9 results on '"Sato, Motoyuki"'
Search Results
2. A Monostatic/Bistatic Ground-Based Synthetic Aperture Radar System for Target Imaging and 2-D Displacement Estimation.
- Author
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Wang, Suyun, Feng, Weike, Kikuta, Kazutaka, and Sato, Motoyuki
- Abstract
A monostatic/bistatic ground-based synthetic aperture radar (GB-SAR) system using an optical electric field sensor (OEFS) as the bistatic receiving unit has been designed for target imaging and 2-D displacement estimation purposes. The designed system has the capability of acquiring the monostatic and bistatic SAR images simultaneously from different looking angles, enabling the displacement vector estimation of the illuminated area. The spatial baseline between the monostatic and bistatic receivers is selected according to the estimation precision analysis. Experimental results are presented to evaluate the performance of the designed system and the proposed method. The displacement estimation accuracies in x- and y-directions can reach up to millimeter level. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. Urban Damage Level Mapping Based on Scattering Mechanism Investigation Using Fully Polarimetric SAR Data for the 3.11 East Japan Earthquake.
- Author
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Chen, Si-Wei, Wang, Xue-Song, and Sato, Motoyuki
- Subjects
SYNTHETIC aperture radar ,RADAR polarimetry ,EARTHQUAKE damage ,EARTHQUAKES ,TSUNAMI damage - Abstract
A quick response to a large-scale natural disaster such as earthquake and tsunami is vital to mitigate further loss. Remote sensing, especially the spaceborne sensors, provides the possibility to monitor a very large scale area in a short time and with regular revisit circle. Damage ranges and damage levels of the destructed urban areas are extremely important information for rescue planning after an event. Rapid mapping of the urban damage levels with synthetic aperture radar (SAR) is still challenging. Compared with single-polarization SAR, fully polarimetric SAR (PolSAR) has a better potential to understand the urban damage from the viewpoint of scattering mechanism investigation. In radar polarimetry, the dominant double-bounce scattering mechanism in an urban area is primarily induced by the ground-wall structures and can reflect the changes of these structures. In this sense, urban damage level in terms of destroyed ground-wall structures can be indicated by the reduction of the dominant double-bounce scattering mechanism, which is the basis of this study. This work first establishes and validates the linear relationship between the urban damage level and the proposed polarimetric damage index using polarimetric model-based decomposition. Then, efforts are focused on the development of a rapid urban damage level mapping technique which mainly includes two steps of urban area extraction and polarimetric damage level estimation. The 3.11 East Japan earthquake and tsunami inducing great-scale destruction are adopted for study using L-band multitemporal spaceborne PolSAR data. Experimental studies demonstrate that the estimated damage levels are closely consistent to the ground-truth. The final urban damage level map for the full scene is generated thereafter. Results achieved in this study further validate the necessity of exploring fully polarimetric technique for damage assessment. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
4. A Fundamental Study of Polarimetric GB-SAR for Nondestructive Inspection of Internal Damage in Concrete Walls.
- Author
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TAKAHASHI, KAZUNORI, OKAMURA, SAIKA, and SATO, MOTOYUKI
- Subjects
NONDESTRUCTIVE testing ,CONCRETE walls ,SYNTHETIC aperture radar ,ELECTRON beams ,PHOTOCATHODES - Abstract
SUMMARY Damages on the surfaces of concrete buildings can easily be detected by visual inspection and can be repaired. However, damages inside walls need nondestructive inspection techniques to be detected, located, and identified. There has been a great demand for such techniques particularly after the 3.11 Great East Japan Earthquake. Ground-based synthetic aperture radar (GB-SAR) is a technique that can be potentially used for inspection of concrete walls in a nondestructive and noncontacting manner. The paper reports a fundamental experiment with a polarimetric GB-SAR system to detect internal damage in a concrete specimen caused by horizontal loading simulating earthquakes. The results show that the system does not have enough resolution to visualize individual defects, and that the effect of steel rebars installed inside the concrete is so strong that it masks weak responses. However, polarimetric analysis demonstrated the capability to minimize the effect of rebars by rearranging polarization basis and to extract weak responses. In particular, internal damages could be detected by observing the volume scattering component in this experiment. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
5. Determination of Tsunami-affected areas by polarimetric SAR.
- Author
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Sato, Motoyuki and Chen, Si-Wei
- Abstract
SAR Interferometry is a common methodology for detection of Natural disaster affected area. However, we applied radar polarimetric analysis to ALOS/PALSRA data sets to investigate the possibility of detection of Tsunami affected area only from the SAR data acquired after the event. The resolution of the SAR image is 30m by 30m and cannot identify each house or buildings in the area. However, we have demonstrated that single-bonce and double-bounce scattering mechanism clearly shows the Tsunami affected area in Ishinomaki city, Japan, after the Great East Japan Earthquake and Tsunami. We could also showed that the standard deviation of the polarimetric orientation angle increases by the damage, and can be used for the measure of the damage. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
- View/download PDF
6. Uniform Polarimetric Matrix Rotation Theory and Its Applications.
- Author
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Si-Wei Chen, Xue-Song Wang, and Sato, Motoyuki
- Subjects
REMOTE sensing by radar ,POLARIMETRIC remote sensing ,SYNTHETIC aperture radar ,COVARIANCE matrices ,RADAR polarimetry - Abstract
This paper presents the development of a uniform polarimetric matrix rotation theory in the rotation domain along the radar line of sight for polarimetric synthetic aperture radar (PolSAR) data interpretation. The uniform representation of each coherency matrix element is a sinusoidal function in the rotation domain. A set of oscillation parameters, including oscillation amplitude, oscillation center, angular frequency, and initial angle, is proposed to fully characterize the scattering behavior in the rotation domain. A set of rotation angle parameters, including stationary angle, null angle, and minimization/maximization angles, is derived to indicate specific states of the rotation property. The rotation relationships between the coherency and covariance matrices with linear and circular polarization bases are established. A look-up table for these parameters is provided, and their physical meanings are interpreted. These derived parameters directly link to the Huynen parameters. Therefore, the proposed theory has the ability to achieve a desired state of one Huynen parameter by rotating the polarimetric matrix at a designated rotation angle. This theory also generalizes both the classic polarization orientation angle originally derived from the covariance matrix in a circular polarization basis and the deorientation theory developed from the minimization of the cross-polarization term. The roll-invariant terms have also been summarized. Finally, multifrequency Pi-SAR and AIRSAR PolSAR data sets are used to demonstrate the derived parameters. One oscillation amplitude parameter has been verified to be especially suitable for characterization of oriented man-made targets. Two angle parameters are sensitive to the reflection symmetry condition and crop types. Therefore, a simple unsupervised classification scheme has been developed and demonstrated. Further utilization perspectives of the proposed theory have been discussed. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
7. General Polarimetric Model-Based Decomposition for Coherency Matrix.
- Author
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Si-Wei Chen, Xue-Song Wang, Shun-Ping Xiao, and Sato, Motoyuki
- Subjects
SYNTHETIC aperture radar ,POLARIMETRIC remote sensing ,DECOMPOSITION method ,LEAST squares ,REMOTE sensing - Abstract
Orientation angle compensation was incorporated into model-based decomposition to cure overestimation of the volume scattering contribution for interpretation of polarimetric synthetic aperture radar (PolSAR) data. The compensation is based on rotating the coherency matrix to minimize the cross-polarization term. However, this processing cannot always guarantee that the double- and odd-bounce scattering components will be rotated back to zero orientation angle and left with zero cross-polarization power. As a result, built-up patches with large orientation angles may still suffer from the scattering mechanism ambiguity. In this paper, double- and odd-bounce scattering models were generalized to fit the cross-polarization and off-diagonal terms, by separating their independent orientation angles. A general decomposition framework is proposed that utilizes all elements of a coherency matrix. The residual minimization criterion is used for model inversion. All the model parameters are simultaneously obtained using a nonlinear least squares optimization technique. The manual intervention, branch conditions, and negative power issues are avoided. The performance and advantages of this approach are demonstrated and evaluated with spaceborne L-band ALOS/PALSAR and airborne X-band Pi-SAR PolSAR data sets. Comparison studies are also carried out and demonstrate that further improved decomposition performance is achieved by the proposed method, especially in oriented built-up areas. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
8. Adaptive Model-Based Polarimetric Decomposition Using PolInSAR Coherence.
- Author
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Si-Wei Chen, Xue-Song Wang, Yong-Zhen Li, and Sato, Motoyuki
- Subjects
INTERFEROMETRY ,ALGORITHM research ,NATURAL disasters ,EIGENVALUES ,POLARIZATION (Nuclear physics) ,SCATTERING (Physics) - Abstract
The overestimation of volume scattering power and the scattering mechanism ambiguity are still present in model-based decompositions even with the implementation of the deorientation processing. These effects are demonstrated and investigated. One possible reason is because of the limited dynamic range of the models themselves that are not fully satisfied for the mixed scene cases. An empirical volume scattering model is proposed, using the repeat-pass polarimetric synthetic aperture radar interferometry (PolInSAR) coherence, to extend the model dynamic range to be more adaptive. PolInSAR coherence is sensitive to different types of forests and terrains. The proposed model inherits these characteristics. In addition, it considers the cross-polarization power induced by oriented man-made structures. Thereby, a model-based polarimetric decomposition scheme is developed. The efficiency of the proposed method is demonstrated using E-SAR airborne and ALOS/PALSAR spaceborne repeat-pass PolInSAR datasets. Comparative experiments are carried out and show that the proposed decomposition overcomes the scattering mechanism ambiguity between forests and oriented built-up areas, since it successfully identifies the oriented buildings as double- or odd-bounce man-made structures while keeping the volume scattering dominant for the forests. Besides, the stable decomposition performance over the oriented built-up patches with quite different orientation angles also validates the improvement of the proposed decomposition. In addition, the demonstrations with short and long temporal baselines validate the generality of the proposed method. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
9. Disaster debris estimation using high-resolution polarimetric stereo-SAR.
- Author
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Koyama, Christian N., Gokon, Hideomi, Jimbo, Masaru, Koshimura, Shunichi, and Sato, Motoyuki
- Subjects
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EMERGENCY management , *MARINE debris , *OPTICAL resolution , *POLARIMETRIC remote sensing , *EARTHQUAKES , *OPTICAL images , *SYNTHETIC aperture radar - Abstract
This paper addresses the problem of debris estimation which is one of the most important initial challenges in the wake of a disaster like the Great East Japan Earthquake and Tsunami. Reasonable estimates of the debris have to be made available to decision makers as quickly as possible. Current approaches to obtain this information are far from being optimal as they usually rely on manual interpretation of optical imagery. We have developed a novel approach for the estimation of tsunami debris pile heights and volumes for improved emergency response. The method is based on a stereo-synthetic aperture radar (stereo-SAR) approach for very high-resolution polarimetric SAR. An advanced gradient-based optical-flow estimation technique is applied for optimal image coregistration of the low-coherence non-interferometric data resulting from the illumination from opposite directions and in different polarizations. By applying model based decomposition of the coherency matrix, only the odd bounce scattering contributions are used to optimize echo time computation. The method exclusively considers the relative height differences from the top of the piles to their base to achieve a very fine resolution in height estimation. To define the base, a reference point on non-debris-covered ground surface is located adjacent to the debris pile targets by exploiting the polarimetric scattering information. The proposed technique is validated using in situ data of real tsunami debris taken on a temporary debris management site in the tsunami affected area near Sendai city, Japan. The estimated height error is smaller than 0.6 m RMSE. The good quality of derived pile heights allows for a voxel-based estimation of debris volumes with a RMSE of 1099 m 3 . Advantages of the proposed method are fast computation time, and robust height and volume estimation of debris piles without the need for pre-event data or auxiliary information like DEM, topographic maps or GCPs. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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