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Storm event representation and analysis based on a directed spatiotemporal graph model / W. Liu in International journal of geographical information science IJGIS, vol 30 n° 5-6 (May - June 2016)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 30 n° 5-6 (May - June 2016) . - pp 948 - 969 Titre : Storm event representation and analysis based on a directed spatiotemporal graph model Type de document : Article/Communication Auteurs : W. Liu, Auteur ; Xingong Li, Auteur ; David A. Rahn, Auteur Année de publication : 2016 Article en page(s) : pp 948 - 969 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] dynamique spatiale [Termes IGN] Etats-Unis [Termes IGN] graphe [Termes IGN] image radar [Termes IGN] réflectivité [Termes IGN] série temporelle [Termes IGN] tempête [Termes IGN] temps instantané Résumé : (Auteur) Large amounts of time series of spatial snapshot data have been collected or generated for the monitoring and modeling of environmental systems. Those time series of data also provide the opportunity to study the movements and dynamics of many different natural phenomena. While the snapshot organization is conceptually simple and straightforward, it does not directly capture or represent the dynamic characteristics of the phenomena. This study presents computational methods to identify dynamic events from time series of spatial snapshots. Events are represented as directed spatiotemporal graphs to characterize their initiation, development, movement, and cessation. Graph-based algorithms are used to analyze the dynamics of the events. The method is applied to time series of high-resolution radar reflectivity images during one of the deadliest storm outbreaks that impacted 15 states of southeastern United States between 23 and 29 April 2011. As shown in this case study, convective storm events identified using our methods are consistent with previous studies, and our analysis confirms that the left split/merger occurs more than right split/merger in those convective storm events, which confirms theory, numerical simulations, and other observed case studies. While this study does not differentiate between storm modes, the method shows potential for capturing a more detailed climatology of precipitation characteristics. Numéro de notice : A2016-290 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2015.1081910 En ligne : https://doi.org/10.1080/13658816.2015.1081910 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80869 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-2016032	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-2016031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

GNSS RF Compatibility assessment: Interference among GPS, Galileo and Compass / W. Liu in GPS world, vol 21 n° 12 (December 2010)

Public [article]  inGPS world > vol 21 n° 12 (December 2010) . - pp 32 - 40 Titre : GNSS RF Compatibility assessment: Interference among GPS, Galileo and Compass Type de document : Article/Communication Auteurs : W. Liu, Auteur ; X. Zhan, Auteur ; L. Liu, Auteur ; M. Niu, Auteur Année de publication : 2010 Article en page(s) : pp 32 - 40 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] compatibilité [Termes IGN] configuration (matériel informatique) [Termes IGN] dégradation du signal [Termes IGN] géonavigateur [Termes IGN] interférence [Termes IGN] rapport signal sur bruit [Termes IGN] récepteur GNSS [Termes IGN] récepteur mixte [Termes IGN] signal BeiDou [Termes IGN] signal Galileo [Termes IGN] signal GNSS [Termes IGN] signal GPS Résumé : (Auteur) A comprehensive methodology combines spectral-separation and code-tracking spectral-sensitivity coefficients to analyze interference among GPS, Galileo, and Compass. The authors propose determining the minimum acceptable degradation of effective carrier-to-noise-density ratio, considering all receiver processing phases, and conclude that each GNSS can provide a sound basis for compatibility with other GNSS with respect to the special receiver configuration. Numéro de notice : A2010-540 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30732 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
067-2010121	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Detection of spatial conflicts between rivers and contours in digital map updating / J. Chen in International journal of geographical information science IJGIS, vol 21 n° 9-10 (october 2007)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 21 n° 9-10 (october 2007) . - pp 1093 - 1114 Titre : Detection of spatial conflicts between rivers and contours in digital map updating Type de document : Article/Communication Auteurs : J. Chen, Auteur ; W. Liu, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 1093 - 1114 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] conflit d'espace [Termes IGN] contour [Termes IGN] généralisation cartographique automatisée [Termes IGN] mise à jour cartographique [Termes IGN] placement automatique des objets [Termes IGN] relation topologique Résumé : (Auteur) In the process of topographic map updating, spatial conflicts (inconsistency) between rivers and contours may be created. This project studies the particularity and complexity of the relationships between rivers and contours, and develops a method for automatic detection of the spatial conflicts between them. This method consists of a refined descriptive spatial model (called a topological chain), an algorithm for the computation of spatial relations, and a set of rules for the determination of spatial conflicts. In the spatial relation model, the topological relationships, order relationships, and metric relationships are integrated to describe the line-line spatial relationships. The rules are derived from the natural relations between rivers and contours in the real world. The effectiveness of this method has been verified by using the national 1:50 000 topographic map databases. An accuracy of 91% has been achieved. Copyright Taylor & Francis Numéro de notice : A2007-558 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1080/13658810701300071 En ligne : https://doi.org/10.1080/13658810701300071 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28921 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-07061	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-07062	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Uncertainty and confidence in land cover classification using a hybrid classifier approach / W. Liu in Photogrammetric Engineering & Remote Sensing, PERS, vol 70 n° 8 (August 2004)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 70 n° 8 (August 2004) . - pp 963 - 971 Titre : Uncertainty and confidence in land cover classification using a hybrid classifier approach Type de document : Article/Communication Auteurs : W. Liu, Auteur ; Sucharita Gopal, Auteur ; Curtis E. Woodcock, Auteur Année de publication : 2004 Article en page(s) : pp 963 - 971 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] Amérique du nord [Termes IGN] classification hybride [Termes IGN] classification par arbre de décision [Termes IGN] classification par réseau neuronal [Termes IGN] image NOAA-AVHRR [Termes IGN] incertitude des données [Termes IGN] occupation du sol Résumé : (Auteur) Traditional methods of land cover classification and mapping are limited in providing spatial data on the uncertainty of map labels. In this paper, we present a hybrid classifier approach using Decision Tree (DT) and ARTMAP neural network to providing confidence or uncertainty information via majority voting and other rules. The hybrid classifier is tested with AVHRR data to mapping land cover of North America. The two classifiers (DT and ARTMAP) tend to make predictive errors in different contexts. They show 68% agreement in classifying land cover of North America. A set of rules is developed to assign class labels for pixels where the two classifiers disagree. Levels of confidence in the hybrid classification derived from their individual voting (ARTmAP) and probability (DT) are used to assign confidence. The approach outlined in this paper produces two products a hybrid classification map as well as a confidence map based on the two classification schemes. The hybrid approach seems suitable to tackle a variety of classification problems in remote sensing and may ultimately aid map users in making more informed decisions. Numéro de notice : A2004-309 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.70.8.963 En ligne : https://doi.org/10.14358/PERS.70.8.963 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26836 [article]

Comparing ARTMAP neural network with the maximum-likelihood classifier for detecting urban change / K.C. Seto in Photogrammetric Engineering & Remote Sensing, PERS, vol 69 n° 9 (September 2003)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 69 n° 9 (September 2003) . - pp 981 - 990 Titre : Comparing ARTMAP neural network with the maximum-likelihood classifier for detecting urban change Type de document : Article/Communication Auteurs : K.C. Seto, Auteur ; W. Liu, Auteur Année de publication : 2003 Article en page(s) : pp 981 - 990 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] agrégation spatiale [Termes IGN] analyse comparative [Termes IGN] classification par maximum de vraisemblance [Termes IGN] classification par réseau neuronal [Termes IGN] croissance urbaine [Termes IGN] détection de changement [Termes IGN] image Landsat-TM [Termes IGN] milieu urbain Résumé : (Auteur) Urbanization has profound effects on the environment at local, regional, and global scales. Effective detection of urban change using remote sensing data will be an essential component of global environmental change research, regional planning. and natural resource management. This paper presents results from an ARTMAP neural network to detect urban change with Landsat TM images from two periods. Classification of urban change, and, in particular, conversion of agriculture to urban, was statistically more accurate with ARTMAP than with a more conventional technique, the Bayesian maximum-likelihood classifier (MLC). The effect of different levels of class aggregation on the performance of change detection was also explored with ARTMAP and MLC. Because ARTMAP explicitly allows "many-to-one "mapping, classification using coarse class resolution and fine class resolution training data generated similar results. Together, these results suggest that ARTMAP can reduce labor and computational costs associated with assembling training data while concurrently generating more accurate urban change detection results. Numéro de notice : A2003-228 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.69.9.981 En ligne : http://dx.doi.org/10.14358/PERS.69.9.981 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22523 [article]

A stochastic process-based model for the positional error of line segments in GIS / Wei Shi in International journal of geographical information science IJGIS, vol 14 n° 1 (january 2000)  

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