Co-polarization channel imbalance determination by the use of bare soil

Shi, Lei; Li, Pingxiang

doi:10.1016/j.isprsjprs.2014.06.007

Cited by 28 publications

(15 citation statements)

References 32 publications

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“…The comprehensive calibration and evaluation works of most common beams are planned in 2018. When the CRs could be found in scenes, user could consider exploit the nature media to approximately estimate system distortion elements (Van Zyl, 1990;Quegan, 1994;Ainsworth, 2006;Shi, 2014;Fore, 2015).…”

Section: Resultsmentioning

confidence: 99%

Preliminary Evaluation of Gaofen-3 Polarimetric and Radiometric Accuracy by Corner Reflectors in Inner Mongolia

Shi

Ding

et al. 2018

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:On August 10, 2016, China launched its first C-band full polarimetric radar satellite, named Gaofen-3 (GF-3), for urban and agriculture monitoring, landslide detection, ocean applications, etc. According to the design specification, GF-3 is expected to work at −35 dB crosstalk and 0.5 dB channel imbalance, with less than 10 degree error. The absolute radiometric bias is expected to be less than 1.5 dB in a single scene and 2.0 dB when operating for a long time. To complete the calibration and evaluation, the Institute of Electronics, Chinese Academy Sciences (IECAS) built a test site at Inner Mongolia, and deployed active reflectors (ARs) and trihedral corner reflectors (CRs) to solve and evaluate the hardware distortion. To the best of the authors' knowledge, the product accuracy of GF-3 has not been comprehensively evaluated in any open publication. The remote sensing community urgently requires a detailed report about the product accuracy and stability, before any subsequent application. From June to August of 2017, IECAS begun its second round ground campaign and deployed 10 CRs to evaluate product distortions. In this paper, we exploit Inner Mongolia CRs to investigate polarimetric and radiometric accuracy of QPSI I Stripmap. Although some CRs found fall into AR side lobe, the rest CRs enable us to preliminarily evaluate the accuracy of some special imaging beams. In the experimental part, the image of July 6, 2017 was checked by 5 trihedral CRs and the integration estimation method demonstrated the crosstalk varying from -42.65 to -32.74 dB, and the channel imbalance varying from -0.21 to 0.47 with phase error from -2.4 to 0.2 degree. Comparing with the theoretical radar cross-section of 1.235 m trihedral CR, i.e. 35 dB, the radiometric error varies about 0.20±0.29 dB in HH channel and 0.40±0.20 dB in VV channel.

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Section: Resultsmentioning

confidence: 99%

Preliminary Evaluation of Gaofen-3 Polarimetric and Radiometric Accuracy by Corner Reflectors in Inner Mongolia

Shi

Ding

et al. 2018

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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“…1(d), the P-band image is matched with the X-band mosaiced strip by a scale-invariant feature transform for the subsequent analysis (the code can be downloaded from http:// www.robots.ox.ac.uk/~vedaldi/code/sift.html, version 0.9.19). Although the nominal polarimetric calibration accuracy of the CASMSAR P-band is not public, we decided to recalibrate the Sinclair matrix and reduce the residual error by the use of the algorithms proposed in [10] and [11] Due to the processing principle of SAR, the collapse grade when only using the radar is usually no more than three levels, i.e., minor, moderate, and serious. In this letter, we generated the ground truth (GT) from two sources, i.e., by referring to the International Charter on Space and Major Disasters collapse map of Yushu [12] and by using the Major Natural Disasters Atlas 2010 of Yushu [13], which both contain the three collapse levels, i.e., minor, moderate, and serious.…”

Section: Data Set Description and Preprocessingmentioning

confidence: 99%

Building Collapse Assessment by the Use of Postearthquake Chinese VHR Airborne SAR

Shi

Sun

et al. 2015

IEEE Geosci. Remote Sensing Lett.

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In this letter, a comprehensive study of the mapping of building collapse levels by the use of postearthquake synthetic aperture radar (SAR) images is addressed. Although previous studies have successfully quantified the collapse level by the use of postevent SAR, the types of features that are of benefit to the final accuracy still remain unknown. This letter takes the Yushu earthquake as a case study to contribute in two key areas. First, the Chinese dual-band airborne SAR mapping system (CASMSAR), which collected very-high-resolution X-band and P-band images (0.50 and 1.1 m, respectively) by interferometric and polarimetric modes, is comprehensively evaluated for the first time. Second, to discriminate intact and fallen structures, multiconfiguration SAR data features are analyzed, including 40 polarimetric, 3 interferometric, and 138 texture features. Furthermore, a random-forest decision framework is introduced to quantify the importance score of each feature and to improve the discrimination accuracy. The CASMSAR experiment results indicate that the texture is recommended as a powerful input to quantify the extent of building collapse in Yushu.Index Terms-Building collapse, Chinese very high resolution (VHR) synthetic aperture radar (SAR), earthquake, postevent.

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“…The early PolCAL methods were designed using different kinds of corner reflectors (CRs) or polarimetric active radar calibrators (PARCs) [ 11 ]. Subsequently, some particular scattering targets such as bare soil, desert, and grassland have been investigated and taken as PolCAL references [ 12 , 13 , 14 ]. Rainforest has also been studied for PolCAL in some research [ 9 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Polarimetric Calibration and Quality Assessment of the GF-3 Satellite Images

Chang

Zhao

et al. 2018

Sensors

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Abstract:The GaoFen-3 (GF-3) satellite is the first fully polarimetric synthetic aperture radar (SAR) satellite designed for civil use in China. The satellite operates in the C-band and has 12 imaging modes for various applications. Three fully polarimetric SAR (PolSAR) imaging modes are provided with a resolution of up to 8 m. Although polarimetric calibration (PolCAL) of the SAR system is periodically undertaken, there is still some residual distortion in the images. In order to assess the polarimetric accuracy of this satellite and improve the image quality, we analyzed the polarimetric distortion errors and performed a PolCAL experiment based on scattering properties and corner reflectors. The experiment indicates that the GF-3 images can meet the satellite's polarimetric accuracy requirements, i.e., a channel imbalance of 0.5 dB in amplitude and ±10 degrees in phase and a crosstalk accuracy of −35 dB. However, some images still contain residual polarimetric distortion. The experiment also shows that the residual errors of the GF-3 standard images can be diminished after further PolCAL, with a channel imbalance of 0.26 dB in amplitude and ±0.2 degrees in phase and a crosstalk accuracy of −42 dB.

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Co-polarization channel imbalance determination by the use of bare soil

Cited by 28 publications

References 32 publications

Preliminary Evaluation of Gaofen-3 Polarimetric and Radiometric Accuracy by Corner Reflectors in Inner Mongolia

Preliminary Evaluation of Gaofen-3 Polarimetric and Radiometric Accuracy by Corner Reflectors in Inner Mongolia

Building Collapse Assessment by the Use of Postearthquake Chinese VHR Airborne SAR

Polarimetric Calibration and Quality Assessment of the GF-3 Satellite Images

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