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Automatic and accurate extraction of road intersections from raster maps / Yao-Yi Chiang in Geoinformatica, vol 13 n° 2 (June 2009)  

Public [article]  inGeoinformatica > vol 13 n° 2 (June 2009) . - pp 121 - 157 Titre : Automatic and accurate extraction of road intersections from raster maps Type de document : Article/Communication Auteurs : Yao-Yi Chiang, Auteur ; C. Shahabi, Auteur ; Craig A. Knoblock, Auteur ; C.C. Chen, Auteur Année de publication : 2009 Article en page(s) : pp 121 - 157 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] carrefour [Termes IGN] carte numérique [Termes IGN] conflation [Termes IGN] connexité (topologie) [Termes IGN] données maillées [Termes IGN] extraction automatique [Termes IGN] extraction du réseau routier [Termes IGN] intégration de données [Termes IGN] réseau routier Résumé : (Auteur) Since maps are widely available for many areas around the globe, they provide a valuable resource to help understand other geospatial sources such as to identify roads or to annotate buildings in imagery. To utilize the maps for understanding other geospatial sources, one of the most valuable types of information we need from the map is the road network, because the roads are common features used across different geospatial data sets. Specifically, the set of road intersections of the map provides key information about the road network, which includes the location of the road junctions, the number of roads that meet at the intersections (i.e., connectivity), and the orientations of these roads. The set of road intersections helps to identify roads on imagery by serving as initial seed templates to locate road pixels. Moreover, a conflation system can use the road intersections as reference features (i.e., control point set) to align the map with other geospatial sources, such as aerial imagery or vector data. In this paper, we present a framework for automatically and accurately extracting road intersections from raster maps. Identifying the road intersections is difficult because raster maps typically contain much information such as roads, symbols, characters, or even contour lines. We combine a variety of image processing and graphics recognition methods to automatically separate roads from the raster map and then extract the road intersections. The extracted information includes a set of road intersection positions, the road connectivity, and road orientations. For the problem of road intersection extraction, our approach achieves over 95% precision (correctness) with over 75% recall (completeness) on average on a set of 70 raster maps from a variety of sources. Copyright Springer Numéro de notice : A2009-073 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1007/s10707-008-0046-3 En ligne : https://doi.org/10.1007/s10707-008-0046-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29703 [article]

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Cloaking locations for anonymous location based services: a hybrid approach / C. Zhang in Geoinformatica, vol 13 n° 2 (June 2009)  

Public [article]  inGeoinformatica > vol 13 n° 2 (June 2009) . - pp 159 - 182 Titre : Cloaking locations for anonymous location based services: a hybrid approach Type de document : Article/Communication Auteurs : C. Zhang, Auteur ; Y. Huang, Auteur Année de publication : 2009 Article en page(s) : pp 159 - 182 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] service fondé sur la position [Termes IGN] téléphonie mobile [Termes IGN] utilisateur nomade Résumé : (Auteur) An important privacy issue in Location Based Services is to hide a user’s identity while still provide quality location based services. Previous work has addressed the problem of locational $\mathcal{K}$-anonymity either based on centralized or decentralized schemes. However, a centralized scheme relies on an anonymizing server (AS) for location cloaking, which may become the performance bottleneck when there are large number of clients. More importantly, holding information in a centralized place is more vulnerable to malicious attacks. A decentralized scheme depends on peer communication to cloak locations and is more scalable. However, it may pose too much computation and communication overhead to the clients. The service fulfillment rate may also be unsatisfied especially when there are not enough peers nearby. This paper proposes a new hybrid framework called HiSC that balances the load between the AS and mobile clients. HiSC partitions the space into base cells and a mobile client claims a surrounding area consisting of base cells. The number of mobile clients in the surrounding cells is kept and updated at both client and AS sides. A mobile client can either request cloaking service from the centralized AS or use a peer-to-peer approach for spatial cloaking based on personalized privacy, response time, and service quality requirements. HiSC can elegantly distribute the work load between the AS and the mobile clients by tuning one system parameter base cell size and two client parameters - surrounding cell size and tolerance count. By integrating salient features of two schemes, HiSC successfully preserves query anonymity and provides more scalable and consistent service. Both the AS and the clients can enjoy much less work load. Additionally, we propose a simple yet effective random range shifting algorithm to prevent possible privacy leakage that would exist in the original P2P approach. Our experiments show that HiSC can elegantly balance the work load based on privacy requirements and client distribution. HiSC provides close to optimal service quality. Meanwhile, it reduces the response time by more than an order of magnitude from both the P2P scheme and the centralized scheme when anonymity level(value of $\mathcal{K}$) or number of clients is large. It also reduces the update message cost of the AS by nearly 6 times and the peer searching message cost of the clients by more than an order of magnitude. Copyright Springer Numéro de notice : A2009-074 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10707-008-0047-2 En ligne : https://doi.org/10.1007/s10707-008-0047-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29704 [article]

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Yet another map algebra / J. Cerveira Cordeiro in Geoinformatica, vol 13 n° 2 (June 2009)  

Public [article]  inGeoinformatica > vol 13 n° 2 (June 2009) . - pp 183 - 202 Titre : Yet another map algebra Type de document : Article/Communication Auteurs : J. Cerveira Cordeiro, Auteur ; G. Camara, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 183 - 202 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Langages informatiques [Termes IGN] analyse spatiale [Termes IGN] automate [Termes IGN] langage de modélisation [Termes IGN] Map Algebra [Termes IGN] modèle cartographique [Termes IGN] voisinage (relation topologique) Résumé : (Auteur) This paper describes features of a language approach for map algebra based on the use of algebraic expressions that satisfy a concise formalism. To be consistent with formal approaches such as geoalgebra and image algebra, the proposed algebraic expressions are suitable not only for the usual modeling of layers but also to describe variable neighborhoods and zones. As a compromise between language and implementation issues we present an implementation strategy based on the theory of automata. The result is an efficient way of implementing map algebra that simplifies its use on environmental and dynamic models without going too far from its well-known paradigm. Copyright Springer Numéro de notice : A2009-075 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1007/s10707-008-0045-4 En ligne : https://doi.org/10.1007/s10707-008-0045-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29705 [article]

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Shape deformation in continuous map generalization / J. Danciger in Geoinformatica, vol 13 n° 2 (June 2009)  

Public [article]  inGeoinformatica > vol 13 n° 2 (June 2009) . - pp 203 - 221 Titre : Shape deformation in continuous map generalization Type de document : Article/Communication Auteurs : J. Danciger, Auteur ; S. Devadoss, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 203 - 221 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] cartogramme [Termes IGN] déformation géométrique [Termes IGN] généralisation cartographique automatisée [Termes IGN] géomètrie algorithmique [Termes IGN] mise à l'échelle [Termes IGN] programmation par contraintes [Termes IGN] relation topologique [Vedettes matières IGN] Généralisation Résumé : (Auteur) Given a collection of regions on a map, we seek a method of continuously altering the regions as the scale is varied. This is formalized and brought to rigor as well-defined problems in homotopic deformation. We ask the regions to preserve topology, area-ratios, and relative position as they change over time. A solution is presented using differential methods and computational geometric techniques. Most notably, an application of this method is used to provide an algorithm to obtain cartograms. Copyright Springer Numéro de notice : A2009-076 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1007/s10707-008-0049-0 En ligne : https://doi.org/10.1007/s10707-008-0049-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29706 [article]

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Urban granularities: a data structure for cognitively ergonomic route directions / Alexander Klippel in Geoinformatica, vol 13 n° 2 (June 2009)  

Public [article]  inGeoinformatica > vol 13 n° 2 (June 2009) . - pp 223 - 247 Titre : Urban granularities: a data structure for cognitively ergonomic route directions Type de document : Article/Communication Auteurs : Alexander Klippel, Auteur ; S. Hansen, Auteur ; Stephan Winter, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 223 - 247 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] cognition [Termes IGN] direction [Termes IGN] granularité (informatique) [Termes IGN] îlot urbain [Termes IGN] modèle logique de données [Termes IGN] quartier [Termes IGN] route Résumé : (Auteur) This paper addresses a data structure specification for route directions that incorporates essential aspects of cognitive information processing. Specifically, we characterize levels of granularity in route directions as the result of the hierarchical organization of urban spatial knowledge. We discuss changes of granularity in route directions that result from combining elementary route information into higher-order elements (so called spatial chunking). We provide a framework that captures the pertinent aspects of spatial chunking. The framework is based on established principles used—from a cognitive perspective—for changing the granularity in route directions. The data structure we specify based on this framework allows us to bridge the gap between results from behavioral cognitive science studies and requirements of information systems. We discuss the theoretical underpinning of the core elements of the data structure and provide examples for its application. Copyright Springer Numéro de notice : A2009-077 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1007/s10707-008-0051-6 En ligne : https://doi.org/10.1007/s10707-008-0051-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29707 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-09021	RAB	Revue	Centre de documentation	En réserve L003	Disponible