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GMOBench: Benchmarking generic moving objects / Jianqiu Xu in Geoinformatica, vol 19 n° 2 (April - June 2015)  

Public [article]  inGeoinformatica > vol 19 n° 2 (April - June 2015) . - pp 227 - 276 Titre : GMOBench: Benchmarking generic moving objects Type de document : Article/Communication Auteurs : Jianqiu Xu, Auteur ; Ralf Hartmut Güting, Auteur ; Xiaolin Qin, Auteur Année de publication : 2015 Article en page(s) : pp 227 - 276 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] arbre-R [Termes IGN] base de données orientée objet [Termes IGN] implémentation (informatique) [Termes IGN] index spatial [Termes IGN] mobilité humaine [Termes IGN] mobilité urbaine [Termes IGN] objet mobile [Termes IGN] point de repère [Termes IGN] requête spatiale [Termes IGN] test de performance Résumé : (auteur) In real world scenarios, people’s movement include several environments rather than one, for example, road network, pavement areas and indoor. This imposes a new challenge for moving objects database that the complete trip needs to be managed by a database system. In the meantime, novel queries regarding different transportation modes should also be supported. Since existing methods are limited to trips in a single environment and do not support queries on moving objects with different transportation modes, new technologies are essentially needed in a database system. In this paper, we introduce a benchmark called GMOBench that aims to evaluate the performance of a database system managing moving objects in different environments. GMOBench is settled in a realistic scenario and is comprised of three components: (1) a data generator with the capability of creating a scalable set of trips representing the complete movement of humans (both indoor and outdoor); (2) a set of carefully designed and benchmark queries; (3) Mode-RTree, an index structure for managing generic moving objects. The generator defines some parameters so that users can control the characteristics of results. We create the benchmark data in such a way that the dataset can mirror important characteristics and real world distributions of human mobility. Efficient access methods and optimization techniques are developed for query processing. In particular, we propose an index structure called Mode-RTree to manage moving objects in different environments. By employing the proposed index, the cost of benchmark queries is greatly reduced. GMOBench is implemented in a real database system to have a practical result. We perform an extensive experimental study on comprehensive datasets to evaluate the performance. The results show that by using the Mode-RTree we achieve significant performance improvement over the baseline method, demonstrating the effectiveness and efficiency of our approaches. Numéro de notice : A2015-488 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-014-0211-9 Date de publication en ligne : 26/06/2014 En ligne : https://doi.org/10.1007/s10707-014-0211-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77281 [article]

Adaptive generation of variable-scale network maps for small displays based on line density distribution / Zhilin Li in Geoinformatica, vol 19 n° 2 (April - June 2015)  

Public [article]  inGeoinformatica > vol 19 n° 2 (April - June 2015) . - pp 277 - 295 Titre : Adaptive generation of variable-scale network maps for small displays based on line density distribution Type de document : Article/Communication Auteurs : Zhilin Li, Auteur ; Peng Ti, Auteur Année de publication : 2015 Article en page(s) : pp 277 - 295 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes IGN] analyse de données [Termes IGN] carte thématique [Termes IGN] densité [Termes IGN] échelle des données [Termes IGN] échelle variable [Termes IGN] généralisation cartographique automatisée [Termes IGN] lisibilité perceptive [Termes IGN] petit écran Résumé : (auteur) This paper presents an integrated strategy for adaptive generation of variable-scale network maps for different small displays. It is based on the line density distribution and comprised of three steps, i.e. (a) to estimate the line density by a grid-based method, (b) to adaptively generate variable-scale maps based on density distribution for given display sizes and (c) to improve the map readability by map generalization. The proposed strategy has been tested by using two real-life network datasets, with a statistical analysis and a perceptual evaluation. Experimental results show that this strategy is able to better exploit the limited map space so as to significantly improve map clarity and readability and at the same time to preserve map recognition ability compared to its original shape. Numéro de notice : A2015-489 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-014-0212-8 Date de publication en ligne : 03/06/2014 En ligne : https://doi.org/10.1007/s10707-014-0212-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77282 [article]

On reverse-k-nearest-neighbor joins / Tobias Emrich in Geoinformatica, vol 19 n° 2 (April - June 2015)  

Public [article]  inGeoinformatica > vol 19 n° 2 (April - June 2015) Titre : On reverse-k-nearest-neighbor joins Type de document : Article/Communication Auteurs : Tobias Emrich, Auteur ; Hans-Peter Kriege, Auteur ; Peer Kröger, Auteur ; et al., Auteur Année de publication : 2015 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] analyse comparative [Termes IGN] classification barycentrique [Termes IGN] espace métrique [Termes IGN] espace vectoriel [Termes IGN] jointure spatiale [Termes IGN] requête (informatique) [Termes IGN] requête spatiale inverse Résumé : (auteur) A reverse k-nearest neighbour (RkNN) query determines the objects from a database that have the query as one of their k-nearest neighbors. Processing such a query has received plenty of attention in research. However, the effect of running multiple RkNN queries at once (join) or within a short time interval (bulk/group query) has only received little attention so far. In this paper, we analyze different types of RkNN joins and provide a classification of existing RkNN join algorithms. We discuss possible solutions for solving the non-trivial variants of the problem in vector spaces, including self and mutual pruning strategies. Further, we generalize the developed algorithms to general metric spaces. During an extensive performance analysis we provide evaluation results showing the IO and CPU performance of the compared algorithms for a wide range of different setups and suggest appropriate query algorithms for specific scenarios. Numéro de notice : A2015-490 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-014-0215-5 Date de publication en ligne : 23/08/2014 En ligne : https://doi.org/10.1007/s10707-014-0215-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77283 [article]

A dilution-matching-encoding compaction of trajectories over road networks / Ranit Gotsman in Geoinformatica, vol 19 n° 2 (April - June 2015)  

Public [article]  inGeoinformatica > vol 19 n° 2 (April - June 2015) . - pp 331-364 Titre : A dilution-matching-encoding compaction of trajectories over road networks Type de document : Article/Communication Auteurs : Ranit Gotsman, Auteur ; Yaron Kanza, Auteur Année de publication : 2015 Article en page(s) : pp 331-364 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes IGN] calcul d'itinéraire [Termes IGN] chemin le plus court, algorithme du [Termes IGN] géocodage [Termes IGN] noeud [Termes IGN] positionnement par GPS [Termes IGN] réseau routier [Termes IGN] stockage de données [Termes IGN] vectorisation Résumé : (auteur) Many devices nowadays record traveled routes as sequences of GPS locations. With the growing popularity of smartphones, millions of such routes are generated each day, and many routes have to be stored locally on the device or transmitted to a remote database. It is, thus, essential to encode the sequences, in order to decrease the volume of the stored or transmitted data. In this paper we study the problem of encoding routes over a vectorial road network (map), where GPS locations can be associated with vertices or with road segments. We consider a three-step process of dilution, map-matching and coding, which helps reducing the amount of transmitted data between the cellular device and remote servers. We present two methods to code routes. The first method represents the given route as a sequence of greedy paths. We provide two algorithms to generate a greedy-path code for a sequence of n vertices on the map. The first algorithm has O(n) time complexity, and the second one has O(n 2) time complexity, but it is optimal, meaning that it generates the shortest possible greedy-path code. Decoding a greedy-path code can be done in O(n) time. The second method encodes a route as a sequence of shortest paths. We provide algorithms to generate unidirectional and bidirectional optimal shortest-path codes. Encoding and decoding a shortest-path code can be done in O(k n 2 logn) time, where k is the length of the produced code, assuming the graph valency is bounded. Our experimental evaluation shows that shortest-path codes are more compact than greedy-path codes, justifying the larger time complexity. Numéro de notice : A2015-491 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-014-0216-4 Date de publication en ligne : 11/08/2014 En ligne : https://doi.org/10.1007/s10707-014-0216-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77284 [article]