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Polarimetric SAR calibration and residual error estimation when corner reflectors are unavailable / Lei Shi in IEEE Transactions on geoscience and remote sensing, vol 58 n° 6 (June 2020)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 58 n° 6 (June 2020) . - pp 4454 - 4471 Titre : Polarimetric SAR calibration and residual error estimation when corner reflectors are unavailable Type de document : Article/Communication Auteurs : Lei Shi, Auteur ; Pingxiang Li, Auteur ; Jie Yang, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 4454 - 4471 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] bruit (théorie du signal) [Termes descripteurs IGN] coin réflecteur [Termes descripteurs IGN] dégradation du signal [Termes descripteurs IGN] données polarimétriques [Termes descripteurs IGN] étalonnage [Termes descripteurs IGN] extraction automatique [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] interruption du signal [Termes descripteurs IGN] polarimétrie radar [Termes descripteurs IGN] polarisation croisée [Termes descripteurs IGN] rétrodiffusion de Bragg Résumé : (auteur) In this article, we propose a polarimetric calibration (PolCal) algorithm to estimate the system crosstalk, cross-polarization (x-pol), and co-polarization (co-pol) channel imbalance (CI) when ground corner reflectors (CRs) are unavailable. The current PolCal process requires at least one trihedral CR to determine the co-pol CI. However, the deployment of ground CRs is costly and may even be impossible in some areas. To calibrate a polarimetric image without CRs, our proposed method automatically extracts the volume-dominated and Bragg-like pixels as a reference to estimate the crosstalk, x-pol, and co-pol CI values. Then, a first-order polynomial model is exploited to fit the co-pol CI to further improve calibration accuracy. In the experimental section, we demonstrate the effectiveness of our proposed method with data from two of China’s newly developed very high-resolution systems. The experiments confirmed that the proposed workflow can be considered as a feasible calibration scheme when the ground deployment of CRs is impossible, and it is also an effective analysis tool for the assessment of calibrated products. Numéro de notice : A2020-286 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2020.2964732 date de publication en ligne : 20/01/2020 En ligne : https://doi.org/10.1109/TGRS.2020.2964732 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95109 [article]

Polarization dependence of azimuth cutoff from quad-pol SAR images / Huimin Li in IEEE Transactions on geoscience and remote sensing, vol 57 n° 12 (December 2019)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 57 n° 12 (December 2019) . - pp 9878 - 9887 Titre : Polarization dependence of azimuth cutoff from quad-pol SAR images Type de document : Article/Communication Auteurs : Huimin Li, Auteur ; Alexis Mouche, Auteur ; He Wang, Auteur ; Justin E. Stopa, Auteur ; Bertrand Chapron, Auteur Année de publication : 2019 Article en page(s) : pp 9878 - 9887 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] angle d'incidence [Termes descripteurs IGN] azimut [Termes descripteurs IGN] données polarimétriques [Termes descripteurs IGN] image Gaofen [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] image Radarsat [Termes descripteurs IGN] polarisation [Termes descripteurs IGN] polarisation croisée [Termes descripteurs IGN] surface de la mer [Termes descripteurs IGN] transformation non linéaire [Termes descripteurs IGN] vague Résumé : (auteur) Although basic understanding of the synthetic aperture radar (SAR) imaging mechanism of ocean waves has been achieved, challenges still remain. In this paper, a large number of quad-polarized SAR images are analyzed to help assess how the standard SAR imaging transformation applies to all polarization channels. Foremost, the azimuth cutoff, a parameter essentially governed by the detected wave motions, is today solely related to radar configuration and the ocean wave spectrum but not to the polarization configuration. As obtained, the analyses based on quad-polarized Radarsat-2 and Gaofen-3 products document the distinct dependence of azimuth cutoff on polarization and incidence angle. Especially for cross-polarized VH measurements, azimuth cutoff estimates are generally larger than copolarized HH ones, the latter already being larger than values estimated under VV configuration. This trend increases with the incidence angle. The systematic comparisons between SAR measurements and simulations further demonstrate that the present SAR nonlinear transformation may not properly take into account the differing coherence time associated with the multi-polarized observation of ocean scenes. In particular, to reproduce the large azimuth cutoff parameters of cross-polarized images, a reduced coherence time shall be expected. This measurable sensitivity shall enhance the capabilities of polarized SAR systems to precisely derive more ocean surface properties, especially the influence of wave breakers, by combining both the copolarization and cross-polarization measurements. Numéro de notice : A2019-601 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2019.2929835 date de publication en ligne : 14/08/2019 En ligne : http://doi.org/10.1109/TGRS.2019.2929835 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94602 [article]

Global observations of ocean surface winds and waves using spaceborne synthetic aperture radar measurements / Huimin Li (2019)  

Public Titre : Global observations of ocean surface winds and waves using spaceborne synthetic aperture radar measurements Type de document : Thèse/HDR Auteurs : Huimin Li, Auteur Editeur : Institut Mines-Télécom Atlantique - IMT Année de publication : 2019 Importance : 163 p. Format : 21 x 30 cm Note générale : Bibliographie Thèse de Doctorat de l'Ecole Nationale Supérieure des Mines-Telecom Atlantique Bretagne Pays de la Loire-IMT Atlantique Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] angle d'incidence [Termes descripteurs IGN] étalonnage des données [Termes descripteurs IGN] fonction de transfert de modulation [Termes descripteurs IGN] houle [Termes descripteurs IGN] image Envisat-ASAR [Termes descripteurs IGN] image Gaofen [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] image Radarsat [Termes descripteurs IGN] image Sentinel-SAR [Termes descripteurs IGN] océan [Termes descripteurs IGN] phénomène météorologique [Termes descripteurs IGN] polarisation croisée [Termes descripteurs IGN] radar à antenne synthétique [Termes descripteurs IGN] rapport signal sur bruit [Termes descripteurs IGN] tempête [Termes descripteurs IGN] trajectoire [Termes descripteurs IGN] vague [Termes descripteurs IGN] vent Index. décimale : THESE Thèses et HDR Résumé : (auteur) Spaceborne synthetic aperture radar (SAR) has been demonstrated invaluable in observing the global ocean winds and waves. SAR images acquired by multiple sensors are employed, including Sentinel-1(S-1), Envisat/ASAR, Gaofen-3 and Radarsat-2. This thesis reviews the commonly used SAR parameters (NRCS and azimuth cutoff) in the first part. A series of calibration steps are required to obtain a proper NRCS and assessment of NRCS is carried out for S-1wave mode (WV). It turns out that WV is poorly calibrated and is thus re-calibrated to obtain accurate NRCS. Azimuth cut off is demonstrated to be complementary to NRCS and can account for the sea state impact on the wind retrieval. Based on the available fully polarimetric SAR products, azimuth cut off is found to vary greatly with polarizations. The present SAR mapping transformation is sufficient to interpret the co-polarized azimuth cut off, while not for the cross-polarization. With the limitations of SAR imaging in mind, a new parameter is proposed and defined based on the SAR image cross-spectra, termed as MACS. The imaginary part of MACS is found to be a signed quantity relative to the wind direction. Given this dependence, an independent wind retrieval algorithm is expected to benefit. The magnitude of MACS is able to aid for estimate of modulation function of SAR mapping. In addition, MACS also gives promising results regarding the global wave studies. The global signatures of MACS at various wave lengths are well representative of the winds distributions, spatially and seasonally. MACS of long waves shows greater values over the storm tracks while the shorter waves are mostly within the trader winds. These results are expected to help evaluate the model outputs and complement further studies of the global wave spectral climate. Data continuity in the coming 10 years shall extend the study towards longer duration. Note de contenu : I- Background and study of the existing SAR parameters Chap. 1 - Background Chap. 2 - SAR imaging of the ocean surface Chap. 3 - Status and challenges in SAR winds Chap. 4 - Azimuth cutoff of polarimetric SAR images II- A new SAR parameter and its applications in wind/wave study Chap. 5 - A new SAR parameter: MACS and its directionality Chap. 6 - Statistics of MACS magnitude and derived RAR MTF Chap. 7 - Investigation of global ocean waves using SAR MACS Chap. 8 - Conclusion and perspectives Numéro de notice : 25729 Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : Sciences de la Mer et du littoral : Spécialité : Océanographie, Physique et Environnement : Plouzané: 2019 Organisme de stage : Ifremer En ligne : https://tel.archives-ouvertes.fr/tel-02164506 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94895

Polarization orientation angle and polarimetric SAR scattering characteristics of steep terrain / Jong-Sen Lee in IEEE Transactions on geoscience and remote sensing, vol 56 n° 12 (December 2018)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 56 n° 12 (December 2018) . - pp 7272 - 7281 Titre : Polarization orientation angle and polarimetric SAR scattering characteristics of steep terrain Type de document : Article/Communication Auteurs : Jong-Sen Lee, Auteur ; Thomas L. Ainsworth, Auteur ; Yanting Wang, Auteur Année de publication : 2018 Article en page(s) : pp 7272 - 7281 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] angle de visée [Termes descripteurs IGN] bande C [Termes descripteurs IGN] bande L [Termes descripteurs IGN] constante diélectrique [Termes descripteurs IGN] données polarimétriques [Termes descripteurs IGN] escarpement [Termes descripteurs IGN] humidité du sol [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] image TOPSAR [Termes descripteurs IGN] modèle de diffusion du rayonnement [Termes descripteurs IGN] montagne [Termes descripteurs IGN] pente [Termes descripteurs IGN] polarimétrie radar [Termes descripteurs IGN] polarisation croisée [Termes descripteurs IGN] réflectance spectrale [Termes descripteurs IGN] rétrodiffusion de Bragg [Termes descripteurs IGN] teneur en eau de la végétation Résumé : (auteur) Polarization orientation angle (POA) is an important parameter of polarimetric radar scattering from slopes in mountainous region. It is known that surface tilted in azimuth direction and buildings not aligned in the along-track direction induce polarization orientation shifts. Earlier research has established orientation angle as a function of radar imaging geometry and surface slopes, and that POA estimation can be derived from polarimetric radar data using circular polarization. Besides these, polarimetric scattering from steep slopes and its relation to POA remain not well understood. In this paper, we address these issues by adopting a tilted surface model based on Bragg scattering. We have found that, as the azimuthal slope increases, |VV| decreases at a faster rate than |HH|, they become equal, when POA is ±45°, and |HH| > |VV| afterward. In other words, the Pauli component, |HH-VV| reduced to zero at POA = ± 45°, and the typical Bragg scattering characteristics of |VV| > |HH| does not apply when steep slope is present inducing |POA| > 45°. Furthermore, the cross-pol |HV| does not always increase with azimuth slope but also reaches a maximum then decreases to zero. In addition, we investigate the effect of soil moisture on polarimetric SAR (PolSAR) scattering characteristics of steep terrain and the effect of vegetation over surface on POA estimation. The latter is demonstrated with NASA/JPL TOPSAR L-band PolSAR data and C-band InSAR data. Another significance of this paper is that it provides a direct and rigorous derivation of POA equations. The earlier version was derived from a different concept. Numéro de notice : A2018-557 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2018.2849931 date de publication en ligne : 01/08/2018 En ligne : http://dx.doi.org/10.1109/TGRS.2018.2849931 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91662 [article]

Relating statistical characteristics of cross-polarized phase difference to speckle noise / Huimin Li in Journal of applied remote sensing [en ligne], vol 9 (2015)  

Public [article]  inJournal of applied remote sensing [en ligne] > vol 9 (2015) . - 8 p. Titre : Relating statistical characteristics of cross-polarized phase difference to speckle noise Type de document : Article/Communication Auteurs : Huimin Li, Auteur ; Yunhua Wang, Auteur Année de publication : 2015 Article en page(s) : 8 p. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] données polarimétriques [Termes descripteurs IGN] filtrage du bruit [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] matrice de covariance [Termes descripteurs IGN] phase [Termes descripteurs IGN] polarimétrie radar [Termes descripteurs IGN] polarisation croisée Résumé : (auteur) A qualitative relationship between the statistical behavior of cross-polarized phase difference ϕhvvh and dominant noise type is examined based on the polarimetric noise model proposed. The noise model focusing on the covariance matrix is able to separate the multiplicative noise which only affects the amplitude from the additive noise that alters both the amplitude and phase. In the case of low noise, the phase is not affected by the noise and ϕhvvh distribution is predicted to be centered at 0 deg in terms of reciprocity theorem. The case of strong noise is much more complicated as the dominant noise type plays an important role in the statistics of ϕhvvh. The phase over the area where multiplicative noise dominates is not altered, thus the ϕhvvh distribution is expected to have similar behaviors to the case of low noise. However, the dominant additive noise would significantly affect the phase so that an obvious deviation from 0 deg for ϕhvvh distribution is expected. Experiments with Radarsat-2 full polarimetric imageries further validate this qualitative relationship. Numéro de notice : A2015-101 Thématique : IMAGERIE Nature : Article En ligne : http://remotesensing.spiedigitallibrary.org/article.aspx?articleid=2091528 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75392 [article]

Forest biomass estimation using texture measurements of high-resolution dual-polarization C-band SAR data / Latifur Rahman Sarker in IEEE Transactions on geoscience and remote sensing, vol 51 n° 6 Tome 1 (June 2013)  

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Improvement of stepped-frequency continuous wave Ground-Penetrating Radar cross-range resolution / I. Nicolaescu in IEEE Transactions on geoscience and remote sensing, vol 51 n° 1 Tome 1 (January 2013)  

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The TropiSAR airborne campaign in French Guiana : objectives, description, and observed temporal behavior of the backscatter signal / P. Dubois-Fernandez in IEEE Transactions on geoscience and remote sensing, vol 50 n° 8 (August 2012)  

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Characterization of Arctic sea ice thickness using high-resolution spaceborne polarimetric SAR data / J.W. Kim in IEEE Transactions on geoscience and remote sensing, vol 50 n° 1 (January 2012)  

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Classification comparisons between dual-pol, compact polarimetric and quad-pol SAR imagery / T. Ainsworth in ISPRS Journal of photogrammetry and remote sensing, vol 64 n° 5 (September - October 2009)

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