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MLMT-CNN for object detection and segmentation in multi-layer and multi-spectral images / Majedaldein Almahasneh in Machine Vision and Applications, vol 33 n° 1 (January 2022)  

Public [article]  inMachine Vision and Applications > vol 33 n° 1 (January 2022) . - n° 9 Titre : MLMT-CNN for object detection and segmentation in multi-layer and multi-spectral images Type de document : Article/Communication Auteurs : Majedaldein Almahasneh, Auteur ; Adeline Paiement, Auteur ; Xianghua Xie, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 9 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] apprentissage dirigé [Termes IGN] apprentissage profond [Termes IGN] atmosphère solaire [Termes IGN] classification par réseau neuronal convolutif [Termes IGN] couche thématique [Termes IGN] détection d'objet [Termes IGN] image multibande [Termes IGN] segmentation d'image Résumé : (auteur) Precisely localising solar Active Regions (AR) from multi-spectral images is a challenging but important task in understanding solar activity and its influence on space weather. A main challenge comes from each modality capturing a different location of the 3D objects, as opposed to typical multi-spectral imaging scenarios where all image bands observe the same scene. Thus, we refer to this special multi-spectral scenario as multi-layer. We present a multi-task deep learning framework that exploits the dependencies between image bands to produce 3D AR localisation (segmentation and detection) where different image bands (and physical locations) have their own set of results. Furthermore, to address the difficulty of producing dense AR annotations for training supervised machine learning (ML) algorithms, we adapt a training strategy based on weak labels (i.e. bounding boxes) in a recursive manner. We compare our detection and segmentation stages against baseline approaches for solar image analysis (multi-channel coronal hole detection, SPOCA for ARs) and state-of-the-art deep learning methods (Faster RCNN, U-Net). Additionally, both detection and segmentation stages are quantitatively validated on artificially created data of similar spatial configurations made from annotated multi-modal magnetic resonance images. Our framework achieves an average of 0.72 IoU (segmentation) and 0.90 F1 score (detection) across all modalities, comparing to the best performing baseline methods with scores of 0.53 and 0.58, respectively, on the artificial dataset, and 0.84 F1 score in the AR detection task comparing to baseline of 0.82 F1 score. Our segmentation results are qualitatively validated by an expert on real ARs. Numéro de notice : A2022-089 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1007/s00138-021-01261-y Date de publication en ligne : 29/11/2021 En ligne : https://doi.org/10.1007/s00138-021-01261-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99500 [article]

Ionospheric error contribution to GNSS single-frequency navigation at the 2014 solar maximum / Raul Orus Perez in Journal of geodesy, vol 91 n° 4 (April 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 4 (April 2017) . - pp 397 - 407 Titre : Ionospheric error contribution to GNSS single-frequency navigation at the 2014 solar maximum Type de document : Article/Communication Auteurs : Raul Orus Perez, Auteur Année de publication : 2017 Article en page(s) : pp 397 - 407 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction ionosphérique [Termes IGN] éruption solaire [Termes IGN] International GNSS Service [Termes IGN] International Reference Ionosphere [Termes IGN] modèle ionosphérique [Termes IGN] récepteur bifréquence [Termes IGN] récepteur monofréquence [Termes IGN] retard ionosphèrique [Termes IGN] signal Galileo [Termes IGN] signal GPS [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) For single-frequency users of the global satellite navigation system (GNSS), one of the main error contributors is the ionospheric delay, which impacts the received signals. As is well-known, GPS and Galileo transmit global models to correct the ionospheric delay, while the international GNSS service (IGS) computes precise post-process global ionospheric maps (GIM) that are considered reference ionospheres. Moreover, accurate ionospheric maps have been recently introduced, which allow for the fast convergence of the real-time precise point position (PPP) globally. Therefore, testing of the ionospheric models is a key issue for code-based single-frequency users, which constitute the main user segment. Therefore, the testing proposed in this paper is straightforward and uses the PPP modeling applied to single- and dual-frequency code observations worldwide for 2014. The usage of PPP modeling allows us to quantify—for dual-frequency users—the degradation of the navigation solutions caused by noise and multipath with respect to the different ionospheric modeling solutions, and allows us, in turn, to obtain an independent assessment of the ionospheric models. Compared to the dual-frequency solutions, the GPS and Galileo ionospheric models present worse global performance, with horizontal root mean square (RMS) differences of 1.04 and 0.49 m and vertical RMS differences of 0.83 and 0.40 m, respectively. While very precise global ionospheric models can improve the dual-frequency solution globally, resulting in a horizontal RMS difference of 0.60 m and a vertical RMS difference of 0.74 m, they exhibit a strong dependence on the geographical location and ionospheric activity. Numéro de notice : A2017-106 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0971-0 En ligne : http://dx.doi.org/10.1007/s00190-016-0971-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84496 [article]

Interference & Einstein: GNSS update / Huibert-Jan Lekkerkerk in Geoinformatics, vol 15 n° 1 (01/01/2012)

Public [article]  inGeoinformatics > vol 15 n° 1 (01/01/2012) . - pp 34 - 36 Titre : Interference & Einstein: GNSS update Type de document : Article/Communication Auteurs : Huibert-Jan Lekkerkerk, Auteur Année de publication : 2012 Article en page(s) : pp 34 - 36 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] éruption solaire [Termes IGN] interférence [Termes IGN] navigation [Termes IGN] signal GNSS Résumé : (Auteur) Some of you may have heard about the experiment at CERN that seems to prove that things can actually go faster than light, something that Einstein said was impossible. So what does a physical experiment have to do with a GNSS update you may ask. Numéro de notice : A2012-029 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31477 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
262-2012011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Validation of international reference ionosphere models using in situ measurements from GRACE K-band ranging system and CHAMP planar Langmuir probe / C. Lee in Journal of geodesy, vol 85 n° 12 (December 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 12 (December 2011) . - pp 921 - 929 Titre : Validation of international reference ionosphere models using in situ measurements from GRACE K-band ranging system and CHAMP planar Langmuir probe Type de document : Article/Communication Auteurs : C. Lee, Auteur ; S. Han, Auteur ; Dieter Bilitza, Auteur ; J. Chung, Auteur Année de publication : 2011 Article en page(s) : pp 921 - 929 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] analyse diachronique [Termes IGN] atmosphère solaire [Termes IGN] bande K [Termes IGN] données CHAMP [Termes IGN] données GRACE [Termes IGN] International Reference Ionosphere [Termes IGN] modèle ionosphérique [Termes IGN] teneur totale en électrons [Termes IGN] zone équatoriale [Termes IGN] zone polaire Résumé : (Auteur) The in situ measurements of electron contents from GRACE K-band (dual-frequency) ranging system and CHAMP planar Langmuir probe were used to validate the international reference ionosphere (IRI) models. The comparison using measurements from year 2003 to 2007 shows a general agreement between data and the model outputs. The improvement in the newer IRI model (IRI-2007) is evident with the measurements from the GRACE satellites orbiting at the higher altitude. We present the comparison between the models and data comprehensively for various cases in solar activity, local time, season, and latitude. The IRI models do not well predict the electron density in the years 2006 and later, when the solar activity is extremely low. The IRI models generally overestimate the electron density during local winter while they underestimate during local summer. In the equatorial region, the large difference at local sunrise lasts for all years and all seasons. The IRI models do not perform well in predicting the anomaly in the polar region such as the Weddell Sea Anomaly. These discrepancies are likely due to smoothed (12-month averaged) solar activity indices used in the IRI models and due to insufficient spherical harmonic representation not able to capture small spatial scales. In near future, further improvement on the IRI models is expected by assimilating those in situ satellite data by implementing higher resolution (spatial and temporal) parameterizations. Numéro de notice : A2011-503 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0442-6 Date de publication en ligne : 30/11/2019 En ligne : https://doi.org/10.1007/s00190-011-0442-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31397 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011121	RAB	Revue	Centre de documentation	En réserve L003	Disponible

High-precision GNSS receivers / N. Blanco-Delgado in GIM international, vol 25 n° 11 (November 2011)

Public [article]  inGIM international > vol 25 n° 11 (November 2011) . - pp 19 - 25 Titre : High-precision GNSS receivers Type de document : Article/Communication Auteurs : N. Blanco-Delgado, Auteur Année de publication : 2011 Article en page(s) : pp 19 - 25 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] interférence [Termes IGN] perturbation ionosphérique [Termes IGN] positionnement par GNSS [Termes IGN] qualité des données [Termes IGN] récepteur GNSS [Termes IGN] signal GNSS [Termes IGN] vent solaire Résumé : (Auteur) What will the new GNSS signals bring to the user of high-precision receivers? This article provides a brief overview of what users can expect from GNSS systems that are currently in the modernisation/development stage, looking at new signals and emerging techniques including coverage of GNSS developments such as GPS, Galileo, GLONASS and Compass/Beidou. In view of the planned timeframe, what we can do to improve the robustness of our receivers with a special focus on interference and the upcoming solar maximum? Numéro de notice : A2011-415 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31194 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
061-2011111	RAB	Revue	Centre de documentation	En réserve L003	Disponible

GNSS and the Ionosphere: What's in Store for the Next Solar Maximum? / A. Jensen in GPS world, vol 22 n° 2 (February 2011)

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Physics of the Earth and the solar system / B. Bertotti (1990)

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vol 33 n° 138 - March 1986 - Solar-terrestrial disturbances of june-september 1982 (Bulletin de Journal of the Radio Research Laboratory) / Ministry of posts and telecommunications  

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vol 33 n° 1 - March 1986 - Solar-terrestrial disturbances of june-september 1982 (Bulletin de Journal of the Radio Research Laboratory) / Ministry of posts and telecommunications  

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Rapports isotopiques dans le système solaire, Paris, 19-22 juin 1984 / Centre national d'études spatiales (1985)

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Les étoiles, le système solaire / Bureau des longitudes (1979)

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Le soleil et la terre / A. Boischot (1966)

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