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Uncertain Voronoi cell computation based on space decomposition / Klaus Arthur Schmid in Geoinformatica, vol 21 n° 4 (October - December 2017)
[article]
Titre : Uncertain Voronoi cell computation based on space decomposition Type de document : Article/Communication Auteurs : Klaus Arthur Schmid, Auteur ; Andreas Züfle, Auteur ; Tobias Emrich, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 763 -795 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] décomposition spatiale
[Termes IGN] diagramme de Voronoï
[Termes IGN] incertitude des données
[Termes IGN] plus proche voisin, algorithme du
[Termes IGN] traitement parallèleRésumé : (Auteur) To facilitate (k)-Nearest Neighbor queries, the concept of Voronoi decomposition is widely used. In this work, we propose solutions to extend the concept of Voronoi-cells to uncertain data. Due to data uncertainty, the location, the shape and the extent of a Voronoi cell are random variables. To facilitate reliable query processing despite the presence of uncertainty, we employ the concept of possible-Voronoi cells and introduce the novel concept of guaranteed-Voronoi cells: The possible-Voronoi cell of an object U consists of all points in space that have a non-zero probability of having U as their nearest-neighbor; and the guaranteed-Voronoi cell, which consists of all points in space which must have U as their nearest-neighbor. Since exact computation of both types of Voronoi cells is computationally hard, we propose approximate solutions. Therefore, we employ hierarchical access methods for both data and object space. Our proposed algorithm descends both index structures simultaneously, constantly trying to prune branches in both trees by employing the concept of spatial domination. To support (k)-Nearest Neighbor queries having k > 1, this work further pioneers solutions towards the computation of higher-order possible and higher-order guaranteed Voronoi cells, which consist of all points in space which may (respectively must) have U as one of their k-nearest neighbors. For this purpose, we develop three algorithms to explore our index structures and show that the approach that descends both index structures in parallel yields the fastest query processing times. Our experiments show that we are able to approximate uncertain Voronoi cells of any order much more effectively than the state-of-the-art while improving run-time performance. Since our approach is the first to compute guaranteed-Voronoi cells and higher order (possible and guaranteed) Voronoi cells, we extend the existing state-of-the-art solutions to these concepts, in order to allow a fair experimental evaluation. Numéro de notice : A2017-604 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-017-0293-2 En ligne : https://doi.org/10.1007/s10707-017-0293-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86913
in Geoinformatica > vol 21 n° 4 (October - December 2017) . - pp 763 -795[article]Visual analytics of delays and interaction in movement data / Maximilian Konzack in International journal of geographical information science IJGIS, vol 31 n° 1-2 (January - February 2017)
[article]
Titre : Visual analytics of delays and interaction in movement data Type de document : Article/Communication Auteurs : Maximilian Konzack, Auteur ; Thomas McKetterick, Auteur ; Tim Ophelder, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 320 - 345 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse géovisuelle
[Termes IGN] décomposition spatiale
[Termes IGN] distance de Fréchet
[Termes IGN] données spatiotemporelles
[Termes IGN] navigation
[Termes IGN] objet mobile
[Vedettes matières IGN] GéovisualisationRésumé : (auteur) The analysis of interaction between movement trajectories is of interest for various domains when movement of multiple objects is concerned. Interaction often includes a delayed response, making it difficult to detect interaction with current methods that compare movement at specific time intervals. We propose analyses and visualizations, on a local and global scale, of delayed movement responses, where an action is followed by a reaction over time, on trajectories recorded simultaneously. We developed a novel approach to compute the global delay in subquadratic time using a fast Fourier transform (FFT). Central to our local analysis of delays is the computation of a matching between the trajectories in a so-called delay space. It encodes the similarities between all pairs of points of the trajectories. In the visualization, the edges of the matching are bundled into patches, such that shape and color of a patch help to encode changes in an interaction pattern. To evaluate our approach experimentally, we have implemented it as a prototype visual analytics tool and have applied the tool on three bidimensional data sets. For this we used various measures to compute the delay space, including the directional distance, a new similarity measure, which captures more complex interactions by combining directional and spatial characteristics. We compare matchings of various methods computing similarity between trajectories. We also compare various procedures to compute the matching in the delay space, specifically the Fréchet distance, dynamic time warping (DTW), and edit distance (ED). Finally, we demonstrate how to validate the consistency of pairwise matchings by computing matchings between more than two trajectories. Numéro de notice : A2017-034 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2016.1199806 En ligne : http://dx.doi.org/10.1080/13658816.2016.1199806 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84027
in International journal of geographical information science IJGIS > vol 31 n° 1-2 (January - February 2017) . - pp 320 - 345[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 079-2017011 RAB Revue Centre de documentation En réserve L003 Disponible 079-2017012 RAB Revue Centre de documentation En réserve L003 Disponible Hyperspectral image noise reduction based on rank-1 tensor decomposition / Xian Guoa in ISPRS Journal of photogrammetry and remote sensing, vol 83 (September 2013)
[article]
Titre : Hyperspectral image noise reduction based on rank-1 tensor decomposition Type de document : Article/Communication Auteurs : Xian Guoa, Auteur ; Xian Guo, Auteur ; Xin Huang, Auteur ; Liangpei Zhanga, Auteur ; Lefei Zhang, Auteur Année de publication : 2013 Article en page(s) : pp 50 - 63 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] calcul tensoriel
[Termes IGN] décomposition spatiale
[Termes IGN] filtrage du bruit
[Termes IGN] image hyperspectrale
[Termes IGN] tenseur
[Termes IGN] valeur propre
[Termes IGN] voxelRésumé : (Auteur) In this study, a novel noise reduction algorithm for hyperspectral imagery (HSI) is proposed based on high-order rank-1 tensor decomposition. The hyperspectral data cube is considered as a three-order tensor that is able to jointly treat both the spatial and spectral modes. Subsequently, the rank-1 tensor decomposition (R1TD) algorithm is applied to the tensor data, which takes into account both the spatial and spectral information of the hyperspectral data cube. A noise-reduced hyperspectral image is then obtained by combining the rank-1 tensors using an eigenvalue intensity sorting and reconstruction technique. Compared with the existing noise reduction methods such as the conventional channel-by-channel approaches and the recently developed multidimensional filter, the spatial–spectral adaptive total variation filter, experiments with both synthetic noisy data and real HSI data reveal that the proposed R1TD algorithm significantly improves the HSI data quality in terms of both visual inspection and image quality indices. The subsequent image classification results further validate the effectiveness of the proposed HSI noise reduction algorithm. Numéro de notice : A2013-488 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.06.001 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.06.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32626
in ISPRS Journal of photogrammetry and remote sensing > vol 83 (September 2013) . - pp 50 - 63[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2013091 RAB Revue Centre de documentation En réserve L003 Disponible Developing an adaptive topological tessellation for 3D modeling in geosciences / L. Hashemi Beni in Geomatica, vol 63 n° 4 (December 2009)
[article]
Titre : Developing an adaptive topological tessellation for 3D modeling in geosciences Type de document : Article/Communication Auteurs : L. Hashemi Beni, Auteur ; Mir Abolfazl Mostafavi, Auteur ; Jacynthe Pouliot, Auteur ; R. Therrien, Auteur Année de publication : 2009 Article en page(s) : pp 419 - 431 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse mathématique
[Termes IGN] décomposition spatiale
[Termes IGN] diagramme de Voronoï
[Termes IGN] modélisation 3D
[Termes IGN] tessellation
[Termes IGN] triangulation de DelaunayRésumé : (Auteur) La valeur des systèmes d'information géographique (SIG) est grandement connue pour un ensemble d'applications géoscientifiques variant de la gestion des ressources en eau à l'étude des répercussions du réchauffement planétaire. Les SIG fournissent aux géoscientifiques des plates-formes de calcul rigoureuses pour la gestion, la visualisation, les requêtes, l'intégration et l'analyse des données spatiales. Toutefois, la représentation et la gestion des phénomènes géoscientifiques qui sont généralement tridimensionnels et hétérogènes exigent une tessellation spatiale optimale en 3-D. Une tessellation optimale est caractérisée par des éléments bien modélisés et bien espacés qui fournissent une représentation exacte de l'information topologique et géométrique. Dans le présent article, nous discutons des limites des méthodes de tessellation spatiale tridimensionnelle actuelles qui sont utilisées pour la modélisation géologique 3-D, l'interpolation 3-D, les simulations de l'écoulement des fluides 3-D, entre autres. Ensuite, nous proposons un algorithme de raffinement automatique basé sur la tétraédralisation de Delaunay et ses opérations dynamiques. Enfin, nous présentons et discutons des résultats et du rendement de l'algorithme. Copyright Geomatica Numéro de notice : A2009-557 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE Nature : Article DOI : 10.5623/geomat-2009-0054 En ligne : https://cdnsciencepub.com/doi/abs/10.5623/geomat-2009-0054 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30186
in Geomatica > vol 63 n° 4 (December 2009) . - pp 419 - 431[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 035-09041 RAB Revue Centre de documentation En réserve L003 Disponible An efficient domain decomposition framework for accurate representation of geodata in distributed hydrologic models / Muneendra Kumar in International journal of geographical information science IJGIS, vol 23 n°11-12 (november 2009)
[article]
Titre : An efficient domain decomposition framework for accurate representation of geodata in distributed hydrologic models Type de document : Article/Communication Auteurs : Muneendra Kumar, Auteur ; G. Bahtt, Auteur ; C. Duffy, Auteur Année de publication : 2009 Article en page(s) : pp 1569 - 1596 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] décomposition spatiale
[Termes IGN] hydrogéologie
[Termes IGN] hydrographie de surface
[Termes IGN] modèle hydrographique
[Termes IGN] objet géographique
[Termes IGN] visualisation de données
[Vedettes matières IGN] GéovisualisationRésumé : (Auteur) Physically-based, fully-distributed hydrologic models simulate hydrologic state variables in space and time while using information regarding heterogeneity in climate, land use, topography and hydrogeology. Since fine spatio-temporal resolution and increased process dimension will have large data requirements, there is a practical need to strike a balance between descriptive detail and computational load for a particular model application. In this paper, we present a flexible domain decomposition strategy for efficient and accurate integration of the physiographic, climatic and hydrographic watershed features. The approach takes advantage of different GIS feature types while generating high-quality unstructured grids with user-specified geometrical and physical constraints. The framework is able to anchor the efficient capture of spatially distributed and temporally varying hydrologic interactions and also ingest the physical prototypes effectively and accurately from a geodatabase. The proposed decomposition framework is a critical step in implementing high quality, multiscale, multiresolution, temporally adaptive and nested grids with least computational burden. We also discuss the algorithms for generating the framework using existing GIS feature objects. The framework is successfully being used in a finite volume based integrated hydrologic model. The framework is generic and can be used in other finite element/volume based hydrologic models. Copyright Taylor & Francis Numéro de notice : A2009-521 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810802344143 En ligne : https://doi.org/10.1080/13658810802344143 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30150
in International journal of geographical information science IJGIS > vol 23 n°11-12 (november 2009) . - pp 1569 - 1596[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 079-09071 RAB Revue Centre de documentation En réserve L003 Disponible 079-09072 RAB Revue Centre de documentation En réserve L003 Disponible An introduction to solid modeling / Martti Mantyla (1988)Permalink