- 标题
- 摘要
- 关键词
- 实验方案
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A Reflection Symmetry Approximation of Multilook Polarimetric SAR Data and its Application to Freeman-Durden Decomposition
摘要： Freeman–Durden decomposition is a frequently used technique to analyze the scattering characteristics of multilook Polarimetric Synthetic Aperture Radar (POLSAR) data. When it is applied to the real POLSAR data, two problems emerge, namely, the volume scattering overestimation and negative powers. Many researchers think these two problems are caused by the insufficient decomposition algorithm, and the improved decomposition algorithms become more and more complicated, and some new problems such as the decomposed component is not model based also emerge. In this paper, we try to solve the two problems through another way. We think they are caused not by the insufficient decomposition algorithm but by the dogmatic input. Freeman–Durden decomposition explicitly assumes reflection symmetry. Its input is a direct truncation of the measured coherency matrix. The truncation can be regarded as a reflection symmetry approximation (RSA) of the measured coherency matrix. We first show some reasons why we do not think the truncation is a good RSA. Then, a new RSA is proposed based on the sum of three reflection symmetry components derived from the measured coherency matrix. Experimental results with several real POLSAR images show that, if the new RSA is used as the input of Freeman–Durden decomposition, the above-mentioned two problems no longer exist.
关键词： Polarimetric Synthetic Aperture Radar (POLSAR),radar polarimetry,Polarimetric decomposition
更新于2025-09-23 15:22:29
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A Sensitivity Analysis of the Standard Deviation of the Copolarized Phase Difference for Sea Oil Slick Observation
摘要： In this paper, a time series of 33 TerraSAR-X copolarized synthetic aperture radar (SAR) imagery collected in Stripmap mode over the Gulf of Mexico in a wide range of incidence angles and sea-state condition is exploited, together with a theoretical framework based on the X-Bragg scattering model, to analyze the effects of noise, angle of incidence, (AOI) and wind speed on the standard deviation of the copolarized phase difference (στc ) evaluated over sea surface with and without oil slicks. This large data set represents an unprecedented opportunity to analyze, for the ?rst time, the in?uence of both SAR acquisition and surface parameters on the broadening of the copolarized phase difference probability density function (pdf), (τc). Experimental results show that the X-Bragg scattering model, here adopted to predict the sea surface pτc (τc), gives an understanding of the increasing trend of στc with respect to AOI. It is shown that the noise signi?cantly contributes to broaden pτc (τc) over both slick-free and slick-covered sea surface, while the effects of low-to-moderate wind regimes are negligible. In addition, στc exhibits a larger sensitivity to the scene variability, if compared to single-polarization intensity channels, over both slick-free and oil-covered sea surface. This sensitivity is more pronounced at lower AOIs due to the higher noise equivalent sigma zero (NESZ) that affects larger AOIs.
关键词： Oceans,oil pollution,synthetic aperture radar,radar polarimetry
更新于2025-09-23 15:22:29
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Urban Tomographic Imaging Using Polarimetric SAR Data
摘要： In this paper, we investigate the potential of polarimetric Synthetic Aperture Radar (SAR) tomography (Pol-TomoSAR) in urban applications. TomoSAR exploits the amplitude and phase of the received data and offers the possibility to resolve multiple scatters lying in the same range–azimuth resolution cell. In urban environments, this issue is very important since layover causes multiple coherent scatterers to be mapped in the same range–azimuth image pixel. To achieve reliable and accurate results, TomoSAR requires a large number of multi-baseline acquisitions which, for satellite-borne SAR systems, are collected with long time intervals. Then, accurate tomographic reconstructions would require multiple scatterers to remain stable between all the acquisitions. In this paper, an extension of a generalized likelihood ratio test (GLRT)-based tomographic approach, denoted as Fast-Sup-GLRT, to the polarimetric data case is introduced, with the purpose of investigating if, in urban applications, the use of polarimetric channels allows for reduction of the number of baselines required to achieve a given scatterer’s detection performance. The results presented show that the use of dual polarization data allows the proposed detector to work in an equivalent or better way than use of a double number of independent single polarization channels.
关键词： generalized likelihood ratio test,synthetic aperture radar,sparse signals,polarimetry,radar detection,tomography
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on RFID Technology & Application (RFID-TA) - Macau, Macao (2018.9.26-2018.9.28)] 2018 IEEE International Conference on RFID Technology & Application (RFID-TA) - Research on Fast Algorithm for General Bistatic SAR Raw Signal
摘要： A fast algorithm for general bistatic synthetic aperture radar (SAR) raw signal based on two-dimensional frequency domain is proposed. The SAR echo signal model is established by the algorithm, the accurate expression of two-dimensional frequency domain for the bistatic SAR echo signal are deduced with series reversion. Simulating large range and azimuth coupling, the accurate computation of echo signal is realized and the complexity of the algorithm is analyzed. The simulation results show that the simulation speed of SAR echo is greatly improved under the premise of ensuring the high phase accuracy, and the validity of the algorithm is proved.
关键词： synthetic aperture radar (SAR),bistatic,series reversion,echo simulation
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Desnet: Deep Residual Networks for Descalloping of Scansar Images
摘要： Scalloping is one of the critical problems in ScanSAR images. It not only affects image visualization, but also influences the quantitative applications such as surface wind and wave retrievals in the ocean area. The existing method of descalloping needs artificial parameter setting and lacks generality in the image domain. A novel deep neural network based on residual learning for descalloping of ScanSAR images is proposed in this paper. The proposed method can eliminate scalloping patterns and has strong adaptive ability, which can handle inhomogeneous scalloping patterns and different scenarios. Experiments on GF-3 ScanSAR images verify the good performance of this method. The code for our models is available online.
关键词： synthetic aperture radar (SAR),deep neural network,scalloping patterns,ScanSAR,Residual learning
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Two-dimensional Spectrum for Diving Stage SAR Processing with High-order Equivalent Range Model
摘要： For airborne synthetic aperture radar (SAR) processing in its diving stage, the diving velocity brings additional range variance to the range history in the synthetic aperture time. The traditional hyperbolic range model is not accurate enough to approximate the actual range equation and the precise two-dimensional spectrum cannot be achieved. In order to address this problem, a highly accurate spectrum deduction based on high-order equivalent range model is proposed in this paper. By introducing the high-order terms, more degrees-of-freedom are obtained for the equivalent range model and the actual range history can be accurately fitted. Based on the achieved range model, the two-dimensional spectrum for diving stage SAR can be accessed. Simulation experiments are carried out to validate the effectiveness of proposed spectrum.
关键词： two-dimensional spectrum,diving stage,range model,Synthetic aperture radar (SAR)
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Effect of Non-Uniform Azimuth Sampling on Sar Image Formation Evaluated at 79Ghz
摘要： Conventional synthetic aperture radar (SAR) image formation requires uniform sampling along the azimuth direction. These image formation relies on frequency domain algorithms including the Range-Doppler Algorithm (RDA), Chirp-Scaling Algorithm (CSA) [1] etc, that make use of azimuth Fast Fourier Transform, hence the requirement of uniform sampling. While uniform sampling in space is not always achievable, the samples can be interpolated onto a uniform grid given the sampling rate is Nyquist. This paper studies the effect of SAR image formation when the azimuth sampling is not uniform, and not Nyquist in some interval. The results showed that even if there is a wide interval in the middle of the synthetic aperture with no samples, an image can still be formed. This result could be useful when the SAR antenna is a phased array, or when the hardware is generating bursts of pulses followed by a quiet window.
关键词： Image focusing,Back-Projection,Azimuth Sampling,Synthetic aperture radar
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Operational Agricultural Flood Monitoring with Sentinel-1 Synthetic Aperture Radar
摘要： Agricultural flood monitoring is important for food security and economic stability. Synthetic Aperture Radar (SAR) has the advantage over optical data by operating at wavelengths not impeded by cloud cover or a lack of illumination. This characteristic makes SAR a potential alternative to optical sensors for agricultural flood monitoring during disasters. The purpose of this study is to assess the effectiveness of using freely available Copernicus Sentinel-1 SAR data for operational agricultural flood monitoring in the United States (U.S.). The operational detection of flood inundation was tested during Hurricane Harvey in 2017, which resulted in significant flooding over Texas and Louisiana, U.S. This paper presents 1) the agricultural flood monitoring method that utilizes Sentinel-1 SAR, the NASS 2016 Cultivated Layer, and the NASS 2016 and 2017 Cropland Data Layers; 2) flood detection validation results and 3) inundated cropland and pasture acreage estimates. The study shows that Sentinel-1 SAR is an effective and valuable data source for operational disaster assessment of agriculture.
关键词： Hurricane Harvey,Flood Detection,Synthetic Aperture Radar,Agriculture Flood Monitoring,Sentinel-1
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Optronic High-Resolution SAR Processing with the Capability of Full-Resolution Imaging
摘要： The improvement of synthetic aperture radar (SAR) resolution brings a broader applications but poses a great burden for SAR data processor. Real-time processing becomes a difficulty. Optronic technology has been developed for SAR real-time processing due to its ultrafast processing speed. A novel real-time optronic high-resolution SAR processor is proposed in this paper. It has the capability of full-resolution imaging. Restricted with the data scale of spatial light modulators (SLMs), SAR raw data cannot be all encoded onto the light beams at a time. To solve this, subaperture architecture is introduced in our system scheme. SAR data is optically processed in parallel by multiple optical subaperture processing modules and synthesized into a full-resolution SAR image. The module is implemented by multiple SLMs and lenses, which is innovatively proposed in this paper. The proposed system is applicable to large-scale SAR data processing, and the data scale is easy to extend with implementation of adding identical optical subaperture processing modules. Airborne SAR real data is used in the experiment, and a high-resolution image is also given. The PSLR of the focus results with and without subaperture partition are analyzed, which validate the satisfying image quality of the proposed algorithm.
关键词： high resolution,synthetic aperture radar,spatial light modulator,subaperture,full-resolution imaging,Optronic processing
更新于2025-09-23 15:22:29
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Ratio-Based Multitemporal SAR Images Denoising: RABASAR
摘要： In this paper, we propose a fast and efficient multitemporal despeckling method. The key idea of the proposed approach is the use of the ratio image, provided by the ratio between an image and the temporal mean of the stack. This ratio image is easier to denoise than a single image thanks to its improved stationarity. Besides, temporally stable thin structures are well preserved thanks to the multitemporal mean. The proposed approach can be divided into three steps: 1) estimation of a 'superimage' by temporal averaging and possibly spatial denoising; 2) denoising of the ratio between the noisy image of interest and the 'superimage'; and 3) computation of the denoised image by remultiplying the denoised ratio by the 'superimage.' Because of the improved spatial stationarity of the ratio images, denoising these ratio images with a speckle-reduction method is more effective than denoising images from the original multitemporal stack. The amount of data that is jointly processed is also reduced compared to other methods through the use of the 'superimage' that sums up the temporal stack. The comparison with several state-of-the-art reference methods shows better results numerically (peak signal-noise-ratio and structure similarity index) as well as visually on simulated and synthetic aperture radar (SAR) time series. The proposed ratio-based denoising framework successfully extends single-image SAR denoising methods to time series by exploiting the persistence of many geometrical structures.
关键词： ratio image,speckle reduction,Multitemporal synthetic aperture radar (SAR) series,superimage
更新于2025-09-23 15:22:29