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Robust hyperspectral vision-based classification for multi-season weed mapping / Y. Zhang in ISPRS Journal of photogrammetry and remote sensing, vol 69 (April 2012)
[article]
Titre : Robust hyperspectral vision-based classification for multi-season weed mapping Type de document : Article/Communication Auteurs : Y. Zhang, Auteur ; D. Slaughter, Auteur ; E. Staab, Auteur Année de publication : 2012 Article en page(s) : pp 65 - 73 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] apprentissage automatique
[Termes IGN] Californie (Etats-Unis)
[Termes IGN] classification bayesienne
[Termes IGN] cultures
[Termes IGN] herbe
[Termes IGN] identification de plantes
[Termes IGN] image hyperspectrale
[Termes IGN] photogrammétrie métrologique
[Termes IGN] réflectance végétale
[Termes IGN] système expert
[Termes IGN] variation saisonnièreRésumé : (Auteur) This study investigated the robustness of hyperspectral image-based plant recognition to seasonal variability in a natural farming environment in the context of automated in-row weed control. A machine vision system was developed and equipped with a CCD camera integrated with a line-imaging spectrograph for close-range weed sensing and mapping. Three canonical Bayesian classifiers were developed using canopy reflectance (400–795 nm) collected over three seasons for tomato and weeds. The performance of the three season-specific classifiers was tested by changing environmental conditions, resulting in an increase in total error rate of up to 36%. Global calibration across the complete span of the three seasons produced overall classification accuracies of 85.0%, 90.0% and 92.7%, respectively, for 2005, 2006 and 2008. To improve the stability of global classifier over multiple seasons, a multiclassifier system was constructed with three canonical Bayesian classifiers optimized for the three seasons individually. This system was tested on a data set simulating an upcoming season with field conditions similar to that in 2005. The system increased the total discrimination accuracy to 95.8% for the tested season under simulation. This method provided an innovative direction for achieving robust plant recognition over multiple seasons by integrating expert knowledge from historical data that most closely matched the new field environment. Numéro de notice : A2012-194 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2012.02.006 En ligne : https://doi.org/10.1016/j.isprsjprs.2012.02.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31641
in ISPRS Journal of photogrammetry and remote sensing > vol 69 (April 2012) . - pp 65 - 73[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-2012031 SL Revue Centre de documentation Revues en salle Disponible Study of seasonal-scale atmospheric water cycle with ground-based GPS receivers, radiosondes and NWP models over Morocco / Achraf Koulali in Atmospheric Research, vol 104 - 105 (February 2012)
[article]
Titre : Study of seasonal-scale atmospheric water cycle with ground-based GPS receivers, radiosondes and NWP models over Morocco Type de document : Article/Communication Auteurs : Achraf Koulali, Auteur ; Driss Ouazar, Auteur ; Olivier Bock , Auteur ; Abdelali Fadil, Auteur Année de publication : 2012 Article en page(s) : pp 273 - 291 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Canaries
[Termes IGN] circulation atmosphérique
[Termes IGN] données GPS
[Termes IGN] données météorologiques
[Termes IGN] Maroc
[Termes IGN] précipitation
[Termes IGN] radiosondage
[Termes IGN] récepteur GPS
[Termes IGN] retard troposphérique zénithal
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] variation saisonnièreRésumé : (Auteur) This study investigates the seasonal variation of precipitable water vapor, moisture transport and precipitation over Morocco and the Canary Islands using data from ground-based GPS receivers, radiosondes, GPCP and NCEP reanalysis II. In a first part, the datasets are inter-compared. Humidity biases are evidenced in both radiosonde observations (dry) and NCEP reanalysis (dry and wet) compared to GPS. Moisture transport and precipitation from the reanalysis and observations show a good agreement. Precipitable water shows a maximum in late summer whereas precipitation is peaking in winter and spring over Morocco. Moisture transport occurs preferentially in two layers, below and above 850 hPa. The monthly mean precipitable water variation over Morocco is controlled by the upper layer zonal and meridional moisture flux. Precipitation is rather controlled by the lower layer moisture flux and the upper layer meridional flux. The GPS tropospheric gradients show also a consistent seasonal evolution, which is explained by gradients both in the thickness of the troposphere and in the precipitable water vapor. Tropospheric gradients are correlated with moisture fluxes, mostly in the upper layer, and may therefore provide valuable information for meteorology and climatology. Numéro de notice : A2012-737 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.atmosres.2011.11.002 Date de publication en ligne : 13/11/2011 En ligne : https://doi.org/10.1016/j.atmosres.2011.11.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91460
in Atmospheric Research > vol 104 - 105 (February 2012) . - pp 273 - 291[article]Entwicklung eines Kalman-Filters zur Bestimmung kurzzeitiger Variationen des Erdschwerefeldes aus daten der Satellitenmission GRACE / E. Kurtenbach (2012)
Titre : Entwicklung eines Kalman-Filters zur Bestimmung kurzzeitiger Variationen des Erdschwerefeldes aus daten der Satellitenmission GRACE Titre original : Development of a Kalman filter to derive short-term variations of the Earth's gravity field from GRACE data Type de document : Thèse/HDR Auteurs : E. Kurtenbach, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2012 Collection : DGK - C Sous-collection : Dissertationen num. 683 Importance : 120 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5095-2 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] corrélation automatique de points homologues
[Termes IGN] crénelage
[Termes IGN] données GRACE
[Termes IGN] filtre de Kalman
[Termes IGN] série temporelle
[Termes IGN] variation temporelleRésumé : (Auteur) The gravitational field and its temporal variations represent an important observable for the monitoring of the Earth's system. The satellite mission GRACE (Gravity Recovery And Climate Experiment) is, for the first time, able to measure gravity field variations with homogeneous global coverage. Nevertheless, the predicted GRACE accuracy has not been reached yet, partly due to the insufficient representation of the temporal variations in terms of monthly mean fields. In this thesis, an approach is presented which allows the calculation of daily GRACE solutions with the goal of modeling short-term gravity field variations. This time series can on the one hand be used to improve the knowledge of the underlying geophysical processes. On the other hand the daily GRACE solutions can also be used to improve the monthly mean fields. Increasing the temporal resolution is accompanied by a loss of accuracy due to insufficient data coverage. Therefore, additional information in terms of temporal and spatial correlations of the expected gravity signal is introduced into the analysis process. The combination of the GRACE observations and the correlation patterns is then performed within a Kalman filter framework. In a simulation study, the performance of the approach at hand is investigated and, in a second step, applied to real GRACE LIB data. Comparisons to independent data sets, i.e. vertical displacements of GPS stations and ocean bottom pressure time series, reveal that the daily GRACE time series contains geophysically interpretable signal. Furthermore, the daily GRACE time series can be used to significantly reduce the effects of temporal aliasing in the processing of monthly mean gravity field solutions. Numéro de notice : 14619 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62670 Documents numériques
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14619_dgk-c-683_kurtenbach.pdfAdobe Acrobat PDF Accuracy assessment of the GPS-TEC calibration constants by means of a simulation technique / Jacques Conte in Journal of geodesy, vol 85 n° 10 (October 2011)
[article]
Titre : Accuracy assessment of the GPS-TEC calibration constants by means of a simulation technique Type de document : Article/Communication Auteurs : Jacques Conte, Auteur ; F. Azpilicueta, Auteur ; C. Brunini, Auteur Année de publication : 2011 Article en page(s) : pp 707 - 714 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse diachronique
[Termes IGN] GPS en mode différentiel
[Termes IGN] ionosphère
[Termes IGN] propagation ionosphérique
[Termes IGN] rayonnement solaire
[Termes IGN] teneur totale en électrons
[Termes IGN] variation saisonnièreRésumé : (Auteur) During the last 2 decades, Global Positioning System (GPS) measurements have become a very important data-source for ionospheric studies. However, it is not a direct and easy task to obtain accurate ionospheric information from these measurements because it is necessary to perform a careful estimation of the calibration constants affecting the GPS observations, the so-called differential code biases (DCBs). In this paper, the most common approximations used in several GPS calibration methods, e.g. the La Plata Ionospheric Model (LPIM), are applied to a set of specially computed synthetic slant Total Electron Content datasets to assess the accuracy of the DCB estimation in a global scale scenario. These synthetic datasets were generated using a modified version of the NeQuick model, and have two important features: they show a realistic temporal and spatial behavior and all a-priori DCBs are set to zero by construction. Then, after the application of the calibration method the deviations from zero of the estimated DCBs are direct indicators of the accuracy of the method. To evaluate the effect of the solar activity radiation level the analysis was performed for years 2001 (high solar activity) and 2006 (low solar activity). To take into account seasonal changes of the ionosphere behavior, the analysis was repeated for three consecutive days close to each equinox and solstice of every year. Then, a data package comprising 24 days from approximately 200 IGS permanent stations was processed. In order to avoid unwanted geomagnetic storms effects, the selected days correspond to periods of quiet geomagnetic conditions. The most important results of this work are: i) the estimated DCBs can be affected by errors around +8 TECu for high solar activity and +3 TECu for low solar activity; and ii) DCB errors present a systematic behavior depending on the modip coordinate, that is more evident for the positive modip region. Numéro de notice : A2011-435 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0477-8 Date de publication en ligne : 15/05/2011 En ligne : https://doi.org/10.1007/s00190-011-0477-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31213
in Journal of geodesy > vol 85 n° 10 (October 2011) . - pp 707 - 714[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2011101 RAB Revue Centre de documentation En réserve L003 Disponible Singular spectrum analysis of global mean sea level variations / S. Khelifa in Bulletin des sciences géographiques, n° 26 (octobre 2011)
[article]
Titre : Singular spectrum analysis of global mean sea level variations Type de document : Article/Communication Auteurs : S. Khelifa, Auteur ; M. Belbachir, Auteur ; M. Hadad, Auteur Année de publication : 2011 Article en page(s) : pp 17 - 22 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altimétrie satellitaire par radar
[Termes IGN] altitude
[Termes IGN] analyse de spectre singulier
[Termes IGN] hauteurs de mer
[Termes IGN] montée du niveau de la mer
[Termes IGN] niveau moyen des mers
[Termes IGN] série temporelle
[Termes IGN] variation temporelleRésumé : (Auteur) Le thème développé à travers cet article porte sur l'analyse des séries temporelles d'anomalies moyennes de hauteur de la mer (MSLA) d'altimétrie spatiale par le spectre singulier (SSA). Le but de cette étude est de caractériser et de quantifier la variabilité à long terme du niveau de la mer. Les données utilisées lors du traitement sont constituées d'une série hebdomadaire d'anomalies moyennes de hauteur de la mer issues des satellites d'altimétrie spatiale, conduite entre 1993 et 2009. Les résultats obtenus ont montré que la SAA est bien adaptée pour l'extraction simultanée de la tendance non linéaire et des signaux saisonniers contenus dans les séries temporelles MSLA. La tendance, le signal annuel et semi annuel représentent respectivement 93.36%, 6.01 % et 0.34% du signal total. La tendance estimée de 2.88 mm/an de niveau global de la mer est similaire aux récents résultats publiés par AVISO Altimétrie sur la tendance de niveau global de la mer qui est d'environs 2.92 mm/an. Numéro de notice : A2011-499 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31393
in Bulletin des sciences géographiques > n° 26 (octobre 2011) . - pp 17 - 22[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 253-2011011 RAB Revue Centre de documentation En réserve L003 Disponible Simulation study of the influence of the ionospheric layer height in the thin layer ionospheric model / C. Brunini in Journal of geodesy, vol 85 n° 9 (September 2011)PermalinkThree-dimensional humidity retrieval using a network of compact microwave radiometers to correct for variations in wet tropospheric path delay in spaceborne interferometric SAR imagery / S. Sahoo in IEEE Transactions on geoscience and remote sensing, vol 49 n° 9 (September 2011)PermalinkGRACE-derived surface water mass anomalies by energy integral approach: application to continental hydrology / Guillaume Ramillien in Journal of geodesy, vol 85 n° 6 (June 2011)PermalinkLes mouvements séculaires du géocentre, le réchauffement climatique et l'ITRF / Laurent Métivier in Bulletin d'information scientifique et technique de l'IGN, n° 77 (avril 2011)PermalinkMonitoring elevation variations in leaf phenology of deciduous broadleaf forests from SPOT/VEGETATION time-series / Dominique Guyon in Remote sensing of environment, vol 115 n° 2 ([15/02/2011])PermalinkEvaluation of the impact of atmospheric pressure loading modeling on GNSS data analysis / Rolf Dach in Journal of geodesy, vol 85 n° 2 (February 2011)PermalinkPermalinkThe large‐scale water cycle of the West African monsoon / Olivier Bock in Atmospheric Science Letters, vol 12 n° 1 (January - March 2011)PermalinkWest African Monsoon water cycle: 1. A hybrid water budget data set / Rémi Meynadier in Journal of geophysical research : Atmospheres, vol 115 n° D19 (2010)PermalinkGlobal gravity field determination using the GPS measurements made onboard the low Earth orbiting satellite CHAMP / Lars Prange (2010)Permalink