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On the generation of time-evolving regional data / T. Tzouramanis in Geoinformatica, vol 6 n° 3 (September - November 2002)  

Public [article]  inGeoinformatica > vol 6 n° 3 (September - November 2002) . - pp 207 - 231 Titre : On the generation of time-evolving regional data Type de document : Article/Communication Auteurs : T. Tzouramanis, Auteur ; M. Vissikalopoulos, Auteur ; Y. Manolopoulos, Auteur Année de publication : 2002 Article en page(s) : pp 207 - 231 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Information géographique [Termes IGN] données spatiotemporelles [Termes IGN] modèle conceptuel de données localisées [Termes IGN] repère de référence Résumé : (Auteur) Benchmarking of spatiotemporal databases is an issue of growing importance. In case large real data sets are not available, benchmarking requires the generation of artificial data sets following the realworld behavior of spatial objects that change their locations, shapes and sizes over time. Only a few innovative papers have recently addressed the topic of spatiotemporal data generators. However, all existing approaches do not consider several important aspects of continuously changing regional data. In this report, a new generator, called generator of timeevolving regional data (G-TERD), for this class of data is presented. The basic concepts that determine the function of G-TERD are the structure of complex 21) regional objects, their color, maximum speed, zoom and rotationangle per time slot, the influence of other moving or static objects on the speed and on the moving direction of an object, the position and movement of the sceneobserver, the statistical distribution of each changing factor and finally, time. Apart from these concepts, the operation and basic algorithmic issues of G-TERD are presented. In the framework developed, the user can control the generator response by setting several parameters values. To demonstrate the use of G-TERD, the generation of a number of sample data sets is presented and commented. The source code and a visualization tool for using and testing the new generator are available on the Web. Thus, it is easy for the user to manipulate the generator according to specific application requirements and at the same time to examine the reliability of the underlying generalized data model. Numéro de notice : A2002-203 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1023/A:1019705618917 En ligne : https://doi.org/10.1023/A:1019705618917 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22118 [article]

Exemplaires(1)

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057-02031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Simultaneous graphic generalization of vector data sets / Lars Harrie in Geoinformatica, vol 6 n° 3 (September - November 2002)  

Public [article]  inGeoinformatica > vol 6 n° 3 (September - November 2002) . - pp 233 - 261 Titre : Simultaneous graphic generalization of vector data sets Type de document : Article/Communication Auteurs : Lars Harrie, Auteur ; Tapani Sarjakoski, Auteur Année de publication : 2002 Article en page(s) : pp 233 - 261 Langues : Anglais (eng) Descripteur : [Termes IGN] C++ [Termes IGN] données vectorielles [Termes IGN] généralisation automatique de données [Termes IGN] généralisation cartographique automatisée [Termes IGN] méthode des moindres carrés [Termes IGN] méthode du gradient conjugué [Termes IGN] objet géographique ponctuel [Termes IGN] optimisation (mathématiques) [Termes IGN] triangulation de Delaunay [Vedettes matières IGN] Généralisation Résumé : (Auteur) Manual cartographic generalization is a simultaneous process. However, most automatic approaches so far have been sequential ; generalization operators are applied one at a time in a certain order. This has been the case both for model generalization (generalization of the conceptual model) and graphic generalization. Our research seeks to demonstrate that the graphic part of cartographic generalization can be formulated as an optimization problem and accordingly be solved in a single step. This paper deals with several issues regarding this optimization approach. Firstly, a set of appropriate analytical constraints for the generalization process is given, as well as rules for when to apply these constraints. In our approach, we are limited to formulating these constraints on point locations. Secondly, leastsquares adjustment is proposed to find the optimal solution according to the constraints. Finally, the conjugate gradients method is recommended for solving the normal equations. A prototype system for simultaneous graphic generalization has been implemented in C++, which communicates with a commercial map production system. Results from three tests of the prototype system are included in the paper. Numéro de notice : A2002-204 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1023/A:1019765902987 En ligne : https://doi.org/10.1023/A:1019765902987 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22119 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-02031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Semi-automated extraction of rivers from digital imagery / C.R. Dillabaugh in Geoinformatica, vol 6 n° 3 (September - November 2002)  

Public [article]  inGeoinformatica > vol 6 n° 3 (September - November 2002) . - pp 263 - 284 Titre : Semi-automated extraction of rivers from digital imagery Type de document : Article/Communication Auteurs : C.R. Dillabaugh, Auteur ; K.O. Niemann, Auteur ; D.E. Richardson, Auteur Année de publication : 2002 Article en page(s) : pp 263 - 284 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] détection de contours [Termes IGN] extraction semi-automatique [Termes IGN] image à haute résolution [Termes IGN] image numérique [Termes IGN] image panchromatique [Termes IGN] image SPOT [Termes IGN] réseau hydrographique [Termes IGN] rivière Résumé : (Auteur) The manual production of vector maps from digital imagery can be a time consuming and costly process. Developing tools to automate this task for specific features, such as roads, has become an important research topic. The purpose of this paper was to present a technique for the semi-automatic extraction of multiple pixel width river features appearing in high resolution satellite imagery. This was accomplished using a two stage, multi resolution procedure. Initial river extraction was performed on low resolution (SPOT multispectral 20 m) imagery. The results from this low resolution extraction were then refined on higher resolution (KFA 1000. panchromatic. 5m) imagery to produce a detailed outline of the channel banks. To perform low resolution extraction a cost surface was generated to represent the combined local evidence of the presence of a river feature. The local evidence of a river was evaluated based on the results of a number of simple operators. Then, with user specified start and end points for the network, rivers were extracted by performing a least cost path search across this surface using the A* algorithm. The low resolution results were transferred to the high resolution imagery as closed contours which provided an estimate of the channel banks. These contours were then fit to the channel banks using the dynamic contours (or snakes) technique. Numéro de notice : A2002-205 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1023/A:1019718019825 En ligne : https://doi.org/10.1023/A:1019718019825 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22120 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-02031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Classifying ambiguities in a visual spatial language / C. Carpentier in Geoinformatica, vol 6 n° 3 (September - November 2002)  

Public [article]  inGeoinformatica > vol 6 n° 3 (September - November 2002) . - pp 285 - 316 Titre : Classifying ambiguities in a visual spatial language Type de document : Article/Communication Auteurs : C. Carpentier, Auteur ; Michel Mainguenaud, Auteur Année de publication : 2002 Article en page(s) : pp 285 - 316 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Information géographique [Termes IGN] interprétation automatique [Termes IGN] langage de modélisation [Termes IGN] langage visuel [Termes IGN] requête spatiale [Termes IGN] système d'information géographique Résumé : (Auteur) Geographic information systems (GIS) manage geographical data and present the results visually using maps. Visual languages are well adapted to query such data. We propose to express queries sent to a GIS using symbolic maps with metaphors. i.e., visual representation of the spatial relationships making up the query. Visual languages suffer from the appearance of ambiguity. We distinguish visual ambiguities from selection ambiguities. Visual ambiguities appear when a given visual representation of a query corresponds with several interpretations. In order to define new spatial relationship, the user points out one (or several) metaphor(s) already available in the restitution space. Selection ambiguities appear when a given selection corresponds with several metaphors. We suggest palliating visual and selection ambiguities by associating a placing method with composition automata. The placing method insures to minimize level of ambiguity. We determine levels of ambiguity and user interaction complexity depending on the required expressive power. The higher the desired expressive power is, the higher the level of ambiguity is and thus the more complex the user interaction is. A prototype has been implemented to validate the placing method and the automaton allowing the highest expressive power. Numéro de notice : A2002-206 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1023/A:1019770003896 En ligne : https://doi.org/10.1023/A:1019770003896 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22121 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-02031	RAB	Revue	Centre de documentation	En réserve L003	Disponible