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Fourier-based multi-scale representation and progressive transmission of cartographic curves on the internet / Pengcheng Liu in Cartography and Geographic Information Science, vol 43 n° 5 (November 2016)  

Public [article]  inCartography and Geographic Information Science > vol 43 n° 5 (November 2016) . - pp 454 - 468 Titre : Fourier-based multi-scale representation and progressive transmission of cartographic curves on the internet Type de document : Article/Communication Auteurs : Pengcheng Liu, Auteur ; Xingong Li, Auteur ; Weibo Liu, Auteur ; Tinghua Ai, Auteur Année de publication : 2016 Article en page(s) : pp 454 - 468 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] carte topographique [Termes IGN] contour [Termes IGN] généralisation cartographique automatisée [Termes IGN] géomatique web [Termes IGN] ligne (géométrie) [Termes IGN] représentation multiple [Termes IGN] série de Fourier [Termes IGN] transmission de données [Vedettes matières IGN] Généralisation Résumé : (Auteur) Automatic generation of multi-scale representations from the same spatial data source has been the research focus in map generalization for a long time. Based on the Fourier technique, this paper proposes a continuous, multi-scale representation model for progressive transformation of cartographic curves on the Internet. In our method, all the curves, whether closed or open, are depicted as periodical functions which are further expressed as Fourier series. The convergence degrees of the Fourier series are explored for different kinds of curves, and truncating frequencies are derived based on the similarity between the original and reconstructed curves. Using information theory and the Radical Law in cartography, the relationship between map scales and Fourier frequencies is established. Based on the proposed multi-scale model, we also introduce the principles and implementation of a progressive transmission method. Our method is evaluated using the contours from a topographic map. The results show that our model is a valid approach to multi-scale representation of cartographic curves. Numéro de notice : A2016-695 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/15230406.2015.1088799 En ligne : https://doi.org/10.1080/15230406.2015.1088799 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82034 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
032-2016051	RAB	Revue	Centre de documentation	En réserve L003	Disponible

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