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Ocean Loading in Brittany, Northwest France: Impact of the GPS Analysis Strategy / Joëlle Nicolas (2012)
Titre : Ocean Loading in Brittany, Northwest France: Impact of the GPS Analysis Strategy Type de document : Article/Communication Auteurs : Joëlle Nicolas, Auteur ; Stéphane Durand, Auteur ; Mathilde Vergnolle, Auteur ; Laurent Morel, Auteur ; Stavros A. Melachroinos, Auteur ; Marie-Noëlle Bouin , Auteur ; François Fund, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2012 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 137 Conférence : IAG 2009, 7th Hotine-Marussi Symposium on Mathematical Geodesy 06/06/2009 10/06/2009 Rome Italie Proceedings Springer Importance : pp 367 - 372 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse comparative
[Termes IGN] Bernese
[Termes IGN] GAMIT
[Termes IGN] GINS
[Termes IGN] GIPSY-OASIS
[Termes IGN] surcharge océaniqueRésumé : (auteur) In this contribution, we analyze the impact of different GPS processing strategies on ocean tide loading estimation. We use continuous GPS data acquired during a 4-month campaign performed in 2004 in Brittany, Northwest France. Since the expected geodynamical signal in the estimated positions is exceeding the typical GPS data analysis noise, this data set can be used to compare the results obtained with different analysis software packages. Moreover, in this specific case we need short sub-daily solutions to study short-period signals instead of classical 24 h-solutions. The GPS capability for measuring 3D ocean tide loading deformation has already been assessed, but since we are looking for the finest signal as the one induced by the shallow water constituents, it is essential to be sure that the position time series represent a geodynamical signal and are not biased by the data processing strategy used. To analyze the possible effect of the methodology used on the geodynamical results, we compare different solutions computed with different strategies (Double Differencing and Precise Point Positioning) with various GPS analysis software packages (Bernese, GAMIT, GINS, and GIPSY/OASIS). We show that the different solution consistency is at the level of 1–3 mm. We also show that the data processing strategy has a mean effect of about 10–20% of the ocean tide loading signal amplitude. Numéro de notice : C2009-001 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/978-3-642-22078-4_55 Date de publication en ligne : 18/10/2011 En ligne : https://doi.org/10.1007/978-3-642-22078-4_55 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102737 WebGIS performance tests / H. Dai in GIM international, vol 26 n° 1 (January 2012)
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Titre : WebGIS performance tests Type de document : Article/Communication Auteurs : H. Dai, Auteur ; L. Chen, Auteur ; C. Chen, Auteur Année de publication : 2012 Article en page(s) : pp 23 - 27 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web
[Termes IGN] analyse comparative
[Termes IGN] architecture à trois niveaux
[Termes IGN] diffusion de données
[Termes IGN] serveur d'application
[Termes IGN] test de performance
[Termes IGN] traitement réparti
[Termes IGN] WebSIGRésumé : (Auteur) A webGIS is usually constructed as a multi-tiers architecture basically consisting for the client side, the server side and the database component. From the client side, users send queries or requests to the server via (wireless) internet. Next the server communicates with database, where the requested information is compiled by the database server. Finally, the result is sent to the client. With the rapid growth of WebGIS application in 2010, the authors tested the performance of two models: centralized and distributed. Numéro de notice : A2012-006 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31454
in GIM international > vol 26 n° 1 (January 2012) . - pp 23 - 27[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 061-2012011 RAB Revue Centre de documentation En réserve L003 Disponible An assessment of internal neural network parameters affecting image classification accuracy / L. Zhou in Photogrammetric Engineering & Remote Sensing, PERS, vol 77 n° 12 (December 2011)
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Titre : An assessment of internal neural network parameters affecting image classification accuracy Type de document : Article/Communication Auteurs : L. Zhou, Auteur ; X. Yang, Auteur Année de publication : 2011 Article en page(s) : pp 1233 - 1240 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] analyse comparative
[Termes IGN] classification par maximum de vraisemblance
[Termes IGN] classification par réseau neuronal
[Termes IGN] image Landsat-ETM+
[Termes IGN] Perceptron multicouche
[Termes IGN] précision de la classification
[Termes IGN] précision des donnéesRésumé : (Auteur) Neural networks are attractive intelligence techniques increasingly being used to classify remote sensor imagery. However, their performance is contingent upon a wide range of algorithm and non-algorithm factors. Despite significant progresses being made over the past two decades, there is no consistent guidance that has been established to automate the use of neural networks in remote sensing. The purpose of this study was to assess several internal parameters affecting image classification accuracy by multi-layer-perceptron (mlp) neural networks. The MLP networks have been considered as the most popular neural network architecture. We carefully configured and trained a set of neural network models with different internal parameter settings. Then, we used these models to classify an Enhanced Thematic Mapper Plus (ETM+) image into several major land cover categories, and the accuracy of each classified map was assessed. The results reveal that number of hidden layers, activation function, and training rate can substantially affect the classification accuracy and that a neural network with appropriate internal parameters can lead to a significant classification accuracy improvement for urban land covers when comparing to the outcome by the Gaussian Maximum Likelihood (GML) classifier. These findings can help design efficient neural network models for improved performance. Numéro de notice : A2011-488 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.77.12.1233 En ligne : https://doi.org/10.14358/PERS.77.12.1233 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31382
in Photogrammetric Engineering & Remote Sensing, PERS > vol 77 n° 12 (December 2011) . - pp 1233 - 1240[article]Relevance assessment of full-waveform lidar data for urban area classification / Clément Mallet in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 6 supplement (December 2011)
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Titre : Relevance assessment of full-waveform lidar data for urban area classification Type de document : Article/Communication Auteurs : Clément Mallet , Auteur ; Frédéric Bretar, Auteur ; Michel Roux, Auteur ; Uwe Soergel, Auteur ; Christian Heipke, Auteur Année de publication : 2011 Article en page(s) : pp 71 - 84 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] analyse comparative
[Termes IGN] classification automatique
[Termes IGN] classification par séparateurs à vaste marge
[Termes IGN] données lidar
[Termes IGN] lidar à retour d'onde complète
[Termes IGN] méthode des moindres carrés
[Termes IGN] pertinence
[Termes IGN] semis de points
[Termes IGN] zone urbaineRésumé : (Auteur) Full-waveform lidar data are increasingly being available. Morphological features can be retrieved from the echoes composing the waveforms, and are now extensively used for a large variety of land-cover mapping issues. However, the genuine contribution of these features with respect to those computed from standard discrete return lidar systems has been barely theoretically investigated. This paper therefore aims to study the potential of full-waveform data through the automatic classification of urban areas in building, ground, and vegetation points. Two waveform processing methods, namely a non-linear least squares method and a marked point process approach, are used to fit the echoes both with symmetric and asymmetric modeling functions. The performance of the extracted full-waveform features for the classification problem are then compared to a large variety of multiple-pulse features thanks to three feature selection methods. A support vector machines classifier is finally used to label the point cloud according to various scenarios based on the rank of the features. This allows to find the best classification strategy as well as the minimal feature subsets allowing to achieve the highest classification accuracy possible for each of the three feature selection methods. The results show that the echo amplitude as well as two features computed from the radiometric calibration of full-waveform data, namely the cross-section and the backscatter coefficient, significantly contribute to the high classification accuracies reported in this paper (around 95%). Conversely, features extracted from the non Gaussian modelling of the echoes are not relevant for the discrimination of vegetation, ground, and buildings in urban areas. Numéro de notice : A2011-520 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.09.008 Date de publication en ligne : 12/10/2011 En ligne : http://www.sciencedirect.com/science/article/pii/S0924271611001055 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31414
in ISPRS Journal of photogrammetry and remote sensing > vol 66 n° 6 supplement (December 2011) . - pp 71 - 84[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-2011071 SL Revue Centre de documentation Revues en salle 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)
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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 polaireRésumé : (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
in Journal of geodesy > vol 85 n° 12 (December 2011) . - pp 921 - 929[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2011121 RAB Revue Centre de documentation En réserve L003 Disponible Visual comparison of moving-window kriging models / Urška Demšar in Cartographica, vol 46 n° 4 (December 2011)PermalinkIntercomparison and validation of techniques for spectral unmixing of hyperspectral images : a planetary case study / X. Ceamanos in IEEE Transactions on geoscience and remote sensing, vol 49 n° 11 Tome 1 (November 2011)PermalinkValidation of GOCE gravity field models by means of orbit residuals and geoid comparisons / Thomas Gruber in Journal of geodesy, vol 85 n° 11 (November /2011)PermalinkDamage assessment of 2010 Haïti earthquake with post-earthquake satellite image by support vector selection and adaptation / Gülsen Taskin Kaya in Photogrammetric Engineering & Remote Sensing, PERS, vol 77 n° 10 (October 2011)PermalinkEstimation of forest stand volume, tree density and biodiversity using Landsat ETM + Data, comparison of linear and regression tree analyses / Jahangir Mohammadi in Procedia Environmental Sciences, vol 7 (2011)PermalinkÉclairer le choix des outils de simulation des changements des modes d’occupation et d’usages des sols : Une approche comparative / J. Mas in Revue internationale de géomatique, vol 21 n° 3 (septembre - novembre 2011)PermalinkPrediction of the error induced by topography in satellite microwave radiometric observations / Luca Pulvirenti in IEEE Transactions on geoscience and remote sensing, vol 49 n° 9 (September 2011)PermalinkThe right attitude: Experimenting with GPS on board high-altitude balloons / P. Buist in GPS world, vol 22 n° 9 (September 2011)PermalinkAn evaluation of solar radiation pressure strategies for the GPS constellation / Ant Sibthorpe in Journal of geodesy, vol 85 n° 8 (August 2011)PermalinkEmpirical comparison of full-waveform Lidar algorithms: range extraction and discrimination performance / C. Parrish in Photogrammetric Engineering & Remote Sensing, PERS, vol 77 n° 8 (August 2011)Permalink