamaguchi, Yoshio
概要:
High resolution direction-of-arrival (DOA) estimation algorithm for array antennas becomes popular in these days. However, there are several error factors such as mutual coupling among the elements in actual array. Hence array
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calibration is indispensable to realize intrinsic performance of the algorithm. In the many applications, it is preferable that the calibration can be done in the practical environment in operation. In such a case, the incident wave becomes coherent multipath wave. Calibration of array in the multipath environment is a hard problem, even when DOA of elementary waves is known. To realize array calibration in the multipath environment will be useful for some applications even if reference signals are required. In this report, we consider property of reference waves in the multipath environment and derive a new calibration technique by using the multipath coherent reference waves. The reference wave depends on not only the DOA but also complex amplitude of each elementary wave. However, the proposed technique depends on the DOA only. This is the main advantage of the technique. Simulation results confirm the effectiveness of the proposed technique.
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| 11.
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Nakamura, Jun ; Aoyama, Kazuyasu ; Ikarashi, Muneyuki ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
This paper presents a coherent decomposition scheme for polarimetric SAR data. Coherent decomposition means the decomposition is applied to a single or a few scattering matrix data. Based on the scattering matrix acquired with an FM-CW
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polarimetric SAR system, we have devised a simple decomposition technique using the coherency matrix for the purpose of identifying scatterers. This paper presents the decomposition technique and some decomposition results obtained by a fully polarimetric FM-CW radar. It is shown the scattering mechanisms are well recovered and the orientation angles of wire scatterer are precisely measured.
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| 12.
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Suzuki, Junichiro ; Shoji, Yoshikazu ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio ; Tanabe, Masahiro
概要:
The multistage Wiener filter (MWF) outperforms the full rank Wiener filter in low sample support environments. However, the MWF adaptive process should be stopped at an optimum stage to get the best performance. There are two methods
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to stop the MWF adaptive process. One method is to calculate until the final full-stage, and the second method is to terminate at r-stage less than full-stage. The computational load is smaller in the latter method, however, a performance degradation is caused by an additional or subtractive stage calculation. Therefore, it is very important for the r-stage calculation to stop an adaptive process at the optimum stage. In this paper, we propose a simple method based on a cross-correlation coefficient to stop the MWF adaptive process. Because its coefficient is calculated by the MWF forward recursion, the optimum stage is determined automatically and additional calculations are avoided. The performance was evaluated by simulation examples, demonstrating the superiority of the proposed method.
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| 13.
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Inomata, Kenji ; Hirai, Takashi ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
This paper presents a target location estimation method that can use a pair of leaky coaxial cables to determine the 2D coordinates of the target. Since convention location techniques using leaky coaxial cables can find a target
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location along the cable in 1D, they have been unable to locate it in 2D planes. The proposed method enables us to estimate target on a 2D plane using; 1) a beam-forming technique and 2) a reconstruction technique based on Hough transform. Leaky coaxial cables are equipped with numerous slots at regular interval, which can be utilized as antenna arrays that acts both as transmitters and receivers. By completely exploiting this specific characteristic of leaky coaxial cables, we carried out an antenna array analysis that performs in a beam-forming fashion. Simulation and experimental results support the effectiveness of the proposed target location method.
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| 14.
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論文(リポジトリ)
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Yamaguchi, Yoshio ; Yamamoto, Yukari ; Yamada, Hiroyoshi ; Yang, Jian ; Boerner, Wolfgang-Martin
概要:
Classification of terrain is one of the most important applications of Polarimetric Synthetic Aperture Radar (POLSAR) image analysis. This paper presents a simple method to classify terrain by the use of the correlation
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coefficients in the circular polarization basis together with the total power of the scattering matrix in the X-band. The reflection symmetry condition that the co-polarized and the cross-polarized correlations are close to zero for natural distributed scatterers is utilized to extract characteristic parameters of small forests or cluster of trees, and oriented urban building blocks with respect to the direction of the radar illumination. Both of these kinds of scatterers are difficult to identify in high resolution POLSAR images of complex urban areas. The indices employed here are the correlation coefficient, a modified coefficient normalized by the reflection symmetric conditional case, and the total power. It is shown that forest areas and oriented building blocks are easily detected and identified. The terrain classification yielded by these combinations is very accurate as confirmed by photographic ground truth images.
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| 15.
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論文(リポジトリ)
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Yamada, Hiroyoshi ; Morishita, Masayuki ; Yamaguchi, Yoshio
概要:
High-resolution Direction-of-Arrival (DOA) estimation techniques for antenna arrays have been widely desired in many applications such as smart antennas, RF position location, and RFID system. To realize high-resolution capability of the
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techniques, precise array calibration is necessary. For an array of single-mode elements, a calibration matrix derived by the open-circuit method is the simplest one. Unfortunately, calibration performance of the method is not enough for the high-reslution DOA estimation techniques. In this paper, we consider problems of the calibration matrix derived by the method, and show that errors in the matrix can be effectively removed by an optimal diagonal weight coefficient. In the proposed compensation technique, the number of newly introduced parameters, or unknowns, is only one for an array of the identical elements. Performance of the simple compensation technique is verified numerically and experimentally.
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| 16.
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論文(リポジトリ)
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Endo, Natsumi ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio
概要:
Direction of arrival estimation of coherent multipath waves by using superresolution technique often requires decorrelation preprocessings. Spatial smoothing preprocessings are the most popular schemes as the techniques. In
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mobile environment, position change of the target/transmitter often brings us decorrelation effect. In addition, multiple signals transmitted by an antenna array, such as a MIMO transmitter, can also cause the same effect. These effects can be categorized as the spatial smoothing preprocessing at the transmitter. In this paper, we analyze the spatial smoothing effect at the transmitter in the presence of multipath coherent waves. Theoretical and simulation results show that the spatial smoothing at the transmitter has a good feature in comparison with the conventional SSP at the receiving array. We also show that better decorrelation performance can be obtained when the SSPs at the transmitter and receiving array are applied simultaneously.
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| 17.
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論文(リポジトリ)
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Sato, Ryoichi ; Yajima, Yuki ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
This paper examines seasonal change of the true water area of Lake Sakata by using Polarimetric Synthetic Aperture Radar (POLSAR) image analysis. The true water area includes not only the body of water but also the water area under
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emerged-plants and/or floating-leave plants in the lake. Statistical POLSAR image analysis is carried out for both X- and L-band data, based on the three-component scattering power decomposition method, where the decomposed components are surface scattering, double-bounce scattering and volume scattering components. From the results of the image analysis for the L-band POLSAR data acquired by Pi-SAR system, it is found that strong double-bounce scattering can be observed at the vicinity of the boundary region between water area and the surrounding emerged-plants area in early and middle summer. This phenomenon is an important factor for environmental monitoring. To verify the generating mechanism of the double-bounce scattering, the Finite-Difference Time-Domain (FDTD) polarimetric scattering analysis is also executed for a simplified boundary model, which simulates the local boundary region around the lake and consists of lots of vertical thin dielectric pillars on a perfect electric conductor (PEC) plate or on a PEC and dielectric hybrid plate. Taking into account the polarimetric feature of the double-bounce scattering obtained by both the FDTD and POLSAR image analyses, one can distinguish the actual water area from the bush of the emerged-plants around the lake, even when the water area is concealed by emerged-plants and/or floating-leave plants. Consequently, it is found that by using the proposed approach, one can estimate the true water area seasonal change for the lake and the surrounding wetland.
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| 18.
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Iura, Hiroki ; Yamada, Hiroyoshi ; Ogawa, Yasutaka ; Yamaguchi, Yoshio
概要:
Antenna array is essential factor for multiple- input multiple-output (MIMO) wireless systems. Since the antenna array i
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s composed of closely spaced elements, the mutual coupling among the elements cannot be ignored for the best performance of the array. Mutual coupling affects the MIMO channel, so the performance of a MIMO system, including channel capacity and diversity, varies with the degree of mutual coupling. The effect of mutual coupling is a function of the antenna load impedance. Therefore, designing an optimal element-matched array for a MIMO system requires consideration of the optimal matching condition for the array elements, the one that maximizes the channel capacity. We evaluated the effects of mutual coupling with various matching conditions in dipole arrays, and investigated their effects on the path correlation and channel capacity of MIMO systems. Simulation showed that the conventional conjugate matching of each element is still suitable for closely spaced elements except when the separation is about less than 0.1λ. Theoretical consideration of the received power of a closely-spaced-element array is also provided to show the effects of mutual coupling.
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| 19.
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Hayashi, Kei ; Sato, Ryoichi ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
This paper examines polarimetric scattering characteristics caused by a dihedral corner reflector of finite size. The dihedral corner reflector is a basic model of double-bounce structure in urban area. The detailed scattering information
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serves the interpretation of Polarimetric Synthetic Aperture Radar (POLSAR) data analysis. The Finite-Difference Time-Domain (FDTD) method is utilized for the scattering calculation because of its simplicity and flexibility in the target shape modeling. This paper points out that there exists a stable double-bounce squint angle region both for perfect electric conductor (PEC) and dielectric corner reflectors. Beyond this stable squint angular region, the scattering characteristics become completely different from the assumed response. A criterion on the double-bounce scattering is proposed based on the physical optics (PO) approximation. The detailed analyses on the polarimetric index (copolarization ratio) with respect to squint angle and an experimental result measured in an anechoic chamber are shown.
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| 20.
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Moriyama, Toshifumi ; Yamaguchi, Yoshio ; Uratsuka, Seiho ; Umehara, Toshihiko ; Maeno, Hideo ; Satake, Makoto ; Nadai, Akitsugu ; Nakamura, Kazuki
概要:
This paper attempts to use the polarimetric correlation coefficient for extraction of the polarimetric features of the urban areas and the natural distributed areas from Polarimetric Synthetic Aperture Radar (POLSAR) data.
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There is a possibility that the polarimetric correlation coefficient can reveal various scattering mechanisms of terrains based on the reflection symmetry property. In order to verify the capability of polarimetric correlation coefficient, we examined the behavior of this coefficient of the urban areas and the natural distributed areas with respect to the several polarimetric scattering models in the linear and circular polarization bases, and the difference of the polarimetric scattering characteristics between these two areas was derived. It was confirmed that the polarimetric correlation coefficient is useful to extract the polarimetric features from the actual L-band and X-band POLSAR data.
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| 21.
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Kimura, Koji ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
This paper takes full advantage of polarimetric scattering parameters and total power to classify polarimetric SAR image data. The parameters employed here are total power, polarimetric entropy, and averaged alpha angle (alphabar). Since
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these parameters are independent each other and represent all the scattering characteristics, they seem to be one of the best combinations to classify Polarimetric Synthetic Aperture Radar (POLSAR) images. Using unsupervised classification scheme with iterative Maximum Likelihood classifier, it is possible to decompose multi-look averaged coherency matrix with complex Wishart distribution effectively. The classification results are shown using Pi-SAR image data set comparing with other representative methods.
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| 22.
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Kimura, Koji ; Yamaguchi, Yoshio ; Moriyama, Toshifumi ; Yamada, Hiroyoshi
概要:
This paper proposes a method to detect buildings and houses whose walls are not parallel to Synthetic Aperture Radar (SAR) flight path. Experimental observations show that it is difficult to detect these targets because of small
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backscattering characteristics. The detection method is based on the correlation coefficient in the circular polarization basis, taking full advantage of Polarimetric SAR (POLSAR) data. Since the correlation coefficient is real-valued for natural distributed targets with reflection symmetry and for non-natural targets orthogonal to illumination direction, and it becomes a complex number for non-natural targets aligned not orthogonal to radar Line-Of-Sight (LOS), the value seems to be an effective index for detection of obliquely aligned non-natural targets. The detection results are shown using the X-band Polarimetric and Interferometric SAR (Pi-SAR) single-path data set in conjunction with other polarimetric indices.
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| 23.
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Sato, Koichi ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio
概要:
Polarimetric SAR interferometry has been successful and attractive for forest, parameters (tree height and canopy extinction) estimation. In this paper, we propose to use the ESPRIT algorithm to extract the interferomotric phase of
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local scatterers with polarimetric and interferometric he SAR data. Two or three local scattering waves can be (extracted at each image patch when a fully polarimetric data set (HH, HV, VV) is available. Furthermore, the KSPRIT can estimate two dominant, local scattering centers when only a dual polarimetric data set(e.g., VV and VH) is provided. In order to demonstrate effectiveness the proposed technqiue, we examined the relation between local scattering centers extracted by this method and complex coherence of the coherent scattering model for vegetation cover. The results show that, the three-wave estimation can be more accurate than the two-wave case. The extracted interferometric phases with full and dual polarization data sets correspond to effective ground and canopy scattering centers. In this investigation. SIR-C/X-SAR data of the Tien Shan flight-pass are used.
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| 24.
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Yang, Jian ; Peng, Ying-Ning ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi ; Boerner, Wolfgang-Martin
概要:
The periodicity of a target scattering matrix is studied when the target is rotated about the sight line of a monostatic radar. Except for the periodicity and invariance of the scattering matrix diag(a, a), it is proved that only
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helixes have the quasi-invariance, and that only N-targets have the quasi-periodicity, demonstrating that a target with some angle rotation symmetry also has the scattering matrix form diag(a, a). From this result, we conclude that it is impossible to extract the shape characteristics of a complex target from its scattering matrix or its Kennaugh matrix.
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| 25.
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Kitayama, Kenji ; Yamaguchi, Yoshio ; Yang, Jian ; Yamada, Hiroyoshi
概要:
The Sinclair scattering matrix is defined in a fixed radar range. If a radar target extends in the range direction, the reflected signal or the compound scattering matrix will undergo interaction of multiple reflections. Sinece
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scattering matrix is subject to target parameters such as shape, size, orientation, material, and redar paramenters as frequency, polarization, and incidence angle, it is difficult to specify a representative scattering matrix of a general target. Therefore we choose the simplest target, wire, and its scattering matrix to examine the effect of targets aligned in the range direction with respect to the compoud scattering matrix. First, we present a simple formula for the compound scttering matrix of wires with the phase difference due to spacing. Then, we employed the FDTD method to exmine the scattering phenomena, changing the spacing in the range direction. The FDTD result reveals that two wires can become sphere (plate) and dihedral corner reflector (diplane) component generators; and that four wires can become a good helix component generator. These phenemena are verified with a laboratory measurement. From the result, the traget decomposition should be carefully carried out in terms of range. If a range resolution of a radar is not high enough, the scattering matrix of the desired target may be affected by the targets behind.
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| 26.
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Boerner, Wolfgang-Martin ; Yamaguchi, Yoshio
概要:
The development of Radar Polarimetry and Radar Interferometry is advancing rapidly. Whereas with radar polarimetry, the textural fine-structure, target orientation, symmetries and material constituents can be recovered with
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considerable improvement above that of standard amplitude-only radar; with radar interferometry the spatial(in depth)structure can be explored. In Polarimetric Interferometric Synthetic Aperture Radar(POL-IN-SAR)Imaging, it is possible to recover such co-registered textural and spatial information from POL-IN-SAR digital image data sets simultaneously, including the extraction of Digital Elevation Maps(DEM) from either Polarimetric(scattering matrix)or Interferometric(single platform: dual antenna)SAR systems. Simultaneous Polarimetric-plus-Interferometric SAR offers the additional benefit of obtaining co-registered textural-plus-spatial three-dimensional POL-IN-DEM information, which when applied to Repeat-Pass Image-Overlay Interferometry provides differential background validation, stress assessment and environmental stress-change information with high accuracy. Then, by either designing Multiple Dual-Polarization Antenna POL-IN-SAR systems or by applying advanced POL-IN-SAR image compression techniques, it will result in POL-arimetric TOMO-graphic(Multi-Inter-ferometric)SAR or POL-TOMO-SAR Imaging. This is of direct relevance to local-to-global environmental background validation, stress assessment and stress-change monitoring of the terrestrial and planetary covers.
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| 27.
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Moriyama, Toshifumi ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
This paper presents a three-dimensional polarimetric detection result of targets buried in snowpack by synthetic aperture FM-CW radar system. Since the FM-CW radar is suitable for short range sensing and can be equipped with fully
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polarimetric capability, we further extended it to a polarimetric three-dimensional SAR system. A field experiment was carried out to image and detect targets in a natural snowpack of 280 cm deep. The polarimetric detection and identification schemes are the polarimetric filtering, three-component decomposition, and the power polarization anisotropy coefficient. These approaches to acquired data show the usefulness of three-dimensional polarimetric FM-CW SAR system.
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| 28.
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Singh, Dharmendra ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi ; Singh, Keshev Prasad
概要:
This paper describes an individual effect of soil moisture(m_g)and surface roughness(h_<rms>)of bare soil on the back sc
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attering coefficient(σ^0)at the X-band frequency. The study contributes to the design of an efficient microwave sensor. For this purpose, experimentally observed data was utilized to provide a composite σ^0 equation model accounting for individual effect in regression analysis. The experimental data are compared with Small Perturbation Method. It is observed that the X-band gives better agreement up to incidence angle 50゜ for HH-polarization and 60゜ for VV-polarization as compared to the C-band. The lower angles of incidence give better results than the higher angles for observing m_g at the X-band. The multiple and partial regression analyses have also carried out for predicting the dependence of scattering coefficient(σ^0)on m_g and h_<rms> more accurately. The analyses suggest that the dependence of dielectric constant(i.e., m_g)is much more significant in comparison to surface roughness at lower angles of incidence for both like polarizations. The results propose the suitable angle of incidence for observing bare surface roughness and soil moisture at the X-band. All these data can be used as a reference for satellite or spaceborne sensors.
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| 29.
論文(リポジトリ) |
論文(リポジトリ)
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Yamaguchi, Yoshio ; Moriyama, Toshifumi ; Ishido, Motoi ; Yamada, Hiroyoshi
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| 30.
論文(リポジトリ) |
論文(リポジトリ)
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Shimoda, Hiroki ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
This paper pursuits a possibility of fully polarimetric and threedimensional (3-D) imaging by Holographic Synthetic Aperture Radar Tomography (HoloSAR). HoloSAR is 3-D extension of Circular Synthetic Aperture Radar (CSAR) along the
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vertical direction whose trajectory is a circle in a horizontal plane. By adding fully polarimetric capability to HoloSAR, it becomes a perfect 3-D imaging radar system which reveals scattering mechanisms from object through scattering power decomposition. This paper attempts to achieve such a prototype system in an anechoic chamber. The experimental result successfully yielded a 3-D image reconstruction of objects with exhibiting polarimetric scattering mechanism.
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| 31.
論文(リポジトリ) |
論文(リポジトリ)
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Umemura, Maito ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
Polarimetric similarity is a parameter for measuring the similarity between two scattering mechanisms. In this paper, we
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propose a novel model-based target classification technique using a compensated polarimetric similarity parameter between two coherency matrices. In general, the ensemble average coherency matrix elements have magnitude imbalance, thus the contribution degree to the polarimetric similarity differs for each element. We illustrate how to compensate the contribution degree, and then the proposed method is tested on L-band fully polarimetric ALOS-2/PALSAR-2 data sets by using 4 theoretical scattering models (surface scattering, double-bounce scattering, volume scattering, and 22.5ﾟ oriented dihedral scattering). The classification results show that the new compensation scheme serves to better classification.
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| 32.
論文(リポジトリ) |
論文(リポジトリ)
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Yamaguchi, Yoshio ; Umemura, Maito ; Kanai, Daichi ; Miyazaki, Kosuke ; Yamada, Hiroyoshi
概要:
This paper reports prompt space-borne ALOS-2 SAR observation results of Hokkaido-Iburi-Tobu earthquake on 2018/09/06. Emphasis is placed on quick survey for disaster monitoring using fully polarimetric data. On 2018/09/08, ALOS-2 has
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acquired data over the disaster area. By comparison of the previous data (2017/08/26) before the earthquake, damaged areas by landslides are clearly detected. The analysis is based on the scattering power decomposition, which retrieves scattering mechanism change from bare soil surface caused by landslide and serves to identify the landslide location. The decomposition and anisotropy images are presented to show the effectiveness of fully polarimetric SAR sensing from space.
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| 33.
論文(リポジトリ) |
論文(リポジトリ)
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Yamaguchi, Yoshio ; Minetani, Yuto ; Umemura, Maito ; Yamada, Hiroyoshi
概要:
This paper presents a conifer and broad-leaf tree classification scheme that processes high resolution polarimetric synthetic aperture data above X-band. To validate the proposal, fully polarimetric measurements are conducted in a
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precisely controlled environment to examine the difference between the scattering mechanisms of conifer and broad-leaf trees at 15 GHz. With 3.75 cm range resolution, scattering matrices of two tree types were measured by a vector network analyzer. Polarimetric analyses using the 4-component scattering power decomposition and alpha-bar angle of eigenvalue decomposition yielded clear distinction between the two tree types. This scheme was also applied to an X-band Pi-SAR2 data set. The results confirm that it is possible to distinguish between tree types using fully polarimetric and high-resolution data above X-band.
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| 34.
論文(リポジトリ) |
論文(リポジトリ)
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Ishikuro, Takanori ; Sato, Ryoichi ; Yamaguchi, Yoshio ; Yamada, Hiroyoshi
概要:
In this paper, we propose a simple algorithm for detecting a vehicle trapped in flooded urban area by using quad-polarimetric SAR data. The four-component scattering power decomposition and phase difference of HH-VV co-pol ratio are
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effectively used in the proposed algorithm. Here we carry out polarimetric scattering measurement for a scaled vehicle model surrounded by two buildings model in an anechoic chamber, to acquire the quad-polarimetric SAR data. It is confirmed from the results of the image analysis for the measured SAR data that the proposed algorithm for vehicle detection works well even under severe environment where the vehicle is set in the shadow of the building and/or the alignment of the vehicle or the buildings is obliquely oriented to direction of the radar line of sight.
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| 35.
論文(リポジトリ) |
論文(リポジトリ)
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Singh, Gulab ; Yamaguchi, Yoshio ; Boerner, Wolfgang-Martin ; Park, Sang-Eun
概要:
This paper reflects the polarimetric synthetic aperture radar (POLSAR) data utilization for near-real time earthquake an
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d/or tsunami damage assessment in urban areas. In order to show the potential of the fully polarimetric high resolution polarimetric SAR (POLSAR) image data sets, a four-component scattering power decomposition scheme has been developed and applied to monitor near-real time earthquake and tsunami disaster damages. The test site for natural disaster damages has been selected parts of the coastal area affected by the March 11, 2011 9.0 magnitude earthquake that struck off Japan’s northeastern coast and triggered a super- tsunami. The color-coded images of the scattering power decomposition scheme are simple and straightforward tool to interpret the changes over the earthquake/tsunami affected urban areas and man-made infrastructures. This method also holds other types of natural (typhoon or tornado) and manmade disaster assessments application. It is found that the double bounce scattering power is the most promising of the input parameters to detect automated disaster affected urban areas at pixel level. It is also observed that the very high resolution POLSAR images are required for superior urban area monitoring over the oriented urban blocks with respect to the illumination of radar.
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| 36.
論文(リポジトリ) |
論文(リポジトリ)
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Yamaguchi, Yoshio
概要:
This paper presents scattering power decomposition images of fully polarimetric synthetic aperture radar data for disast
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er monitoring. Utilization of fully polarimetric data can derive full color images with red–green–blue color-coding, red for the double-bounce power, green for the volume scattering power, and blue for the surface scattering power, for which each color brightness corresponds to the magnitude. Since disaster events cause the changes of each scattering power, it becomes straightforward for everyone to recognize the changes of the color in the polarimetric decomposed images provided time series data sets are made available. After applying the four-component scattering power decomposition to fully polarimetric image data sets acquired with the Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR), several images are presented for natural disaster monitoring of volcanic activity, snow accumulation, landslides and tsunami effects caused by great earthquakes. It is seen in the polarimetric decomposition images that the surface scattering power becomes predominant in most disaster areas compared to those in normal situations.
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| 37.
論文(リポジトリ) |
論文(リポジトリ)
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Cui, Yi ; Yamaguchi, Yoshio ; Yang, Jian ; Park, Sang-Eun ; Kobayashi, Hirokazu ; Singh, Gulab
概要:
In this paper, the three-component power decomposition for polarimetric SAR (PolSAR) data with an adaptive volume scattering model is proposed. The volume scattering model is assumed to be reflection-symmetric but parameterized. For
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each image pixel, the decomposition first starts with determining the adaptive parameter based on matrix similarity metric. Then, a respective scattering power component is retrieved with the established procedure. It has been shown that the proposed method leads to complete elimination of negative powers as the result of the adaptive volume scattering model. Experiments with the PolSAR data from both the NASA/JPL (National Aeronautics and Space Administration/Jet Propulsion Laboratory) Airborne SAR (AIRSAR) and the JAXA (Japan Aerospace Exploration Agency) ALOS-PALSAR also demonstrate that the proposed method not only obtains similar/better results in vegetated areas as compared to the existing Freeman-Durden decomposition but helps to improve discrimination of the urban regions.
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| 38.
論文(リポジトリ) |
論文(リポジトリ)
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Kobayashi, Shoko ; Omura, Yoshiharu ; Sanga-Ngoie, Kazadi ; Widyorini, Ragil ; Kawai, Shuichi ; Supriadi, Bambang ; Yamaguchi, Yoshio
概要:
A decomposition scheme was applied to ALOS/PALSAR data obtained from a fast-growing tree plantation in Sumatra, Indonesia to extract tree stem information and then estimate the forest stand volume. The scattering power
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decomposition of the polarimetric SAR data was performed both with and without a rotation matrix and compared to the following field-measured forest biometric parameters: tree diameter, tree height and stand volume. The analytical results involving the rotation matrix correlated better than those without the rotation matrix even for natural scattering surfaces within the forests. Our primary finding was that all of the decomposition powers from the rotated matrix correlated significantly to the forest biometric parameters when divided by the total power. The surface scattering ratio of the total power markedly decreased with the forest growth, whereas the canopy and double-bounce scattering ratios increased. The observations of the decomposition powers were consistent with the tree growth characteristics. Consequently, we found a significant logarithmic relationship between the decomposition powers and the forest biometric parameters that can potentially be used to estimate the forest stand volume.
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| 39.
論文(リポジトリ) |
論文(リポジトリ)
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Itabashi, Shinji ; Yamada, Hiroyoshi ; Nishimori, Kentaro ; Yamaguchi, Yoshio
概要:
Recently, researches on radio wave security sensors by using array antenna or MIMO(Multiple-Input Multiple Output) system have been attracting attention. These sensors utilize the property that MIMO channel matrix is sensitive to the
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propagation environment change in indoor multipath environment. Now the property is used for event detection, such as intrusion, by calculating correlation of MIMO channel matrices. Fundamental study has been performed, however, statistical property, or quantitative detection performance analysis, of the sensor was still remain to be clarified. So, our objective is to derive a probability density function (PDF) of the correlation coefficient and to demonstrate them experimentally. The PDF is a key function to derive detection rate and so on. In the conventional MIMO sensor, correlation coefficient of the channel matrix between with and without an event is used as a measure of events. Therefore, in this report we will derive the PDF of the channel correlation used in the conventional MIMO sensor theoretically and also show the validity by experimental results.
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| 40.
論文(リポジトリ) |
論文(リポジトリ)
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Cui, Yi ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio
概要:
This paper investigates the parameter estimation of compound Wishart distribution for statistical modeling of polarimetric synthetic aperture radar data. We show that the recently proposed method of matrix log-cumulant may lead
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to non-invertible equations and cause unstable performances. In order to overcome such difficulty, we proposed a Bayesian-based method to re-estimate the log-cumulants. Simulation experiment demonstrates that the proposed algorithm provides both improved and stabler results. Finally, we present an application of the new method for texture analysis of the Germany F-SAR polarimetric data.
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| 41.
論文(リポジトリ) |
論文(リポジトリ)
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Yamada, Toshihiro ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio
概要:
In this report, we provide preliminary results of experimental study on resolution enhancement of SAR tomography. The SAR tomography by using repeat-pass SAR images, or multi-baseline observa-tion, can be regarded as a
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multi-incident angle imaging array technique. Three-dimensional imaging can be realized with these SAR images (baseline data set) by using direction of arrival (DOA) estimation techniques, such as beamforming (BF) method. In the SAR tomography, limited number of base-lines is the most difficult problem. To overcome this difficulty, we propose to apply the Khatri-Rao (KR) product array processing to the SAR tomography which enhance the array aperture and improves the degrees-of-freedom of the array system. Simulation results are provided to show availability of the KR product array processing in SAR tomography. In addition, indoor X-band model experiments were done in an anechoic chamber of our laboratory to demonstrate performance of the proposed processing.
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| 42.
論文(リポジトリ) |
論文(リポジトリ)
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Ozawa, Naoki ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio ; Hirano, Keizo ; Ito, Hiroyuki
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| 43.
論文(リポジトリ) |
論文(リポジトリ)
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Shirai, Satoshi ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio
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| 44.
論文(リポジトリ) |
論文(リポジトリ)
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Cui, Yi ; Yamaguchi, Yoshio ; Yang, Jian ; Kobayashi, Hirokazu
概要:
International Symposium on Antennas and Propagation (ISAP 2012) : October 29 - November 2, 2012 Nagoya, Japan.
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| 45.
論文(リポジトリ) |
論文(リポジトリ)
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Chu, Chih-Yuan ; Cheng, Tzu-Yu ; Wang, Hsiu-Wen ; Chen, Kun-Shan ; Yamaguchi, Yoshio ; Lee, Jon-Sen
概要:
International Symposium on Antennas and Propagation (ISAP 2012) : October 29 - November 2, 2012 Nagoya, Japan.
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| 46.
論文(リポジトリ) |
論文(リポジトリ)
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Yamada, Hiroyoshi ; Tanaka, Kei ; Yamaguchi, Yoshio
概要:
This report discusses MIMO system as home security sensor. MIMO propagation channel is very sensitive to the environmental change. The proposed radio sensor called MIMO sensor utilizes this feature to detect events for home security. We
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report fundamental results for evaluation of array configuration and propagation channel.
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| 47.
論文(リポジトリ) |
論文(リポジトリ)
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Kumakura, Akira ; Yamada, Hiroyoshi ; Nishimori, Kentaro ; Yamaguchi, Yoshio
概要:
In recent years, researches on radio security sensors by using multi-antenna or MIMO system have been attracting attention. Many systems or algorithms have proposed. To evaluate various algorithms, statistical channel model for the
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system should be established. In this report, we analyze the channel model of the MIMO security sensor.
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| 48.
論文(リポジトリ) |
論文(リポジトリ)
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Ogawa, Ken ; Yamada, Hiroyoshi ; Kurosaki, Yuta ; Yamaguchi, Yoshio
概要:
Recently, several indoor intrusion/event detection methods using radio propagation change have been proposed. One of these methods with an array antenna employs SIMO system. Also, several methods use MIMO system. In this
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report, we propose a new detection method without channel estimation and compare its performance to the conventional ones.
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| 49.
論文(リポジトリ) |
論文(リポジトリ)
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Sugai, Kohei ; Yamada, Hiroyoshi ; Nishimori, Kentaro ; Yamaguchi, Yoshio
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| 50.
論文(リポジトリ) |
論文(リポジトリ)
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Kaneko, Kazuhiro ; Aoyagi, Takahiro ; Yamada, Hiroyoshi ; Yamaguchi, Yoshio
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