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- 摘要
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Experimental Validation of Compact Tomosar for Vegetation Characterization
摘要： The study aims to explore the potentials of compact TomoSAR for vegetation characterization. The compact mode transmits either in linear or circular polarized waves and receives at horizontal and vertical polarization providing a different perspective to the understanding of the target. The goal of this study is to assess and evaluate the performance of compact polarimetric SAR modes to reconstruct the 3D reflectivity of forest volume and estimate the vertical structure in comparison with FP modes. Preliminary investigation of compact TomoSAR is conducted using L-band BIOSAR 2008 dataset consisting of six flight tracks acquired over Krycklan in northern Sweden.
关键词： SAR Tomography,Reflectivity,Vegetation Structure,Compact Polarimetry,PolInSAR
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Sea Oil Seep Monitoring Using A Time Series of Co-Polarized Coherent Sar Measurements
摘要： In this study, coherent co–polarized synthetic aperture radar (SAR) information is exploited for sea oil seep monitoring purposes. A time series of 33 TerraSAR-X StripMap SAR data, collected over a well–known oil seep in Gulf of Mexico, is exploited to analyze the influence of incidence angle and wind conditions on the co–polarized phase difference (CPD). Furthermore, the benefits of using phase information for oil seep observation are assessed. Experimental results show that: i) incidence angle has a remarkable effect in broadening/shrinking the CPD statistical distribution and, ii) the CPD provides spatial information on the oil seep damping properties.
关键词： polarimetry,co–polarized phase difference,synthetic aperture radar,oil seep
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Calibration Challenges for the Biomass P-Band SAR Instrument
摘要： The BIOMASS mission gives completely new challenges in external calibration arising from the orbital pattern needed for the tomographic and Pol-InSAR phases of the mission, the strong effects of the ionosphere at P-band, and the lack of pre-existing P-band data except over very limited parts of the globe. Together these create problems that can only be solved by combining infrequent visits to instrumented calibration sites with systematic exploitation of the properties of distributed targets and targets of opportunity. Proposed approaches to performing radiometric and polarimetric calibration are described, together with meeting geolocation accuracy requirements.
关键词： calibration,Radiometry,ionospheric correction,geolocation,polarimetry
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Long- Term P-Band Tomosar Observations from the Borealscat Tower Experiment
摘要： SAR tomography at P-band allows the separation of scatterers throughout the vertical extent of a forest canopy, offering a SAR observable that can be used for biomass estimation. But the vertical backscattering distribution of forests are sensitive to changes in the weather and seasons, effects which are poorly understood. In this study, a tower-based radar is used to produce fully-polarimetric tomographic images of a boreal forest at P-band which are analysed over a period of one year. The largest variations seen were due to sub-zero temperatures, causing a drop in the effective scattering height. Seasonal changes in soil moisture and temperature caused a drop in ground-level backscatter at HH-polarisation and a drop in canopy-level cross-polarised backscatter during the summer.
关键词： boreal forest,long time series,ground-based radar,SAR tomography,polarimetry,BIOMASS
更新于2025-09-09 09:28:46
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The Imaging X-ray Polarimetry Explorer (IXPE)
摘要： Recently selected by NASA as the next SMall EXplorer (SMEX) mission for a launch in 2021, the Imaging X-ray Polarimetry Explorer (IXPE) marks the renaissance of X-ray polarimetry, with the prospect of measuring linear polarization from tens of astronomical X-ray sources. IXPE will expand the X-ray view of the Universe by providing new and unique insight into our understanding of some of the most violent celestial objects, such as stellar and supermassive black holes and neutron stars. In this contribution we shall discuss the scientific prospects of the mission, as well as the status of the program, with particular emphasis on the development of the focal plane detectors sensitive to polarization.
关键词： Imaging,Micro-pattern gas detectors,GEM,X-ray,Polarimetry
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Comparison of Gaofen-3 and Radarsat-2 Data for Polarimetric Sar Image Classification
摘要： On 10 August 2016 China launched the GF-3, its first C-band polarimetric synthetic aperture radar (SAR) satellite, which was put into operation at the end of January, 2017. The GF-3 polarimetric SAR has many advantages such as high resolution and multi-polarization imaging capabilities. Polarimetric SAR can fully characterize the backscatter property of targets, and thus it is of great interest to explore the physical scattering mechanisms of terrain types, which is very important in interpreting polarimetric SAR imagery and for its further usages in Earth observation. Both Radarsat-2 and Gaofen-3 satellites operate in C-band and are designed for similar missions. In this study, we compare the performances of fully polarimetric Gaofen-3 and Radarsat-2 data in representation of terrain types. By using several classic polarimetric features and the iterative Wishart-distribution based classifier, Gaofen-3 and Radarsat-2 data are compared in the aspects of polarimetric property preservation and capability of terrain classification.
关键词： terrain classification,polarimetric features,Radarsat-2,radar polarimetry,Gaofen-3
更新于2025-09-09 09:28:46
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Ellipsometry - Principles and Techniques for Materials Characterization || Photoelastic Modulated Imaging Ellipsometry
摘要： Photoelastic modulator (PEM)-based ellipsometry employed either lock-in amplifiers or the Fourier analysis technique to obtain the ellipsometric parameters almost in real-time that makes the system with a feature of fast measurement speed, higher stability, and sensitivity at small retardations. Since the PEM modulation frequency is too high to compare it with the exposure time of the camera, photoelastic modulator–based approach is not applicable for a two-dimensional ellipsometric measurement. Here, we represent a novel technique that coordinates with the light pulses and PEM modulation that can freeze the time-varied signals. Thus, two-dimensional ellipsometric parameters can be obtained within few seconds. In addition to ellipsometric measurement, this approach also can be extended to other imaging polarimetry measurements, such as Stokes parameters and Mueller matrix. Moreover, since the chromatic dispersion of birefringence was also a significant issue in the polarization modulation systems, we proposed an equivalent phase retardation technique to deal with this issue. This technique was confirmed by a dual wavelength measurement result without changing the optical configuration of the system. The concept and the theory of this system were indicated in the preceding section, and the passage below described some calibration issues for the photoelastic modulator. Some measurement results were revealed in the final part of this chapter.
关键词： imaging polarimetry,photoelastic modulator,Stokes parameter,dual wavelength,Mueller matrix,ellipsometric parameters
更新于2025-09-09 09:28:46
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A New Target Detector Based on Subspace Projections Using Polarimetric SAR Data
摘要： Most applications of radar imagery require processing techniques which achieve one fundamental goal: characterize and detect the constituent scatterers for each pixel in the scene. In this paper, we take a new look at the target detection issue in polarimetric synthetic aperture radar data and assume several canonical scattering mechanisms as our signal sources whose combination of them with appropriate weight fractions formed the scattering vector of each pixel. The presence of speckle as a consequence of coherent processing of the scattered signals is modeled as signal-dependent additive noise. The set of the scattering mechanisms is divided into two groups: objected scattering mechanism belonging to the target, and nonobjected scattering mechanisms. Then, we make use of two techniques based on subspace projections for speckle reduction and the nonobjected scattering mechanisms annihilation, followed by detecting the presence of the scattering mechanism of interest. In the problem formulation scenario, a novel feature space is proposed consisting of two subspaces—the objected subspace and the nonobjected subspace. Then, the detection approach under this scenario is derived. An orthogonal subspace projection technique is utilized for speckle reduction. Moreover, in order to annihilate the nonobjected subspace, each pixel’s feature vector is obliquely projected onto the objected subspace. With the annihilation of the nonobjected subspace and using the polarimetric information of the objected subspace, the detectability of the target scattering mechanism is therefore enhanced. Finally, evaluation against C-, L-, and P-band fully polarimetric SAR data sets is provided with a significant agreement with the expected results.
关键词： synthetic aperture radar (SAR),subspace projection,Polarimetry,target detection,scattering vector
更新于2025-09-09 09:28:46
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Polarimetry of Water Ice Particles Providing Insights on Grain Size and Degree of Sintering on Icy Planetary Surfaces
摘要： The polarimetry of the light scattered by planetary surfaces is a powerful tool to provide constraints on their microstructure. To improve the interpretation of polarimetric data from icy surfaces, we have developed the POLarimeter for ICE Samples complementing the measurement facilities of the Ice Laboratory at the University of Bern. The new setup uses a high precision Stokes polarimeter to measure the degree of polarization in the visible light scattered by surfaces at moderate phase angles (from 1.5° to 30°). We present the photometric and polarimetric phase curves measured on various surfaces made of pure water ice particles having well-controlled size and shape (spherical, crushed, and frost). The results show how the amplitude and the shape of the negative polarization branch change with the particles sizes and the degree of metamorphism of the ice. We found that fresh frost formed by water condensation on cold surfaces has a phase curve characterized by resonances (Mie oscillations) indicating that frost embryos are transparent micrometer-sized particles with a narrow size distribution and spherical shape. Comparisons of these measurements with polarimetric observations of the icy satellites of the Solar System suggest that Europa is possibly covered by relatively coarser (~40–400 μm) and more sintered grains than Enceladus and Rhea, more likely covered by frost-like particles of few micrometers in average. The great sensitivity of polarization to grain size and degree of sintering makes it an ideal tool to detect hints of ongoing processes on icy planetary surfaces, such as cryovolcanism.
关键词： sintering,icy planetary surfaces,grain size,polarimetry,water ice particles
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Flood-Area Detection Using Palsar-2 Data for Heavy Rainfall Disasters in Japan
摘要： Rapid and all-weather detection of flood areas is needed for monitoring and mitigating flood disasters. In this paper, we investigated flood area detection using ALOS-2 PALSAR-2 data acquired during the 2015 heavy rainfall disaster in the Kanto and Tohoku areas, Japan. We detected flood areas by thresholding amplitude images from PALSAR-2 and then evaluated their accuracies against inundation maps based on aerial photographs. The highest accuracy was a 0.583 kappa coefficient in flood/non-flood discrimination. Our comparative study results indicate that lower off-nadir angles (around 30 degrees or less) are effective in the detection of flood areas. We also found polarimetric analysis and speckle filtering to be effective in improving accuracy. The results of this study demonstrate the feasibility of using PALSAR-2 data for rapid flood monitoring and as a reference for future flood disasters.
关键词： radar polarimetry,disaster monitoring,image processing,ALOS-2,synthetic aperture radar
更新于2025-09-09 09:28:46