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3D Hilbert space filling curves in 3D city modeling for faster spatial queries / Uznir Ujang in International journal of 3-D information modeling, vol 3 n° 2 (April - June 2014)  

Public [article]  inInternational journal of 3-D information modeling > vol 3 n° 2 (April - June 2014) . - pp 1 - 18 Titre : 3D Hilbert space filling curves in 3D city modeling for faster spatial queries Type de document : Article/Communication Auteurs : Uznir Ujang, Auteur ; François Anton, Auteur ; Suhaibah Azri, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 1 - 18 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] CityGML [Termes IGN] courbe de Hilbert [Termes IGN] données ouvertes [Termes IGN] espace de Hilbert [Termes IGN] modélisation 3D [Termes IGN] reconstruction 3D du bâti [Termes IGN] requête spatiale [Termes IGN] vitesse [Termes IGN] XML Résumé : (Auteur) The advantages of three dimensional (3D) city models can be seen in various applications including photogrammetry, urban and regional planning, computer games, etc. They expand the visualization and analysis capabilities of Geographic Information Systems on cities, and they can be developed using web standards. However, these 3D city models consume much more storage compared to two dimensional (2 D) spatial data. They involve extra geometrical and topological information together with semantic data. Without a proper spatial data clustering method and its corresponding spatial data access method, retrieving portions of and especially searching these 3D city models, will not be done optimally. Even though current developments are based on an open data model allotted by the Open Geospatial Consortium (OGC) called CityGML, its XML-based structure makes it challenging to cluster the 3D urban objects. In this research, the authors propose an opponent data constellation technique of space-filling curves (3D Hilbert curves) for 3D city model data representation. Unlike previous methods, that try to project 3D or n-dimensional data down to 2D or 3D using Principal Component Analysis (PCA) or Hilbert mappings, in this research, they extend the Hilbert space-filling curve to one higher dimension for 3D city model data implementations. The query performance was tested for single object, nearest neighbor and range search queries using a CityGML dataset of 1,000 building blocks and the results are presented in this paper. The advantages of implementing space-filling curves in 3D city modeling will improve data retrieval time by means of optimized 3D adjacency, nearest neighbor information and 3D indexing. The Hilbert mapping, which maps a sub-interval of the ([0,1]) interval to the corresponding portion of the d-dimensional Hilbert's curve, preserves the Lebesgue measure and is Lipschitz continuous. Depending on the applications, several alternatives are possible in order to cluster spatial data together in the third dimension compared to its clustering in 2 D. Numéro de notice : A2014-652 Affiliation des auteurs : non IGN Thématique : IMAGERIE/INFORMATIQUE Nature : Article DOI : 10.4018/ij3dim.2014040101 En ligne : http://dx.doi.org/10.4018/ij3dim.2014040101 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75102 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
138-2014021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

A query integrity assurance scheme for accessing outsourced spatial databases / W. Ku in Geoinformatica, vol 17 n° 1 (January 2013)  

Public [article]  inGeoinformatica > vol 17 n° 1 (January 2013) . - pp 97 - 124 Titre : A query integrity assurance scheme for accessing outsourced spatial databases Type de document : Article/Communication Auteurs : W. Ku, Auteur ; L. Hu, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 97 - 124 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] base de données localisées [Termes IGN] courbe de Hilbert [Termes IGN] cryptage [Termes IGN] externalisation [Termes IGN] intégrité des données [Termes IGN] plus proche voisin, algorithme du [Termes IGN] protection de la vie privée Résumé : (Auteur) With the trend of cloud computing, outsourcing databases to third party service providers is becoming a common practice for data owners to decrease the cost of managing and maintaining databases in-house. In conjunction, due to the popularity of location-based-services (LBS), the need for spatial data (e.g., gazetteers, vector data) is increasing dramatically. Consequently, there is a noticeably new tendency of outsourcing spatial datasets by data collectors. Two main challenges with outsourcing datasets are to keep the data private (from the data provider) and to ensure the integrity of the query result (for the clients). Unfortunately, most of the techniques proposed for privacy and integrity do not extend to spatial data in a straightforward manner. Hence, recent studies proposed various techniques to support either privacy or integrity (but not both) on spatial datasets. In this paper, for the first time, we propose a technique that can ensure both privacy and integrity for outsourced spatial data. In particular, we first use a one-way spatial transformation method based on Hilbert curves, which encrypts the spatial data before outsourcing and, hence, ensures its privacy. Next, by probabilistically replicating a portion of the data and encrypting it with a different encryption key, we devise a technique for the client to audit the trustworthiness of the query results. We show the applicability of our approach for both k-nearest-neighbor queries and spatial range queries, which are the building blocks of any LBS application. We also design solutions to guarantee the freshness of outsourced spatial databases. Finally, we evaluate the validity and performance of our algorithms with security analyses and extensive simulations. Numéro de notice : A2013-048 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1007/s10707-012-0156-9 Date de publication en ligne : 15/03/2012 En ligne : https://doi.org/10.1007/s10707-012-0156-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32186 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-2013011	RAB	Revue	Centre de documentation	En réserve L003	Disponible