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Efficient MaxCount and threshold operators of moving objects / S. Anderson in Geoinformatica, vol 13 n° 4 (December 2009)  

Public [article]  inGeoinformatica > vol 13 n° 4 (December 2009) . - pp 355 - 396 Titre : Efficient MaxCount and threshold operators of moving objects Type de document : Article/Communication Auteurs : S. Anderson, Auteur ; P. Revesz, Auteur Année de publication : 2009 Article en page(s) : pp 355 - 396 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] agrégat [Termes IGN] données spatiotemporelles [Termes IGN] objet mobile Résumé : (Auteur) Calculating operators of continuously moving objects presents some unique challenges, especially when the operators involve aggregation or the concept of congestion, which happens when the number of moving objects in a changing or dynamic query space exceeds some threshold value. This paper presents the following six d-dimensional moving object operators: (1) MaxCount (or MinCount), which finds the Maximum (or Minimum) number of moving objects simultaneously present in the dynamic query space at any time during the query time interval. (2) CountRange, which finds a count of point objects whose trajectories intersect the dynamic query space during the query time interval. (3) ThresholdRange, which finds the set of time intervals during which the dynamic query space is congested. (4) ThresholdSum, which finds the total length of all the time intervals during which the dynamic query space is congested. (5) ThresholdCount, which finds the number of disjoint time intervals during which the dynamic query space is congested. And (6) ThresholdAverage, which finds the average length of time of all the time intervals when the dynamic query space is congested. For these operators separate algorithms are given to find only estimate or only precise values. Experimental results from more than 7,500 queries indicate that the estimation algorithms produce fast, efficient results with error under 5%. Copyright Springer Numéro de notice : A2009-332 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-008-0050-7 En ligne : https://doi.org/10.1007/s10707-008-0050-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29962 [article]

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Update-efficient indexing of moving objects in road networks / J. Chen in Geoinformatica, vol 13 n° 4 (December 2009)  

Public [article]  inGeoinformatica > vol 13 n° 4 (December 2009) . - pp 397 - 424 Titre : Update-efficient indexing of moving objects in road networks Type de document : Article/Communication Auteurs : J. Chen, Auteur ; X. Meng, Auteur Année de publication : 2009 Article en page(s) : pp 397 - 424 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] arbre-R [Termes IGN] base de données spatiotemporelles [Termes IGN] index spatial [Termes IGN] objet mobile [Termes IGN] réseau routier Résumé : (Auteur) Recent advances in wireless sensor networks and positioning technologies have boosted new applications that manage moving objects. In such applications, a dynamic index is often built to expedite evaluation of spatial queries. However, the development of efficient indexes is a challenge due to frequent object movement. In this paper, we propose a new update-efficient index method for moving objects in road networks. We introduce a dynamic data structure, called adaptive unit, to group neighboring objects with similar movement patterns. To reduce updates, an adaptive unit captures the movement bounds of the objects based on a prediction method, which considers road-network constraints and the stochastic traffic behavior. A spatial index (e.g., R-tree) for the road network is then built over the adaptive unit structures. Simulation experiments, carried on two different datasets, show that an adaptive-unit based index is efficient for both updating and querying performances. Copyright Springer Numéro de notice : A2009-333 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1007/s10707-008-0052-5 En ligne : https://doi.org/10.1007/s10707-008-0052-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29963 [article]

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Automated processing for map generation using web services / Moritz Neun in Geoinformatica, vol 13 n° 4 (December 2009)  

Public [article]  inGeoinformatica > vol 13 n° 4 (December 2009) . - pp 425 - 452 Titre : Automated processing for map generation using web services Type de document : Article/Communication Auteurs : Moritz Neun, Auteur ; Robert Weibel, Auteur ; Dirk Burghardt, Auteur Année de publication : 2009 Article en page(s) : pp 425 - 452 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] architecture orientée services [Termes IGN] généralisation cartographique automatisée [Termes IGN] géomatique web [Termes IGN] optimisation (mathématiques) [Termes IGN] service web géographique [Termes IGN] traitement parallèle [Termes IGN] traitement réparti Résumé : (Auteur) In map generalization various operators are applied to the features of a map in order to maintain and improve the legibility of the map after the scale has been changed. These operators must be applied in the proper sequence and the quality of the results must be continuously evaluated. Cartographic constraints can be used to define the conditions that have to be met in order to make a map legible and compliant to the user needs. The combinatorial optimization approaches shown in this paper use cartographic constraints to control and restrict the selection and application of a variety of different independent generalization operators into an optimal sequence. Different optimization techniques including hill climbing, simulated annealing and genetic deep search are presented and evaluated experimentally by the example of the generalization of buildings in blocks. All algorithms used in this paper have been implemented in a web services framework. This allows the use of distributed and parallel processing in order to speed up the search for optimized generalization operator sequences. Copyright Springer Numéro de notice : A2009-334 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1007/s10707-008-0054-3 En ligne : https://doi.org/10.1007/s10707-008-0054-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29964 [article]

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A meeting scheduling problem respecting time and space / Frédéric Berger in Geoinformatica, vol 13 n° 4 (December 2009)  

Public [article]  inGeoinformatica > vol 13 n° 4 (December 2009) . - pp 453 - 481 Titre : A meeting scheduling problem respecting time and space Type de document : Article/Communication Auteurs : Frédéric Berger, Auteur ; Olivier Klein, Auteur ; D. Nussbaum, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 453 - 481 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Algorithmique [Termes IGN] diagramme de Voronoï [Termes IGN] géomètrie algorithmique [Termes IGN] système d'information géographique Résumé : (Auteur) We consider the problem of determining suitable meeting times and locations for a group of participants wishing to schedule a new meeting subject to already scheduled meetings possibly held at a number of different locations. Each participant must be able to reach the new meeting location, attend for the entire duration, and reach the next meeting location on time. In particular, we give two solutions to the problem instance where each participant has two scheduled meetings separated by a free time interval. We present an O(n logn) algorithm for n participants obtained by purely geometrical arguments. Our second approach uses the concept of LP-type problems and leads to a randomized algorithm with expected running time O(n). We also consider a graph-based model where participants belong to different groups and can travel along the edges of a graph. For the meeting, only one member out of each group is required. The resulting problem can be solved using furthest color Voronoi diagrams on graphs. Copyright Springer Numéro de notice : A2009-335 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE Nature : Article DOI : 10.1007/s10707-008-0053-4 En ligne : https://doi.org/10.1007/s10707-008-0053-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29965 [article]

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Web data retrieval: solving spatial range queries using k-nearest neighbor searches / W. Bae in Geoinformatica, vol 13 n° 4 (December 2009)  

Public [article]  inGeoinformatica > vol 13 n° 4 (December 2009) . - pp 483 - 514 Titre : Web data retrieval: solving spatial range queries using k-nearest neighbor searches Type de document : Article/Communication Auteurs : W. Bae, Auteur ; S.H. Kim, Auteur ; S. Alkobaisi, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 483 - 514 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Infrastructure de données [Termes IGN] classification barycentrique [Termes IGN] géomatique web [Termes IGN] interface web [Termes IGN] recherche d'information géographique [Termes IGN] requête spatiale [Termes IGN] système d'information géographique Résumé : (Auteur) As Geographic Information Systems (GIS) technologies have evolved, more and more GIS applications and geospatial data are available on the web. Spatial objects in a given query range can be retrieved using spatial range query - one of the most widely used query types in GIS and spatial databases. However, it can be challenging to retrieve these data from various web applications where access to the data is only possible through restrictive web interfaces that support certain types of queries. A typical scenario is the existence of numerous business web sites that provide their branch locations through a limited “nearest location” web interface. For example, a chain restaurant’s web site such as McDonalds can be queried to find some of the closest locations of its branches to the user’s home address. However, even though the site has the location data of all restaurants in, for example, the state of California, it is difficult to retrieve the entire data set efficiently due to its restrictive web interface. Considering that k-Nearest Neighbor (k-NN) search is one of the most popular web interfaces in accessing spatial data on the web, this paper investigates the problem of retrieving geospatial data from the web for a given spatial range query using only k-NN searches. Based on the classification of k-NN interfaces on the web, we propose a set of range query algorithms to completely cover the rectangular shape of the query range (completeness) while minimizing the number of k-NN searches as possible (efficiency). We evaluated the efficiency of the proposed algorithms through statistical analysis and empirical experiments using both synthetic and real data sets. Copyright Springer Numéro de notice : A2009-336 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-008-0055-2 En ligne : https://doi.org/10.1007/s10707-008-0055-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29966 [article]

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