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Robust high-quality interpolation of regions to moving regions / Florian Heinz in Geoinformatica, vol 20 n° 3 (July - September 2016)  

Public [article]  inGeoinformatica > vol 20 n° 3 (July - September 2016) . - pp 385 – 413 Titre : Robust high-quality interpolation of regions to moving regions Type de document : Article/Communication Auteurs : Florian Heinz, Auteur ; Ralf Hartmut Güting, Auteur Année de publication : 2016 Article en page(s) : pp 385 – 413 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] analyse spatio-temporelle [Termes IGN] base de données orientée objet [Termes IGN] données spatiotemporelles [Termes IGN] implémentation (informatique) [Termes IGN] interpolation linéaire [Termes IGN] méthode robuste [Termes IGN] objet mobile [Termes IGN] représentation du changement Résumé : (auteur) With the rise of moving object databases it is possible to store and process spatial and temporal data, for example geometrical structures together with the information about how these behave over intervals of time. For simple objects like moving points the spatiotemporal development is derived from the start and end position in space and time, which is then linearly interpolated. For moving regions, especially with changing shapes, it is more challenging to obtain the necessary data to represent them. An elegant and intuitive solution is to create an algorithm, which automatically interpolates the moving region from the start and end shape over a specified time interval. Two papers on this topic have been published in the past, each focussing on different aspects of this so-called Region Interpolation Problem. This paper tries to combine the advantages and improve these approaches to provide high-quality interpolations while maintaining robustness even in border cases. This results in the implementation of a library, which can be easily integrated into existing moving objects database systems, as for example the DBMS Secondo developed at the FernUniversität in Hagen. Numéro de notice : A2016-376 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-015-0240-z Date de publication en ligne : 12/11/2015 En ligne : https://doi.org/https://doi.org/10.1007/s10707-015-0240-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81143 [article]

Location K-anonymity in indoor spaces / Joon-Seok Kim in Geoinformatica, vol 20 n° 3 (July - September 2016)  

Public [article]  inGeoinformatica > vol 20 n° 3 (July - September 2016) . - pp 415–451 Titre : Location K-anonymity in indoor spaces Type de document : Article/Communication Auteurs : Joon-Seok Kim, Auteur ; Ki-Joune Li, Auteur Année de publication : 2016 Article en page(s) : pp 415–451 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] anonymisation [Termes IGN] classification barycentrique [Termes IGN] espace euclidien [Termes IGN] graphe [Termes IGN] positionnement en intérieur [Termes IGN] protection de la vie privée [Termes IGN] service fondé sur la position Résumé : (auteur) With the expansion of wireless-communication infrastructure and the evolution of indoor positioning technologies, the demand for location-based services (LBS) has been increasing in indoor as well as outdoor spaces. However, we should consider a significant challenge regarding the location privacy for realizing indoor LBS. To avoid violations of location privacy, much research has been performed, and location K-anonymity has been intensively studied to blur a user location with a cloaking region involving at least K−1 locations of other persons. Owing to the differences between indoor and outdoor spaces, it is, however, difficult to apply this approach directly in an indoor space. First, the definition of the distance metric in indoor space is different from that in Euclidean and road-network spaces. Second, a bounding region, which is a general form of an anonymizing spatial region (ASR) in Euclidean space, does not respect the locality property in indoor space, where movement is constrained by building components. Therefore, we introduce the concept of indoor location K-anonymity in this paper. Then, we investigate the requirements of ASR in indoor spaces and propose novel methods to determine the ASR, considering hierarchical structures of the indoor space. While indoor ASRs are determined at the anonymizer, we also propose processing methods for r-range queries and k-nearest-neighbor queries at a location-based service provider. We validate our methods with experimental analysis of query-processing performance and resilience against attacks in indoor spaces. Numéro de notice : A2016-377 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-015-0241-y En ligne : http://dx.doi.org/10.1007/s10707-015-0241-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81144 [article]

The direction-constrained k nearest neighbor query dealing with spatio-directional objects / Min-Joong Lee in Geoinformatica, vol 20 n° 3 (July - September 2016)  

Public [article]  inGeoinformatica > vol 20 n° 3 (July - September 2016) . - pp 471 – 502 Titre : The direction-constrained k nearest neighbor query dealing with spatio-directional objects Type de document : Article/Communication Auteurs : Min-Joong Lee, Auteur ; Dong-Wan Choi, Auteur ; SangYeon Kim, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 471 – 502 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] analyse coût-avantage [Termes IGN] classification barycentrique [Termes IGN] données massives [Termes IGN] index spatial [Termes IGN] objet géographique [Termes IGN] plus proche voisin, algorithme du [Termes IGN] requête spatiale Résumé : (auteur) Finding k nearest neighbor objects in spatial databases is a fundamental problem in many geospatial systems and the direction is one of the key features of a spatial object. Moreover, the recent tremendous growth of sensor technologies in mobile devices produces an enormous amount of spatio-directional (i.e., spatially and directionally encoded) objects such as photos. Therefore, an efficient and proper utilization of the direction feature is a new challenge. Inspired by this issue and the traditional k nearest neighbor search problem, we devise a new type of query, called the direction-constrained k nearest neighbor (DCkNN) query. The DCkNN query finds k nearest neighbors from the location of the query such that the direction of each neighbor is in a certain range from the direction of the query. We develop a new index structure called MULTI, to efficiently answer the DCkNN query with two novel index access algorithms based on the cost analysis. Furthermore, our problem and solution can be generalized to deal with spatio-circulant dimensional (such as a direction and circulant periods of time such as an hour, a day, and a week) objects. Experimental results show that our proposed index structure and access algorithms outperform two adapted algorithms from existing kNN algorithms. Numéro de notice : A2016-378 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-016-0245-2 En ligne : http://dx.doi.org/10.1007/s10707-016-0245-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81145 [article]

Geographically weighted evidence combination approaches for combining discordant and inconsistent volunteered geographical information / Alexis Comber in Geoinformatica, vol 20 n° 3 (July - September 2016)  

Public [article]  inGeoinformatica > vol 20 n° 3 (July - September 2016) . - pp 503 – 527 Titre : Geographically weighted evidence combination approaches for combining discordant and inconsistent volunteered geographical information Type de document : Article/Communication Auteurs : Alexis Comber, Auteur ; Cidália Costa Fonte, Auteur ; Giles M. Foody, Auteur ; Ana-Maria Olteanu-Raimond , Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 503 – 527 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes IGN] analyse combinatoire (maths) [Termes IGN] classification bayesienne [Termes IGN] classification de Dempster-Shafer [Termes IGN] classification floue [Termes IGN] données localisées des bénévoles [Termes IGN] données multisources [Termes IGN] incertitude des données [Termes IGN] occupation du sol [Termes IGN] pondération [Termes IGN] qualité des données [Termes IGN] régression géographiquement pondérée [Termes IGN] Wikimapia Résumé : (auteur) There is much interest in being able to combine crowdsourced data. One of the critical issues in information sciences is how to combine data or information that are discordant or inconsistent in some way. Many previous approaches have taken a majority rules approach under the assumption that most people are correct most of the time. This paper analyses crowdsourced land cover data generated by the Geo-Wiki initiative in order to infer the land cover present at locations on a 50 km grid. It compares four evidence combination approaches (Dempster-Shafer, Bayes, Fuzzy Sets and Possibility) applied under a geographically weighted kernel with the geographically weighted average approach applied in many current Geo-Wiki analyses. A geographically weighted approach uses a moving kernel under which local analyses are undertaken. The contribution (or salience) of each data point to the analysis is weighted by its distance to the kernel centre, reflecting Tobler’s 1st law of geography. A series of analyses were undertaken using different kernel sizes (or bandwidths). Each of the geographically weighted evidence combination methods generated spatially distributed measures of belief in hypotheses associated with the presence of individual land cover classes at each location on the grid. These were compared with GlobCover, a global land cover product. The results from the geographically weighted average approach in general had higher correspondence with the reference data and this increased with bandwidth. However, for some classes other evidence combination approaches had higher correspondences possibly because of greater ambiguity over class conceptualisations and / or lower densities of crowdsourced data. The outputs also allowed the beliefs in each class to be mapped. The differences in the soft and the crisp maps are clearly associated with the logics of each evidence combination approach and of course the different questions that they ask of the data. The results show that discordant data can be combined (rather than being removed from analysis) and that data integrated in this way can be parameterised by different measures of belief uncertainty. The discussion highlights a number of critical areas for future research. Numéro de notice : A2016-379 Affiliation des auteurs : LASTIG COGIT+Ext (2012-2019) Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10707-016-0248-z Date de publication en ligne : 27/02/2016 En ligne : http://dx.doi.org/ 10.1007/s10707-016-0248-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81146 [article]

Task selection in spatial crowdsourcing from worker’s perspective / Dingxiong Deng in Geoinformatica, vol 20 n° 3 (July - September 2016)  

Public [article]  inGeoinformatica > vol 20 n° 3 (July - September 2016) . - pp 529 – 568 Titre : Task selection in spatial crowdsourcing from worker’s perspective Type de document : Article/Communication Auteurs : Dingxiong Deng, Auteur ; Cyrus Shahabi, Auteur ; Ugur Demiryurek, Auteur ; Linhong Zhu, Auteur Année de publication : 2016 Article en page(s) : pp 529 – 568 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes IGN] appareil portable [Termes IGN] approximation [Termes IGN] données localisées des bénévoles [Termes IGN] données spatiotemporelles [Termes IGN] géopositionnement [Termes IGN] ordonnancement de tâches [Termes IGN] programmation dynamique [Termes IGN] prospective [Termes IGN] téléphonie mobile [Termes IGN] travail coopératif Résumé : (auteur) With the progress of mobile devices and wireless broadband, a new eMarket platform, termed spatial crowdsourcing is emerging, which enables workers (aka crowd) to perform a set of spatial tasks (i.e., tasks related to a geographical location and time) posted by a requester. In this paper, we study a version of the spatial crowdsourcing problem in which the workers autonomously select their tasks, called the worker selected tasks (WST) mode. Towards this end, given a worker, and a set of tasks each of which is associated with a location and an expiration time, we aim to find a schedule for the worker that maximizes the number of performed tasks. We first prove that this problem is NP-hard. Subsequently, for small number of tasks, we propose two exact algorithms based on dynamic programming and branch-and-bound strategies. Since the exact algorithms cannot scale for large number of tasks and/or limited amount of resources on mobile platforms, we propose different approximation algorithms. Finally, to strike a compromise between efficiency and accuracy, we present a progressive algorithms. We conducted a thorough experimental evaluation with both real-world and synthetic data on desktop and mobile platforms to compare the performance and accuracy of our proposed approaches. Numéro de notice : A2016-380 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-016-0251-4 En ligne : http://dx.doi.org/10.1007/s10707-016-0251-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81147 [article]