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Applying iterative method to solving high-order terms of seafloor topography / Diao Fan in Marine geodesy, Vol 43 n° 1 (janvier 2020)  

Public [article]  inMarine geodesy > Vol 43 n° 1 (janvier 2020) . - pp 63 - 85 Titre : Applying iterative method to solving high-order terms of seafloor topography Type de document : Article/Communication Auteurs : Diao Fan, Auteur ; Shanshan Li, Auteur ; Shuyu Meng, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 63 - 85 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie [Termes descripteurs IGN] Chine, mer de [Termes descripteurs IGN] fond marin [Termes descripteurs IGN] force de gravitation [Termes descripteurs IGN] gravimétrie en mer [Termes descripteurs IGN] inversion [Termes descripteurs IGN] itération [Termes descripteurs IGN] relief sous-marin Résumé : (auteur) We introduce an iterative inversion method to address the problems in high-order seafloor topography inversion using gravity data (gravity anomaly and vertical gravity gradient anomaly), such as the difficulty in computing the equation and the uniqueness of the calculation results. A part of the South China Sea is selected as the experimental area. Considering the coherence and admittance function of gravity topography and vertical gravity gradient topography, the inversion band of the gravity anomaly and vertical gravity gradient anomaly in the study area is 30 km–120 km. Seafloor topography models of different orders are constructed using an iterative method, and the performance of each seafloor topography model is analyzed against ETOPO1 and other seafloor topography models. The experimental results show that as the inversion order increases, the clarity and richness of seafloor topographic expression continuously improve. However, the accuracy of seafloor topography inversion does not improve significantly when the inversion order exceeds a certain value, which is related to the contribution of high-order seafloor topography to gravity information. The results show that the accuracy of BGT4 (inversion model constructed by the gravity anomaly) is slightly poorer than that of BVGGT4 (inversion model constructed by the vertical gravity gradient anomaly) in areas with complex topography, such as multi-seamounts and trenches, and the results are generally better in areas with flat seafloor topography. Numéro de notice : A2020-463 Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2019.1670298 date de publication en ligne : 08/10/2019 En ligne : https://doi.org/10.1080/01490419.2019.1670298 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95125 [article]

Robust object-based multipass InSAR deformation reconstruction / Jian Kang in IEEE Transactions on geoscience and remote sensing, vol 55 n° 8 (August 2017)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 55 n° 8 (August 2017) . - pp 4239 - 4251 Titre : Robust object-based multipass InSAR deformation reconstruction Type de document : Article/Communication Auteurs : Jian Kang, Auteur ; Yuanyuan Wang, Auteur ; Marco Körner, Auteur ; Xiao Xiang Zhu, Auteur Année de publication : 2017 Article en page(s) : pp 4239 - 4251 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] classification orientée objet [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] interféromètrie par radar à antenne synthétique [Termes descripteurs IGN] inversion [Termes descripteurs IGN] pont [Termes descripteurs IGN] surveillance géologique [Termes descripteurs IGN] tenseur Résumé : (Auteur) Deformation monitoring by multipass synthetic aperture radar (SAR) interferometry (InSAR) is, so far, the only imaging-based method to assess millimeter-level deformation over large areas from space. Past research mostly focused on the optimal retrieval of deformation parameters on the basis of a single pixel or a pixel cluster. Only until recently, the first demonstration of object-based urban infrastructure monitoring by fusing InSAR and the semantic classification labels derived from optical images was presented by Wang et al. Given such classification labels in the SAR image, we propose a general framework for object-based InSAR parameter retrieval, where the parameters of the whole object are jointly estimated by the inversion of a regularized tensor model instead of pixelwise. Our approach does not assume the stationarity of each sample in the object, which is usually assumed in other pixel cluster-based methods, such as SqueeSAR. In addition, to handle outliers in real data, a robust phase recovery step prior to parameter retrieval is also introduced. In typical settings, the proposed method outperforms the current pixelwise estimators, e.g., periodogram, by a factor of several tens in the accuracy of the linear deformation estimates. Last but not least, for a practical demonstration on bridge monitoring, we present a full workflow of long-term bridge monitoring using the proposed approach. Numéro de notice : A2017-492 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2017.2684424 En ligne : http://dx.doi.org/10.1109/TGRS.2017.2684424 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86422 [article]

Ionosphere probing with simultaneous GNSS radio occultations / Viet-Cuong Pham in GPS solutions, vol 21 n° 1 (January 2017)  

Public [article]  inGPS solutions > vol 21 n° 1 (January 2017) . - pp 101 - 109 Titre : Ionosphere probing with simultaneous GNSS radio occultations Type de document : Article/Communication Auteurs : Viet-Cuong Pham, Auteur ; Jyh-Ching Juang, Auteur Année de publication : 2017 Article en page(s) : pp 101 - 109 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] gradient d'ionosphère [Termes descripteurs IGN] inversion [Termes descripteurs IGN] occultation du signal [Termes descripteurs IGN] orbite basse [Termes descripteurs IGN] régularisation de Tychonoff [Termes descripteurs IGN] teneur totale en électrons Résumé : (Auteur) Radio occultation (RO) is a powerful technique for providing vertical profiles of refractivity, temperature, pressure, and water vapor of the neutral atmosphere and electron density of the ionosphere. The Abel inversion method which is based on the spherical symmetry assumption has been widely utilized to retrieve electron density profiles (EDPs) from RO measurements, which are available by observing Global Navigation Satellite System (GNSS) satellites from low-earth-orbit satellites. It is well known that the Abel inversion is subject to errors in the presence of ionospheric horizontal gradients. With the arrival of new navigation systems, the opportunities of establishing simultaneous GNSS RO events are increasing. We develop an improved Abel inversion technique that accounts for pairs of simultaneous RO events to relax the spherical symmetry assumption. Through the use of Tikhonov regularization, the problem is formulated so that numerical conditioning is improved and a priori information such as expected electron density, asymmetric factor, and vertical total electron content can be incorporated. Appropriate weighting can be determined to reflect the availability and quality of information. By balancing the reference data and measurements, the method thus paves a way for ionospheric probing in challenging geomagnetic conditions as both the EDP at the intersection and the horizontal gradients are retrieved. Simulation and experimental results are provided to show the effectiveness of the proposed method. The robustness and sensitivity of the proposed method are also assessed. Numéro de notice : A2017-014 Thématique : POSITIONNEMENT Nature : Article En ligne : http://dx.doi./org/10.1007/s10291-015-0501-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83936 [article]

Forest height estimation by means of Pol-InSAR data inversion : The role of the vertical wavenumber / Florian Kugler in IEEE Transactions on geoscience and remote sensing, vol 53 n° 10 (October 2015)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 10 (October 2015) . - pp 5294 - 5311 Titre : Forest height estimation by means of Pol-InSAR data inversion : The role of the vertical wavenumber Type de document : Article/Communication Auteurs : Florian Kugler, Auteur ; Seung-Kuk Lee, Auteur ; Irena Hajnsek, Auteur ; Konstantinos P. Papathanassiou, Auteur Année de publication : 2015 Article en page(s) : pp 5294 - 5311 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] données polarimétriques [Termes descripteurs IGN] estimation statistique [Termes descripteurs IGN] forêt [Termes descripteurs IGN] hauteur des arbres [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] interféromètrie par radar à antenne synthétique [Termes descripteurs IGN] inversion [Termes descripteurs IGN] Pol-INSAR [Termes descripteurs IGN] polarimétrie radar [Termes descripteurs IGN] validation des données Résumé : (Auteur) This paper examines the multifaceted effect of the effective spatial baseline, as expressed through the vertical (interferometric) wavenumber, on the inversion of forest height from polarimetric interferometric synthetic aperture radar (Pol-InSAR) data. First, the role of the vertical wavenumber in relating forest height to the interferometric (volume) coherence is introduced. Through the review of the forest height inversion from Pol-InSAR data, the effect of the vertical wavenumber on the inversion performance is evaluated. The selection of optimum with respect to forest height inversion performance, vertical wavenumbers is discussed. The impact of the acquisition geometry and terrain slopes on the vertical wavenumber and their consideration in the inversion methodology is addressed. The individual effects discussed are demonstrated by means of airborne repeat pass Pol-InSAR acquisitions in L- and P-band acquired over different forest conditions, including a boreal, a temperate, and a tropical forest test site. The achieved forest height inversion performance is validated against reference height data derived from airborne LIDAR acquisitions. Numéro de notice : A2015-747 Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2420996 date de publication en ligne : 04/05/2015 En ligne : https://doi.org/10.1109/TGRS.2015.2420996 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78755 [article]

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Unifying regularization and Bayesian estimation methods for enhanced imaging with remotely sensed data - part 2: implementation and performance issues / Y.V. Shkvarko in IEEE Transactions on geoscience and remote sensing, vol 42 n° 5 (May 2004)

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 42 n° 5 (May 2004) . - pp 932 - 940 Titre : Unifying regularization and Bayesian estimation methods for enhanced imaging with remotely sensed data - part 2: implementation and performance issues Type de document : Article/Communication Auteurs : Y.V. Shkvarko, Auteur Année de publication : 2004 Article en page(s) : pp 932 - 940 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes descripteurs IGN] entropie [Termes descripteurs IGN] équation non linéaire [Termes descripteurs IGN] estimation bayesienne [Termes descripteurs IGN] image ERS-SAR [Termes descripteurs IGN] implémentation (informatique) [Termes descripteurs IGN] inversion [Termes descripteurs IGN] méthode robuste Résumé : (Auteur) The fused Bayesian-regularization (FBR) method from a companion paper provides a rigorous theoretical formalism for optimal estimation of the power spatial spectrum pattern (SSP) of the wave field scattered from the probing surface as it is required for enhanced radar imaging of the remotely sensed scenes. Being nonlinear and solution-dependent, the optimal FBR method requires extremely complex nonlinear solution-dependent operator inversions and, therefore, cannot be recommended as a numerically realizable estimator of the SSP. Here, we design a family of robust easy-to-implement FBR algorithms, provide the relevant computational recipes, and discuss their performances. We comment on the practical aspects of the robustified FBR estimators, such as numerical implementation and improvement in the output SNR. The advantage in using the proposed robust FBR method is demonstrated through simulations of enhancing the SAR images formed using the conventional matched filtering of the trajectory signal. Numéro de notice : A2004-194 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26721 [article]

Voir aussi

• Unifying regularization and Bayesian estimation methods for enhanced imaging with remotely sensed data - part 1: theory / Y.V. Shkvarko in IEEE Transactions on geoscience and remote sensing, vol 42 n° 5 (May 2004)

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Approaches to fractional land cover and continuous field mapping: a comparative assessment over the BOREAS [BOReal Ecosystem Atmosphere Study] study region / R. Fernandes in Remote sensing of environment, vol 89 n° 2 (30/01/2004)

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Bidirectional NDVI and atmospherically resistant BRDF inversion for vegetation canopy / F. Gao in IEEE Transactions on geoscience and remote sensing, vol 40 n° 6 (June 2002)

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Etude de méthodes d'inversion des données du Tams (télémètre laser aéroporté à champ large) pour la surveillance des mouvements verticaux du sol / Luc Mathis (2002)

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Inversion des densités à l'intérieur du volume des sources sur un critère de minimisation d'énergie / Olivier Jamet (2002)

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Une approche du problème d'inversion des mesures d'un satellite géostationnaire en vue de l'estimation de l'albédo de surface / B. Pinty (1988)

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Utilisation possible de l'inversion tridimensionnelle, dans les problèmes de géophysique / H.M. Dufour (01/09/1984)

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Untersuchungen zur Lösung und Inversion schwach besetzter großer geodätischer Normalgleichungen / W. Stark (1984)

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Grands systèmes linéaires / Georges Balmino (1977)

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