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On the polarimetric variable improvement via alignment of subarray channels in PPAR using weather returns / Igor R. Ivić in IEEE Transactions on geoscience and remote sensing, Vol 59 n° 3 (March 2021)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > Vol 59 n° 3 (March 2021) . - pp 2015 - 2027 Titre : On the polarimetric variable improvement via alignment of subarray channels in PPAR using weather returns Type de document : Article/Communication Auteurs : Igor R. Ivić, Auteur Année de publication : 2021 Article en page(s) : pp 2015 - 2027 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] antenne radar [Termes IGN] coefficient de corrélation [Termes IGN] données météorologiques [Termes IGN] données polarimétriques [Termes IGN] écho radar [Termes IGN] faisceau [Termes IGN] mesurage de phase [Termes IGN] oscillateur [Termes IGN] polarimétrie radar [Termes IGN] variance de phase Résumé : (Auteur) Many modern phased-array radars (PARs) are multichannel systems that include multiple receivers for data acquisition. Each channel provides a signal from a group of Transmit/Receive modules comprising a section of the antenna. Channels typically consist of a full receive path, often with an independent local oscillator (LO) clock source. Such arrangement provides for beamforming flexibility on receive which can be applied in a digital domain. Consequently, the channel-to-channel phase and magnitude alignment is critical to maximizing the performance of the digital beamforming process and the accuracy of resulting detections and measurements. Herein, a novel method to improve such alignment using weather returns and achieve the improvement in the polarimetric variable estimates is described. Numéro de notice : A2021-213 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2020.3003293 Date de publication en ligne : 10/07/2020 En ligne : https://doi.org/10.1109/TGRS.2020.3003293 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97201 [article]

Improving operational radar rainfall estimates using profiler observations over complex terrain in Northern California / Haonan Chen in IEEE Transactions on geoscience and remote sensing, vol 58 n° 3 (March 2020)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 58 n° 3 (March 2020) . - pp 1821 - 1832 Titre : Improving operational radar rainfall estimates using profiler observations over complex terrain in Northern California Type de document : Article/Communication Auteurs : Haonan Chen, Auteur ; Robert Cifelli, Auteur ; Allen White, Auteur Année de publication : 2020 Article en page(s) : pp 1821 - 1832 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] Californie (Etats-Unis) [Termes IGN] correction d'image [Termes IGN] données radar [Termes IGN] erreur d'approximation [Termes IGN] faisceau [Termes IGN] montagne [Termes IGN] orographie [Termes IGN] précipitation [Termes IGN] prévision météorologique [Termes IGN] télédétection en hyperfréquence [Termes IGN] télédétection réflective [Termes IGN] visée verticale Résumé : (Auteur) Quantitative precipitation estimation (QPE) using operational weather radars in the western United States is still a challenging issue due to the beam blockage in the mountainous areas and complex rainfall microphysics induced by the orographic enhancement. This article aims to improve operational radar rainfall estimates in complex terrain by incorporating auxiliary remote sensing observations. An innovative vertical profile of reflectivity (VPR) correction scheme is developed for operational radar using observations from multiple vertically pointing profilers to represent the vertical structure of precipitation at various locations. A demonstration study in the Russian River basin in Northern California is detailed. Results show that the QPE performance is significantly improved after VPR correction, and this new VPR correction approach is superior to the conventional approach currently applied in the operational radar rainfall system. The normalized standard error of hourly rainfall estimates for the two precipitation events presented in this article is improved by ~20% after applying the proposed VPR correction scheme. Numéro de notice : A2020-090 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2019.2949214 Date de publication en ligne : 12/11/2019 En ligne : https://doi.org/10.1109/TGRS.2019.2949214 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94664 [article]

Bayesian iterative reconstruction methods for 3D X-ray Computed Tomography / Camille Chapdelaine (2019)  

Public Titre : Bayesian iterative reconstruction methods for 3D X-ray Computed Tomography Type de document : Thèse/HDR Auteurs : Camille Chapdelaine, Auteur ; Charles Soussen, Directeur de thèse Editeur : Paris-Orsay : Université de Paris 11 Paris-Sud Centre d'Orsay Année de publication : 2019 Importance : 185 p. Format : 21 x 30 cm Note générale : Bibliographie Thèse de Doctorat de l’Université Paris - Saclay préparée à l'Université Paris-Sud, Sciences et Technologies de l’Information et de la Communication (STIC), Traitement du signal et des images Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] artefact [Termes IGN] faisceau [Termes IGN] inférence [Termes IGN] itération [Termes IGN] processeur graphique [Termes IGN] rayon X [Termes IGN] reconstruction 3D [Termes IGN] reconstruction d'image [Termes IGN] segmentation [Termes IGN] spectroscopie [Termes IGN] théorème de Bayes [Termes IGN] tomographie [Termes IGN] volume (grandeur) Index. décimale : THESE Thèses et HDR Résumé : (auteur) In industry, 3D X-ray Computed Tomography aims at virtually imaging a volume in order to inspect its interior. The virtual volume is obtained thanks to a reconstruction algorithm based on projections of X-rays sent through the industrial part to inspect. In order to compensate uncertainties in the projections such as scattering or beam-hardening, which are cause of many artifacts in conventional filtered backprojection methods, iterative reconstruction methods bring further information by enforcing a prior model on the volume to reconstruct, and actually enhance the reconstruction quality. In this context, this thesis proposes new iterative reconstruction methods for the inspection of aeronautical parts made by SAFRAN group. In order to alleviate the computational cost due to repeated projection and backprojection operations which model the acquisition process, iterative reconstruction methods can take benefit from the use of high-parallel computing on Graphical Processor Unit (GPU). In this thesis, the implementation on GPU of several pairs of projector and backprojector is detailed. In particular, a new GPU implementation of the matched Separable Footprint pair is proposed. Since many of SAFRAN's industrial parts are piecewise-constant volumes, a Gauss-Markov-Potts prior model is introduced, from which a joint reconstruction and segmentation algorithm is derived. This algorithm is based on a Bayesian approach which enables to explain the role of each parameter. The actual polychromacy of X-rays, which is responsible for scattering and beam-hardening, is taken into account by proposing an error-splitting forward model. Combined with Gauss-Markov-Potts prior on the volume, this new forward model is experimentally shown to bring more accuracy and robustness. At last, the estimation of the uncertainties on the reconstruction is investigated by variational Bayesian approach. In order to have a reasonable computation time, it is highlighted that the use of a matched pair of projector and backprojector is necessary. Note de contenu : 1- X-ray computed tomography : an inverse problem 2- Reconstruction methods in X-ray computed tomography 3- Projection and backprojection operators 4- Gauss-Markov-Potts prior model for joint reconstruction and segmentation 5- Error-splitting forward model and its application with Gauss-Markov-Potts prior 6- Towards the estimation of the uncertainties on the reconstruction by Variational Bayesian Approach 7- Conclusion and perspectives Numéro de notice : 25702 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : Sciences et Technologies de l’Information et de la Communication (STIC) : Traitement du signal et des images : Paris 11 : 2019 Organisme de stage : Safran nature-HAL : Thèse DOI : sans En ligne : https://tel.archives-ouvertes.fr/tel-02110033 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94827

Enhanced resolution stripmap mode using dynamic metasurface antennas / Andreas Pedross-Engel in IEEE Transactions on geoscience and remote sensing, vol 55 n° 7 (July 2017)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 55 n° 7 (July 2017) . - pp 3764 - 3772 Titre : Enhanced resolution stripmap mode using dynamic metasurface antennas Type de document : Article/Communication Auteurs : Andreas Pedross-Engel, Auteur ; Claire M. Watts, Auteur ; David R. Smith, Auteur ; Matthew S. Reynolds, Auteur Année de publication : 2017 Article en page(s) : pp 3764 - 3772 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] faisceau [Termes IGN] radar à antenne synthétique [Termes IGN] rapport signal sur bruit [Termes IGN] traitement du signal Résumé : (Auteur) To maintain sufficient signal-to-noise ratio (SNR) for image reconstruction and image interpretation, conventional synthetic aperture radar (SAR) systems must trade off resolution and scene size. This paper proposes a new SAR mode of operation, which improves resolution while maintaining good SNR and a large scene size. It leverages the unique properties of dynamic metasurface antennas (MSAs) to subsample a large virtual beamwidth utilizing multiple small distinct antenna beams. Due to this parallelization in scene sampling, the constraints on the azimuth sampling rate can be relaxed while maintaining an aliasing-free cross range. Due to the versatile properties of MSAs and their cost effective manufacturing process, this paper proposes SAR systems, which can obtain high resolution images over a wide scene size with lower cost and complexity than competing approaches. Point-spread functions and proof-of-concept SAR simulations are shown to verify this approach. In addition, laboratory experiments using a commercial prototype MSA are presented, which show an improvement of 62% in cross-range resolution of the proposed approach, compared with the cross-range resolution of stripmap mode SAR with the same aperture. Numéro de notice : A2017-486 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2017.2679438 En ligne : http://dx.doi.org/10.1109/TGRS.2017.2679438 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86413 [article]

Comparison of measurement techniques and static theory applied to concrete beam deformation / Petri Rönnholm in Photogrammetric record, vol 24 n° 128 (December 2009 - February 2010)  

Public [article]  inPhotogrammetric record > vol 24 n° 128 (December 2009 - February 2010) . - pp 351 - 371 Titre : Comparison of measurement techniques and static theory applied to concrete beam deformation Type de document : Article/Communication Auteurs : Petri Rönnholm, Auteur ; M. Nuikka, Auteur ; Antero Kukko, Auteur ; Harri Kaartinen, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 351 - 371 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] analyse comparative [Termes IGN] déformation d'édifice [Termes IGN] faisceau [Termes IGN] photogrammétrie terrestre [Termes IGN] positionnement en intérieur [Termes IGN] processus [Termes IGN] surveillance d'ouvrage [Termes IGN] tachéomètre électronique [Termes IGN] télémétrie laser sur satellite Résumé : (Auteur) In this paper, terrestrial laser scanning (TLS), photogrammetric and total station measurements were compared with dial gauge observations in two different loading experiments on a reinforced concrete beam. In the first test, the T-beam was stressed in several loading phases resulting in deformations of up to 13·63 mm. All measuring methods were able to detect deformations with an accuracy of better than 0·38 mm. The theoretical calculations of deflections based on a form of Euler–Bernoulli beam equation, however, underestimated the maximum bending of 4·08 mm. A similar loading experiment was applied on a rectangular concrete beam. In this case, the maximum deformation of the beam was 14·94 mm and measuring accuracies of all methods were better than 0·44 mm. The accuracy of theoretical calculations was better than 2·07 mm. The results indicate that laser scanning could be used as an alternative or complementary method to photogrammetric and total station measurements for detecting structural deformations in buildings. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2009-497 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2009.00548.x En ligne : https://doi.org/10.1111/j.1477-9730.2009.00548.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30126 [article]

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Effects of laser beam alignment tolerance on lidar accuracy / D. Latypov in ISPRS Journal of photogrammetry and remote sensing, vol 59 n° 6 (November 2005)  

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Méthodes modernes en géodésie : contributions au séminaire DVW, 12-14 Avril 1989, 1. Volume 1 / A. Schodlbauer (1990)

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Méthodes modernes en géodésie : contributions au séminaire DVW, 12-14 Avril 1989, 2. Volume 2 / A. Schodlbauer (1990)

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Contrôle photogrammétrique des grands réflecteurs d'ondes par profils lumineux : congrès de Lausanne, 1968, commission 5 / A. Bernin in Bulletin [Société Française de Photogrammétrie], n° 31 (Juillet 1968)

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