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Understanding spatiotemporel patterns: visual ordening of space and time / Menno-Jan Kraak in Cartographica, vol 42 n° 2 (June 2007)  

Public [article]  inCartographica > vol 42 n° 2 (June 2007) . - pp 153 - 163 Titre : Understanding spatiotemporel patterns: visual ordening of space and time Type de document : Article/Communication Auteurs : Menno-Jan Kraak, Auteur ; Daniel van de Vlag, Auteur Année de publication : 2007 Article en page(s) : pp 153 - 163 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] données spatiotemporelles [Termes IGN] interactivité [Termes IGN] matrice [Termes IGN] modélisation spatio-temporelle [Termes IGN] multiscopie [Termes IGN] objet géographique linéaire [Termes IGN] objet géographique zonal [Termes IGN] visualisation de données Résumé : (Auteur) Il n'est pas facile de trouver des séquences et d'établir des liens à partir de grands ensembles de données multidimensionnelles et multitemporelles, dans le but de comprendre les processus du monde réel. Pour définir le contenu de ces ensembles, les outils d'analyse offrent des solutions intéressantes. Toutefois, il n'existe aucune démarche qui combine les différents types de données susmentionnées. Dans l'article, on suggère une solution de visualisation intégrée pour explorer et analyser les données à la portée de la main. Ce milieu multivue à lien dynamique offre différentes représentations interactives permettant de voir les données et de « jouer » avec elles. Pour la composante du temps, on se sert d'une matrice spatiale d'ordonnancement temporel (TOSM), qui représente à l'aide d'un diagramme la nature temporelle de l'ensemble de données : les rangées représentent le temps, et les colonnes, les unités géographiques. Un test préliminaire a été effectué pour savoir comment la démarche multivue fonctionne en général lors de l'exécution de tâches précises permettant de comprendre des séquences spatiotemporelles. La TOSM est efficace pour les phénomènes naturels (linéaires) comme les rivières et les zones littorales. Dans l'article, on parle aussi de son emploi pour les phénomènes non linéaires, comme les unités administratives. La méthode se base sur l'ordonnancement directionnel et est comparée à d'autres démarches d'ordonnancement, comme les courbes de remplissage de l'espace, le problème du voyageur de commerce et les algorithmes «à plans balayeurs» (plane-sweeping algorithms). Copyright University of Toronto Press Numéro de notice : A2007-340 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.3138/carto.42.2.153 Date de publication en ligne : 29/06/2007 En ligne : https://doi.org/10.3138/carto.42.2.153 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28703 [article]

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Modeling and visualizing dynamic landscape objects and their qualities / Daniel van de Vlag (2006)  

Public Titre : Modeling and visualizing dynamic landscape objects and their qualities Type de document : Thèse/HDR Auteurs : Daniel van de Vlag, Auteur ; Alfred Stein, Directeur de thèse ; Menno-Jan Kraak, Directeur de thèse Editeur : Enschede [Pays Bas] : University of Twente Année de publication : 2006 Collection : ITC Dissertation num. 132 Importance : 170 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-90-8504-384-3 Note générale : bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] analyse multivariée [Termes IGN] arbre de décision [Termes IGN] classification ascendante hiérarchique [Termes IGN] données spatiotemporelles [Termes IGN] incertitude des données [Termes IGN] objet géographique [Termes IGN] ontologie Index. décimale : THESE Thèses et HDR Résumé : (auteur) This thesis focuses on modeling and visualizing dynamic landscape objects and their qualities. It contains ontologies to characterize and model dynamic landscape features using spatial data. It considers their spatial data qualities and visualizes them by explorative methods. In this study, the dynamic landscape features are derived from a coastal movement application within the Netherlands, whereby beaches are subject to nourishment due to severe erosion. The description and classification of beach objects and their processes essentially grounds on the perception of the coastal landscape. Modeling a landscape is a basic agreement on the conceptualization of these features and processes. The aim is to develop a framework for conceptualization of dynamic beach objects, to understand the physical processes involved and to illustrate decision rules adopted in classification of these objects. Also, quality issues related to beach nourishments are studied, visualized and explored, using new visualization techniques. A domain-specific ontology can serve as a framework for the conceptualization of beach objects and their processes. The discrimination into product and problem ontology supports the guidance for classification of these objects and to elucidate which data ‘fit for use’. Data qualities are assessed using a quality matrix, where ontological features are portrayed against quality elements. Elements of positional, thematic and temporal accuracy and data completeness are considered of high importance for the beach nourishment application. The problem and product ontology helps to define two scenarios; the first determined by the regulations from the Ministry for Public Works; the second grounded on the abilities from an existing spatial dataset. A comparison between them shows that 72.8% of the objects suitable and non-suitable for nourishment are correctly classified. A higher overlap is found in areas where actual beach nourishments were carried out. Inaccuracies in attributes, i.e. altitude, vegetation and wetness, influence the determination of the objects. A sensitivity analysis applied on altitude shows that determinate boundaries for beach nourishment objects are not reasonable and consequently should be treated as vague objects. The ontology for beach objects is extended with a spatio-temporal ontology that considers objects to be vague and dynamic. It contains full membership functions for crisp objects, partial membership functions for fuzzy objects and temporal membership functions for dynamic fuzzy objects. The temporal membership functions include seasonal changes of vegetation and daily changes in wetness. A sensitivity analysis shows that the calculated beach nourishment volumes are practically insensitive in relation to assumptions on the temporal membership functions. A spatio-temporal ontology, as an extent of a spatial ontology, is shown to model dynamic processes in landscape studies in a more realistic way. To classify a coastal landscape, I also consider the level of scale. Object hierarchy is essential but is often ignored when collecting and classifying landscape features. A fuzzy decision tree considers a hierarchical structure for classification based on decision rules on object attributes. These attributes are defined on the basis of uncertain parameters that may change in space and time. A Bayesian hierarchical model deals with modeling and handling this uncertainty. In the beach management application, Bayesian hierarchical modeling is applied to obtain posterior probability distributions for several boundary regions. The posterior distributions yield lower and upper limits of membership functions describing boundaries between object classes. In this way, a proper fuzzy decision tree is build that includes the inherent dynamic uncertainty. The spatial information of the application contains large multivariate and multi-temporal datasets. An integrated prototype for visualization and exploration of multivariate spatiotemporal datasets is introduced. It is applied to understand and explain the behaviour of dynamic beach objects and their uncertainties. It consists of the map environment (MAP), a parallel coordinate plot environment (PCP) for visualizing attributes of the dataset, and a temporal ordered space matrix environment (TOSM) for presenting spatio-temporal patterns. The TOSM is a new exploration method and can be seen as a schematized map, whereby the rows in the TOSM environment represent time, the columns represent geographic units, and individual cells are colored according to the value of user defined attributes. The prototype is applied on four case studies. A usability test is performed to test for the differences in the ability to detect patterns in multivariate spatio-temporal datasets for each environment. Test measures are efficiency, effectiveness and user’s satisfaction. Results show that the TOSM environment and the integrated prototype have significantly better performances in efficiency and user’s satisfaction than the MAP and PCP environment. Note de contenu : 1: Introduction 2: Ameland case study 3: An application of problem and product ontologies for the revision of beach nourishments 4: Modeling Dynamic Beach Objects Using Spatio-temporal Ontologies 5: Incorporating Uncertainty via Hierarchical Classification using Fuzzy Decision Trees 6: Temporal Ordered Space Matrix: Representation of Multivariate Spatio-temporal Data 7: Conclusions Numéro de notice : 17248 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Thèse étrangère Note de thèse : PhD thesis : Géomatique : ITC : 2006 En ligne : http://library.wur.nl/WebQuery/wurpubs/348623 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81878

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An application of problem and product ontologies for the revision beach nourishments / Daniel van de Vlag in International journal of geographical information science IJGIS, vol 19 n° 10 (november 2005)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 19 n° 10 (november 2005) . - pp 1057 - 1072 Titre : An application of problem and product ontologies for the revision beach nourishments Type de document : Article/Communication Auteurs : Daniel van de Vlag, Auteur ; Bérengère Vasseur, Auteur ; Alfred Stein, Auteur ; Robert Jeansoulin, Auteur Année de publication : 2005 Article en page(s) : pp 1057 - 1072 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] altitude [Termes IGN] analyse de sensibilité [Termes IGN] classification automatique d'objets [Termes IGN] ensablement [Termes IGN] érosion côtière [Termes IGN] imprécision des données [Termes IGN] littoral [Termes IGN] ontologie [Termes IGN] Pays-Bas [Termes IGN] plage [Termes IGN] système d'information géographique Résumé : (Auteur) An ontological approach in GIS serves as a framework for the conceptualization of processes in the real world. In this paper, we examine an application in coastal change in the Netherlands, whereby beaches are subject to artificial nourishment to offset the effect of severe erosion. The use of ontologies helps to define two scenarios: S1 determined by the regulations from the Ministry for Public Works; S2 grounded on the abilities from an existing spatial dataset. A comparison between S1 and S2 shows that 72.8% of the objects suitable and unsuitable for nourishment are correctly classified. A higher overlap is found in areas where actual beach nourishments were carried out. Inaccuracies in attributes influence the determination of the objects. A sensitivity analysis applied to altitude illustrates a significant increase of objects suitable for nourishment for both scenarios, when altitude is decreased within the lower limit of the root mean square error for the 95% confidence interval. Moreover, the sensitivity of altitude shows that artificial boundaries for beach nourishment objects are not reasonable and consequently should be treated as vague objects. Numéro de notice : A2005-499 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810500032404 En ligne : https://doi.org/10.1080/13658810500032404 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27635 [article]

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079-05092	RAB	Revue	Centre de documentation	En réserve L003	Disponible