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Stacked space-time densities: a geovisualisation approach to explore dynamics of space use over time / Urška Demšar in Geoinformatica, vol 19 n° 1 (January - March 2015)
[article]
Titre : Stacked space-time densities: a geovisualisation approach to explore dynamics of space use over time Type de document : Article/Communication Auteurs : Urška Demšar, Auteur ; Kevin Buchin, Auteur ; E. Emiel Van Loon, Auteur ; Judy Shamoun-Baranes, Auteur Année de publication : 2015 Article en page(s) : pp 85 - 115 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] agrégation spatiale
[Termes IGN] agrégation temporelle
[Termes IGN] analyse spatio-temporelle
[Termes IGN] Aves
[Termes IGN] cube espace-temps
[Termes IGN] densité
[Termes IGN] distance de propagation
[Termes IGN] données spatiotemporelles
[Termes IGN] estimation par noyau
[Termes IGN] migration animale
[Termes IGN] positionnement cinématique
[Vedettes matières IGN] GéovisualisationRésumé : (auteur) Recent developments and ubiquitous use of global positioning devices have revolutionised movement ecology. Scientists are able to collect increasingly larger movement datasets at increasingly smaller spatial and temporal resolutions. These data consist of trajectories in space and time, represented as time series of measured locations for each tagged animal. Such data are analysed and visualised using methods for estimation of home range or utilisation distribution, which are often based on 2D kernel density in geographic space. These methods have been developed for much sparser and smaller datasets obtained through very high frequency (VHF) radio telemetry. They focus on the spatial distribution of measurement locations and ignore time and sequentiality of measurements. We present an alternative geovisualisation method for spatio-temporal aggregation of trajectories of tagged animals: stacked space-time densities. The method was developed to visually portray temporal changes in animal use of space using a volumetric display in a space-time cube. We describe the algorithm for calculation of stacked densities using four different decay functions, normally used in space use studies: linear decay, bisquare decay, Gaussian decay and Brownian decay. We present a case study, where we visualise trajectories of lesser black backed gulls, collected over 30 days. We demonstrate how the method can be used to evaluate temporal site fidelity of each bird through identification of two different temporal movement patterns in the stacked density volume: spatio-temporal hot spots and spatial-only hot spots. Numéro de notice : A2015-486 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-014-0207-5 Date de publication en ligne : 03/04/2014 En ligne : https://doi.org/10.1007/s10707-014-0207-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77249
in Geoinformatica > vol 19 n° 1 (January - March 2015) . - pp 85 - 115[article]Detecting and analyzing mobility hotspots using surface networks / Y. Hu in Transactions in GIS, vol 18 n° 6 (December 2014)
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Titre : Detecting and analyzing mobility hotspots using surface networks Type de document : Article/Communication Auteurs : Y. Hu, Auteur ; Harvey J. Miller, Auteur ; X. Li, Auteur Année de publication : 2014 Article en page(s) : pp 911 – 935 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] estimation par noyau
[Termes IGN] mobilité humaine
[Termes IGN] objet mobile
[Termes IGN] Shanghai (Chine)
[Termes IGN] théorie des graphes
[Termes IGN] topologieRésumé : (Auteur) Capabilities for collecting and storing data on mobile objects have increased dramatically over the past few decades. A persistent difficulty is summarizing large collections of mobile objects. This article develops methods for extracting and analyzing hotspots or locations with relatively high levels of mobility activity. We use kernel density estimation (KDE) to convert a large collection of mobile objects into a smooth, continuous surface. We then develop a topological algorithm to extract critical geometric features of the surface; these include critical points (peaks, pits and passes) and critical lines (ridgelines and course-lines). We connect the peaks and corresponding ridgelines to produce a surface network that summarizes the topological structure of the surface. We apply graph theoretic indices to analytically characterize the surface and its changes over time. To illustrate our approach, we apply the techniques to taxi cab data collected in Shanghai, China. We find increases in the complexity of the hotspot spatial distribution during normal activity hours in the late morning, afternoon and evening and a spike in the connectivity of the hotspot spatial distribution in the morning as taxis concentrate on servicing travel to work. These results match with scientific and anecdotal knowledge about human activity patterns in the study area. Numéro de notice : A2014-577 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12076 Date de publication en ligne : 17/02/2014 En ligne : https://doi.org/10.1111/tgis.12076 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74767
in Transactions in GIS > vol 18 n° 6 (December 2014) . - pp 911 – 935[article]Spatial analysis of coastal chalk cliff falls in upper Normandy (France). From Veules-les-Roses to Le Treport (2002-2009) / Pauline Letortu in Revue internationale de géomatique, vol 24 n° 3 (septembre - novembre 2014)
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Titre : Spatial analysis of coastal chalk cliff falls in upper Normandy (France). From Veules-les-Roses to Le Treport (2002-2009) Type de document : Article/Communication Auteurs : Pauline Letortu, Auteur ; Stéphane Costa, Auteur ; Emmanuel Bonnet, Auteur Année de publication : 2014 Article en page(s) : pp 335 - 354 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] base de données localisées
[Termes IGN] cartographie des risques
[Termes IGN] craie
[Termes IGN] données spatiotemporelles
[Termes IGN] éboulement
[Termes IGN] estimation par noyau
[Termes IGN] falaise
[Termes IGN] Haute-Normandie
[Termes IGN] inventaire
[Termes IGN] prévention des risquesRésumé : (Auteur) Coastal chalk cliff falls in Upper Normandy (France) are frequent and have specific spatial and temporal distributions. From 2002 to 2009, the ESTRAN organization (Scientific and Technical Space of Aquatic Resources and Navigation) conducted a weekly inventory of 331 cliff falls (location, volume, and date) between Veules-les-Roses and Le Treport (37.5 km). An amount of 331 falls was counted (date, location, measures of fall deposit). This database is remarkable because of the duration and high frequency of field surveys. The geographical and spatial statistics (locational analysis) methods used in this study aim to determine and understand the spatial and temporal distributions of coastal chalk cliff falls. Exhaustive cartography of such falls thus highlights the cap d’Ailly sector as being the most sensitive to an erosive dynamic along the coast from Veules-les-Roses to Le Treport. Furthermore, this cartography stresses many types of fall kinematics. This can be partly explained by lithological characteristics may predispose mass and particle movements. Using the combination of centrographic statistics, Ripley’s K-function, Besag’s L-function and kernel density, we have identified: 1) high cliff fall polarization at cap d’Ailly; 2) organization scales of fall locations per water year; 3) areas of massive and numerous falls (fall hazard areas). This information is essential for a better understanding of the working of the studied area and also for the set up of risk prevention tools. Numéro de notice : A2014-519 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.3166/rig.24.335-354 En ligne : https://doi.org/10.3166/rig.24.335-354 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74126
in Revue internationale de géomatique > vol 24 n° 3 (septembre - novembre 2014) . - pp 335 - 354[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 047-2014031 RAB Revue Centre de documentation En réserve L003 Disponible Studying commuting behaviours using collaborative visual analytics / Roger Beecham in Computers, Environment and Urban Systems, vol 47 (September 2014)
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Titre : Studying commuting behaviours using collaborative visual analytics Type de document : Article/Communication Auteurs : Roger Beecham, Auteur ; Jo Wood, Auteur ; Audrey Bowerman, Auteur Année de publication : 2014 Article en page(s) : pp 5 - 15 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse géovisuelle
[Termes IGN] analyse spatio-temporelle
[Termes IGN] cycliste
[Termes IGN] densité des points
[Termes IGN] estimation par noyau
[Termes IGN] Londres
[Termes IGN] migration pendulaire
[Termes IGN] mobilité urbaine
[Termes IGN] origine - destination
[Vedettes matières IGN] GéovisualisationRésumé : (auteur) Mining a large origin–destination dataset of journeys made through London’s Cycle Hire Scheme (LCHS), we develop a technique for automatically classifying commuting behaviour that involves a spatial analysis of cyclists’ journeys. We identify a subset of potential commuting cyclists, and for each individual define a plausible geographic area representing their workplace. All peak-time journeys terminating within the vicinity of this derived workplace in the morning, and originating from this derived workplace in the evening, we label commutes. Three techniques for creating these workplace areas are compared using visual analytics: a weighted mean-centres calculation, spatial k-means clustering and a kernel density-estimation method. Evaluating these techniques at the individual cyclist level, we find that commuters’ peak-time journeys are more spatially diverse than might be expected, and that for a significant portion of commuters there appears to be more than one plausible spatial workplace area. Evaluating the three techniques visually, we select the density-estimation as our preferred method. Two distinct types of commuting activity are identified: those taken by LCHS customers living outside of London, who make highly regular commuting journeys at London’s major rail hubs; and more varied commuting behaviours by those living very close to a bike-share docking station. We find evidence of many interpeak journeys around London’s universities apparently being taken as part of cyclists’ working day. Imbalances in the number of morning commutes to, and evening commutes from, derived workplaces are also found, which might relate to local availability of bikes. Significant decisions around our workplace analysis, and particularly these broader insights into commuting behaviours, are discovered through exploring this analysis visually. The visual analysis approach described in the paper is effective in enabling a research team with varying levels of analysis experience to participate in this research. We suggest that such an approach is of relevance to many applied research contexts. Numéro de notice : A2014-798 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/URBANISME Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.compenvurbsys.2013.10.007 En ligne : http://dx.doi.org/10.1016/j.compenvurbsys.2013.10.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82467
in Computers, Environment and Urban Systems > vol 47 (September 2014) . - pp 5 - 15[article]Mapping social activities and concepts with social media (Twitter) and web search engines (Yahoo and Bing): a case study in 2012 US Presidential Election / Ming-Hsiang Tsou in Cartography and Geographic Information Science, vol 40 n° 4 (September 2013)
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Titre : Mapping social activities and concepts with social media (Twitter) and web search engines (Yahoo and Bing): a case study in 2012 US Presidential Election Type de document : Article/Communication Auteurs : Ming-Hsiang Tsou, Auteur ; Jiue-An Yang, Auteur ; Brian Spitzberg, Auteur ; Jean Marc Gawron, Auteur ; Dipak Gupta, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 337 - 348 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] analyse diachronique
[Termes IGN] comportement
[Termes IGN] données issues des réseaux sociaux
[Termes IGN] élection
[Termes IGN] estimation par noyau
[Termes IGN] Etats-Unis
[Termes IGN] logiciel de navigation
[Termes IGN] moteur de recherche
[Termes IGN] ontologie
[Termes IGN] TwitterRésumé : (Auteur) We introduce a new research framework for analyzing the spatial distribution of web pages and social media (Twitter) messages with related contents, called Visualizing Information Space in Ontological Networks (VISION). This innovative method can facilitate the tracking of ideas and social events disseminated in cyberspace from a spatial-temporal perspective. Thousands of web pages and millions of tweets associated with the same keywords were converted into visualization maps using commercial web search engines (Yahoo application programming interface (API) and Bing API), a social media search engine (Twitter APIs), Internet Protocol (IP) geolocation methods, and Geographic Information Systems (GIS) functions (e.g., kernel density and raster-based map algebra methods). We found that comparing multiple web information landscapes with different keywords or different dates can reveal important spatial patterns and “geospatial fingerprints” for selected keywords. We used the 2012 US Presidential Election candidates as our case study to validate this method. We noticed that the weekly changes of the geographic probability of hosting “Barack Obama” or “Mitt Romney” web pages are highly related to certain major campaign events. Both attention levels and the content of the tweets were deeply impacted by Hurricane Sandy. This new approach may provide a new research direction for studying human thought, human behaviors, and social activities quantitatively. Numéro de notice : A2013-762 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/15230406.2013.799738 En ligne : https://doi.org/10.1080/15230406.2013.799738 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32898
in Cartography and Geographic Information Science > vol 40 n° 4 (September 2013) . - pp 337 - 348[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 032-2013041 RAB Revue Centre de documentation En réserve L003 Disponible Space-time density of trajectories : exploring spatio-temporal patterns in movement data / Urška Demšar in International journal of geographical information science IJGIS, vol 24 n° 10 (october 2010)PermalinkMulti-scale spatiotemporal analyses of moose-vehicle collisions: a case study in northern Vermont / Giorgos Mountrakis in International journal of geographical information science IJGIS, vol 23 n°11-12 (november 2009)PermalinkA kernel density estimation method for networks, its computational method and a GIS-based tool / Atsuyuki Okabe in International journal of geographical information science IJGIS, vol 23 n° 1-2 (january 2009)PermalinkSpatial aspects of MRSA epidemiology: a case study using stochastic simulation, kernel estimation and SaTScan / Lucy Bastin in International journal of geographical information science IJGIS, vol 21 n° 6-7 (july 2007)PermalinkMapping wildfire occurrence at regional scale / J. De La Riva in Remote sensing of environment, vol 92 n° 3 (30 August 2004)Permalink