Descripteur
Documents disponibles dans cette catégorie (45)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Etendre la recherche sur niveau(x) vers le bas
Spatial chromatic model in high-dimensional spaces and the uniqueness of chromatic code: a new perspective of geographic entity–space relationship / Weining Zhu in International journal of geographical information science IJGIS, vol 29 n° 1 (January 2015)
[article]
Titre : Spatial chromatic model in high-dimensional spaces and the uniqueness of chromatic code: a new perspective of geographic entity–space relationship Type de document : Article/Communication Auteurs : Weining Zhu, Auteur Année de publication : 2015 Article en page(s) : pp 28 - 45 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications SIG
[Termes IGN] espace objet
[Termes IGN] hétérogénéité spatiale
[Termes IGN] modèle entité-association
[Termes IGN] mosaïquage d'images
[Termes IGN] tessellationRésumé : (Auteur) The abstraction, representation, and computation of entity–space relationship are keystones of geographic information science (GIS). The newly proposed spatial chromatic tessellation (SCT) provides a novel model to explore this relationship. SCT has demonstrated a variety of potential applications in GIS, such as reasoning spatial topology, point pattern analysis, and Voronoi diagrams. This study aims to theoretically investigate SCT by focusing on two aspects: (1) extending SCT to higher dimensional spaces. Results show that cells missing in lower dimensional spaces are hidden in higher dimensional spaces; (2) exploring the uniqueness of chromatic codes, particularly the chromatic codes of 2-cell and 3-cell clusters: their codes are proved to be unique. In a mathematical perspective, the observed phenomena from the above two aspects bring some new thoughts into the first law of geography and spatial heterogeneity. Based on these new understandings of entity–space relationship, SCT is replaced by spatial chromatic model (SCM) in which spaces are created by entities themselves rather than by partitioning the space preexisted. This makes a change from an absolute geographic space to a relative geographic space. Numéro de notice : A2015-574 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2014.931586 En ligne : http://www.tandfonline.com/doi/full/10.1080/13658816.2014.931586 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77836
in International journal of geographical information science IJGIS > vol 29 n° 1 (January 2015) . - pp 28 - 45[article]Multi-UAV surveillance over forested regions / Vengatesan Govindaraju in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 12 (December 2014)
[article]
Titre : Multi-UAV surveillance over forested regions Type de document : Article/Communication Auteurs : Vengatesan Govindaraju, Auteur ; Gerard Leng, Auteur ; Zhang Qian, Auteur Année de publication : 2014 Article en page(s) : pp 1129 - 1137 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] couvert forestier
[Termes IGN] diagramme de Voronoï
[Termes IGN] drone
[Termes IGN] point d'appui
[Termes IGN] rayonnement incident
[Termes IGN] relief
[Termes IGN] simulation 3D
[Termes IGN] tessellationRésumé : (auteur) S-UAVs (Small-Unmanned Aerial Vehicles) have emerged as low-cost alternatives for aerial surveillance over forests. However, they provide limited coverage owing to their low altitudes and short endurance. Therefore, a quick and effective surveillance necessitates optimal flying paths, maximizing ground visibility. Even though the occlusion of ground points due to vegetation is significant in forests, it is generally neglected. This paper proposes a probabilistic sensing model that incorporates both occlusions due to terrain and vegetation, in the visibility computations and presents a two-step approach to determine near-optimal flight paths: (a) waypoints are strategically deployed to enhance visibility, using centroidal Voronoi tessellation, and (b) flyable paths are designed using a clustered spiral-alternating algorithm. Simulation studies conducted on synthetic terrains and a reconstructed terrain, from satellite data of tree-cover and a Digital Elevation Model (DEM), show the effectiveness of the proposed method in improving the terrain visibility as compared to commonly used grid-based waypoints. Numéro de notice : A2014-669 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.80.12.1129 En ligne : https://doi.org/10.14358/PERS.80.12.1129 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75128
in Photogrammetric Engineering & Remote Sensing, PERS > vol 80 n° 12 (December 2014) . - pp 1129 - 1137[article]A triangular form-based multiple flow algorithm to estimate overland flow distribution and accumulation on a digital elevation model / Petter Pilesjö in Transactions in GIS, vol 18 n° 1 (February 2014)
[article]
Titre : A triangular form-based multiple flow algorithm to estimate overland flow distribution and accumulation on a digital elevation model Type de document : Article/Communication Auteurs : Petter Pilesjö, Auteur ; Abdulghani Hasan, Auteur Année de publication : 2014 Article en page(s) : pp 108 - 124 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] données maillées
[Termes IGN] flux
[Termes IGN] maillage par triangles
[Termes IGN] maille triangulaire
[Termes IGN] modèle numérique de surface
[Termes IGN] tessellationRésumé : (Auteur) In this study, we present a newly developed method for the estimation of surface flow paths on a digital elevation model (DEM). The objective is to use a form-based algorithm, analyzing flow over single cells by dividing them into eight triangular facets and to estimate the surface flow paths on a raster DEM. For each cell on a gridded DEM, the triangular form-based multiple flow algorithm (TFM) was used to distribute flow to one or more of the eight neighbor cells, which determined the flow paths over the DEM. Because each of the eight facets covering a cell has a constant slope and aspect, the estimations of – for example – flow direction and divergence/convergence are more intuitive and less complicated than many traditional raster-based solutions. Experiments were undertaken by estimating the specific catchment area (SCA) over a number of mathematical surfaces, as well as on a real-world DEM. Comparisons were made between the derived SCA by the TFM algorithm with eight other algorithms reported in the literature. The results show that the TFM algorithm produced the closest outcomes to the theoretical values of the SCA compared with other algorithms, derived more consistent outcomes, and was less influenced by surface shapes. The real-world DEM test shows that the TFM was capable of modeling flow distribution without noticeable ‘artefacts’, and its ability to track flow paths makes it an appropriate platform for dynamic surface flow simulation. Numéro de notice : A2014-067 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12015 Date de publication en ligne : 06/02/2013 En ligne : https://doi.org/10.1111/tgis.12015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32972
in Transactions in GIS > vol 18 n° 1 (February 2014) . - pp 108 - 124[article]Scale-specific automated line simplification by vertex clustering on a hexagonal tessellation / Paulo Raposo in Cartography and Geographic Information Science, vol 40 n° 5 (November 2013)
[article]
Titre : Scale-specific automated line simplification by vertex clustering on a hexagonal tessellation Type de document : Article/Communication Auteurs : Paulo Raposo, Auteur Année de publication : 2013 Article en page(s) : pp 427 - 443 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées
[Termes IGN] analyse de groupement
[Termes IGN] distance de Hausdorff
[Termes IGN] généralisation cartographique automatisée
[Termes IGN] noeud
[Termes IGN] simplification de contour
[Termes IGN] tessellationRésumé : (Auteur) A new method of cartographic line simplification is presented. Regular hexagonal tessellations are used to sample lines for simplification, where hexagon width, reflecting sampling fidelity, is varied in proportion to target scale and drawing resolution. Tesserae constitute loci at which new sets of vertices are defined by vertex clustering quantization, and these vertices are used to compose simplified lines retaining only visually resolvable detail at target scale. Hexagon scaling is informed by the Nyquist–Shannon sampling theorem. The hexagonal quantization algorithm is also compared to an implementation of the Li–Openshaw raster-vector algorithm, which undertakes a similar process using square raster cells. Lines produced by either algorithm using like tessera widths are compared for fidelity to the original line in two ways: Hausdorff distances to the original lines are statistically analyzed, and simplified lines are presented against input lines for visual inspection. Results show that hexagonal quantization offers advantages over square tessellations for vertex clustering line simplification in that simplified lines are significantly less displaced from input lines. Visual inspection suggests lines produced by hexagonal quantization retain informative geographical shapes for greater differences in scale than do those produced by quantization in square cells. This study yields a scale-specific cartographic line simplification algorithm, following Li and Openshaw's natural principle, which is readily applicable to cartographic linework. Open-source Java code implementing the hexagonal quantization algorithm is available online. Numéro de notice : A2013-764 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1080/15230406.2013.803707 En ligne : https://doi.org/10.1080/15230406.2013.803707 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32900
in Cartography and Geographic Information Science > vol 40 n° 5 (November 2013) . - pp 427 - 443[article]Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 032-2013051 RAB Revue Centre de documentation En réserve L003 Disponible Multi-view dense matching supported by triangular meshes / D. Butalov in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 6 (November 2011)
[article]
Titre : Multi-view dense matching supported by triangular meshes Type de document : Article/Communication Auteurs : D. Butalov, Auteur ; P. Wernerus, Auteur ; Christian Heipke, Auteur Année de publication : 2011 Article en page(s) : pp 907 - 918 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] appariement d'images
[Termes IGN] appariement dense
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] maillage par triangles
[Termes IGN] précision infrapixellaire
[Termes IGN] reconstruction 3D
[Termes IGN] semis de points
[Termes IGN] séquence d'images
[Termes IGN] tessellationRésumé : (Auteur) We present a new procedure to compute dense 3D point clouds from a sequential set of images. This procedure is considered as a second step of a three-step algorithm for 3D reconstruction from image sequences, whose first step consists of image orientation and the last step is shape reconstruction. We assume that the camera matrices as well as a sparse set of 3D points are available and we strive for obtaining a dense and reliable 3D point cloud. Three novel ideas are presented: (1) for sparse tracking and triangulation, the search space for correspondences is reduced to a line segment by means of known camera matrices and disparity ranges are provided by triangular meshes from the already available points; (2) triangular meshes from extended sets of points are used for dense matching, because these meshes help to reconstruct points in weakly textured areas and present a natural way to obtain subpixel accuracy; (3) two non-local optimization methods, namely, 1D dynamic programming along horizontal lines and semi-global optimization were employed for refinement of local results obtained from an arbitrary number of images. All methods were extensively tested on a benchmark data set and an infrared video sequence. Both visual and quantitative results demonstrate the effectiveness of our algorithm. Numéro de notice : A2011-475 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.06.006 En ligne : https://doi.org/10.1016/j.isprsjprs.2011.06.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31369
in ISPRS Journal of photogrammetry and remote sensing > vol 66 n° 6 (November 2011) . - pp 907 - 918[article]Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2011061 SL Revue Centre de documentation Revues en salle Disponible Obtaining high fidelity triangular Regular Network from only DEM points / T. Gökgöz in Cartographic journal (the), vol 47 n° 2 (May 2010)PermalinkPermalinkDeveloping an adaptive topological tessellation for 3D modeling in geosciences / L. Hashemi Beni in Geomatica, vol 63 n° 4 (December 2009)PermalinkFinding anomalies in high-density Lidar point clouds / J. Harrison in Geomatica, vol 63 n° 4 (December 2009)PermalinkDynamic hybrid terrain representation based on convexity limits identification / M. Bóo in International journal of geographical information science IJGIS, vol 23 n°3-4 (march - april 2009)PermalinkOrthophoto generation from unorganized point clouds / L. Tournas in Photogrammetric Engineering & Remote Sensing, PERS, vol 73 n° 11 (November 2007)PermalinkUnified hybrid terrain representation based on local convexifications / M. Bóo in Geoinformatica, vol 11 n° 3 (September - November 2007)PermalinkAccuracy of quantized Voronoi diagrams / Yukio Sadahiro in International journal of geographical information science IJGIS, vol 20 n° 10 (november 2006)PermalinkMethod for detecting apparent differences between spatial tessellations at different time points / A. Masuyama in International journal of geographical information science IJGIS, vol 20 n° 6 (july 2006)PermalinkPermalink