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Descriptive measures of point distributions summarized with respect to spatial scale in visualization / Yukio Sadahiro in Cartographica, vol 53 n° 3 (Fall 2018)  

Public [article]  inCartographica > vol 53 n° 3 (Fall 2018) . - pp 185 - 202 Titre : Descriptive measures of point distributions summarized with respect to spatial scale in visualization Type de document : Article/Communication Auteurs : Yukio Sadahiro, Auteur Année de publication : 2018 Article en page(s) : pp 185 - 202 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse géovisuelle [Termes IGN] carte de répartition par points [Termes IGN] carte thématique [Termes IGN] méthode fondée sur le noyau [Vedettes matières IGN] Géovisualisation Résumé : (Auteur) Visual exploration plays a critical role in point pattern analysis. It permits analysts to grasp a wide variety of spatial patterns in point distributions that are not necessarily detectable by mathematical and statistical methods. Since spatial patterns are scale-dependent, grid and kernel density maps are effective in analysis that can visualize point distributions at various scales from small to large. Visual exploration of these maps, however, takes a considerable amount of time even if the maps are generated automatically in GIS software. In addition, visual exploration inevitably becomes subjective and unstable when treating numerous maps simultaneously. It is not easy to evaluate and memorize spatial patterns in maps in a consistent and objective way. To resolve the problem, this article proposes new quantitative measures summarizing the characteristics of point distributions. The measures can be visualized as maps that help analysts to capture the overall spatial pattern of point distributions efficiently. Numerical experiments and applications to real data analysis are performed to test the validity of the proposed measures. The results reveal the effectiveness of the measures, as well as their shortcomings, to be resolved in future research. Numéro de notice : A2018-482 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3138/cart.53.3.2017-0023 Date de publication en ligne : 01/10/2018 En ligne : https://doi.org/10.3138/cart.53.3.2017-0023 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91207 [article]

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Trajectories of moving objects on a network: detection of similarities, visualization of relations, and classification of trajectories / Yukio Sadahiro in Transactions in GIS, vol 17 n° 1 (February 2013)  

Public [article]  inTransactions in GIS > vol 17 n° 1 (February 2013) . - pp 18 - 40 Titre : Trajectories of moving objects on a network: detection of similarities, visualization of relations, and classification of trajectories Type de document : Article/Communication Auteurs : Yukio Sadahiro, Auteur ; Raymond Lay, Auteur ; T. Kobayashi, Auteur Année de publication : 2013 Article en page(s) : pp 18 - 40 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] analyse de groupement [Termes IGN] analyse spatiale [Termes IGN] classification dirigée [Termes IGN] graphe [Termes IGN] itinéraire [Termes IGN] mesure de similitude [Termes IGN] migration animale [Termes IGN] objet mobile [Termes IGN] relation topologique [Termes IGN] réseau de transport [Termes IGN] similitude [Termes IGN] visualisation de données Résumé : (Auteur) Development in techniques of spatial data acquisition enables us to easily record the trajectories of moving objects. Movement of human beings, animals, and birds can be captured by GPS loggers. The obtained data are analyzed by visualization, clustering, and classification to detect patterns frequently or rarely found in trajectories. To extract a wider variety of patterns in analysis, this article proposes a new method for analyzing trajectories on a network space. The method first extracts primary routes as subparts of trajectories. The topological relations among primary routes and trajectories are visualized as both a map and a graph-based diagram. They permit us to understand the spatial and topological relations among the primary routes and trajectories at both global and local scales. The graph-based diagram also permits us to classify trajectories. The representativeness of primary routes is evaluated by two numerical measures. The method is applied to the analysis of daily travel behavior of one of the authors. Technical soundness of the method is discussed as well as empirical findings. Numéro de notice : A2013-038 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1467-9671.2012.01330.x Date de publication en ligne : 09/10/2012 En ligne : https://doi.org/10.1111/j.1467-9671.2012.01330.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32176 [article]

Analysis of the spatial relations among point distributions on a discrete space / Yukio Sadahiro in International journal of geographical information science IJGIS, vol 24 n°7-8 (july 2010)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 24 n°7-8 (july 2010) . - pp 997 - 1014 Titre : Analysis of the spatial relations among point distributions on a discrete space Type de document : Article/Communication Auteurs : Yukio Sadahiro, Auteur Année de publication : 2010 Article en page(s) : pp 997 - 1014 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] établissement d'enseignement [Termes IGN] graphe [Termes IGN] Japon [Termes IGN] relation spatiale [Termes IGN] relation topologique [Termes IGN] représentation discrète Résumé : (Auteur) This paper proposes a method of analyzing spatial relations among point distributions on a discrete space. Spatial topology and proximity are discussed in an integrated framework at both local and global scales. Local relations are described by geographical representations, whereas global relations are visualized by graph representations. The latter also provide a means of classifying the point distributions. The proposed method is applied to school location planning in Japan. The results reveal the appealing properties of the method and provide empirical findings. Numéro de notice : A2010-318 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810903213296 En ligne : https://doi.org/10.1080/13658810903213296 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30512 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-2010041	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-2010042	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Accuracy of quantized Voronoi diagrams / Yukio Sadahiro in International journal of geographical information science IJGIS, vol 20 n° 10 (november 2006)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 20 n° 10 (november 2006) . - pp 1173 - 1189 Titre : Accuracy of quantized Voronoi diagrams Type de document : Article/Communication Auteurs : Yukio Sadahiro, Auteur ; T. Tominaga, Auteur Année de publication : 2006 Article en page(s) : pp 1173 - 1189 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Statistiques [Termes IGN] approximation [Termes IGN] diagramme de Voronoï [Termes IGN] maille triangulaire [Termes IGN] objet géographique [Termes IGN] tessellation Résumé : (Auteur) Quantization of spatial objects, which usually means vector-to-raster conversion in GIS and remote sensing, is a basic operation used for handling spatial data from data creation to visualization. Since quantization is an approximation of spatial objects, it inevitably yields errors in measuring their properties such as area, perimeter, diameter, and so forth. This paper discusses the accuracy of a quantized Voronoi diagram, a spatial tessellation generated from a set of points. A measure is proposed to evaluate the accuracy of the area of Voronoi regions calculated after quantization. In one-dimensional space the measure is expressed as an explicit function of the expected number of generators in a cell. In two-dimensional space, on the other hand, the measure is defined by an implicit function, whose approximation is derived in an explicit form. These functions permit us to evaluate the accuracy of quantization in relation to the size of lattice cells and the density of Voronoi generators. This leads to an appropriate choice of a lattice to keep the quality of a quantized Voronoi diagram at a desirable level. Copyright Taylor & Francis Numéro de notice : A2006-455 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE Nature : Article DOI : 10.1080/13658810600816748 En ligne : https://doi.org/10.1080/13658810600816748 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28179 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-06101	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-06102	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Stability of the surface generated from distributed points of uncertain location / Yukio Sadahiro in International journal of geographical information science IJGIS, vol 17 n° 2 (march 2003)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 17 n° 2 (march 2003) . - pp 139 - 156 Titre : Stability of the surface generated from distributed points of uncertain location Type de document : Article/Communication Auteurs : Yukio Sadahiro, Auteur Année de publication : 2003 Article en page(s) : pp 139 - 156 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Information géographique [Termes IGN] analyse mathématique [Termes IGN] analyse visuelle [Termes IGN] erreur [Termes IGN] géopositionnement [Termes IGN] imprécision des données [Termes IGN] incertitude géométrique [Termes IGN] stabilité [Termes IGN] système d'information géographique [Termes IGN] visualisation de données Résumé : (Auteur) Conversion of a point distribution into a surface is one of the spatial operations used in GIS. This supports the visual analysis of point patterns, which is usually followed by more sophisticated statistical and mathematical analysis. If the location of points is uncertain, however, the surface obtained becomes unstable and consequently the results of analysis may be unreliable. Though unavoidable in spatial data, locational uncertainty has been rather neglected in the context of spatial analysis. To fill this gap, this paper proposes a method for representing and analysing the stability of the surface generated from an uncertain point distribution. The surface stability is represented by a scalar function called the slope stability function. Its definition, calculation procedure, visualization method, and summary indices are proposed. The method is evaluated through an empirical study, and some findings are shown which help us understand the effect of the smoothing parameter, locational uncertainty, and spatial pattern of points on the stability of a surface. Numéro de notice : A2003-093 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/713811751 En ligne : https://doi.org/10.1080/713811751 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22389 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-03021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-03022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

A graphical method for exploring spatiotemporal point distributions / Yukio Sadahiro in Cartography and Geographic Information Science, vol 29 n° 2 (April 2002)  

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Analysis of surface changes using primitive events / Yukio Sadahiro in International journal of geographical information science IJGIS, vol 15 n° 6 (september 2001)  

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Accuracy of count data transferred through the areal weighting interpolation method / Yukio Sadahiro in International journal of geographical information science IJGIS, vol 14 n° 1 (january 2000)  

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