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Road network structure and ride-sharing accessibility: A network science perspective / Mingshu Wang in Computers, Environment and Urban Systems, vol 80 (March 2020)
[article]
Titre : Road network structure and ride-sharing accessibility: A network science perspective Type de document : Article/Communication Auteurs : Mingshu Wang, Auteur ; Zheyan Chen, Auteur ; Lan Mu, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] Atlanta (Géorgie)
[Termes IGN] autopartage
[Termes IGN] densité de population
[Termes IGN] gestion urbaine
[Termes IGN] migration pendulaire
[Termes IGN] modèle conceptuel de données localisées
[Termes IGN] OpenStreetMap
[Termes IGN] réseau routier
[Termes IGN] système d'information géographiqueRésumé : (auteur) The prosperity of ride-sharing services has rippled in the communities of GIScience, transportation, and urban planning. Meanwhile, road network structure has been analyzed from a network science perspective that focuses on nodes and relational links and aims to predictive models. However, limited empirical studies have explored the relationship between road network structure and ride-sharing accessibility through such perspective. This paper utilizes the spatial Durbin model to understand the relationship between road network structure and ride-sharing accessibility, proxied by Uber accessibility, through classical network measures of degree, closeness, and betweenness centrality. Taking the city of Atlanta as a case study, we have found in addition to population density and road network density, larger values of degree centrality and smaller values of closeness centrality of the road network are associated with better accessibility of Uber services. However, the effects of betweenness centrality are not significant. Furthermore, we have revealed heterogeneous effects of degree centrality and closeness centrality on the accessibility of Uber services, as the magnitudes of their effects vary by different time windows (i.e., weekday vs. weekend, rush hour in the morning vs. evening). Network science provides us both conceptual and methodological measures to understand the association between road network structure and ride-sharing accessibility. In this study, we constructed road network structure measures with OpenStreetMap, which is reproducible, replicable, and scalable because of its global coverage and public availability. The study resonates with the notion of cities as the set of interactions across networks, as we have observed time-sensitive heterogeneous effects of road network structure on ride-sharing accessibility. Numéro de notice : A2020-190 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1016/j.compenvurbsys.2019.101430 Date de publication en ligne : 12/11/2019 En ligne : https://doi.org/10.1016/j.compenvurbsys.2019.101430 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94852
in Computers, Environment and Urban Systems > vol 80 (March 2020)[article]Revealing the Correlation between Population Density and the Spatial Distribution of Urban Public Service Facilities with Mobile Phone Data / Yi Shi in ISPRS International journal of geo-information, Vol 9 n° 1 (January 2020)
[article]
Titre : Revealing the Correlation between Population Density and the Spatial Distribution of Urban Public Service Facilities with Mobile Phone Data Type de document : Article/Communication Auteurs : Yi Shi, Auteur ; Junyan Yang, Auteur ; Peiyu Shen, Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] densité de population
[Termes IGN] distribution spatiale
[Termes IGN] données spatiotemporelles
[Termes IGN] occupation du sol
[Termes IGN] recensement démographique
[Termes IGN] service public
[Termes IGN] Shanghai (Chine)
[Termes IGN] téléphone intelligent
[Termes IGN] utilisation du sol
[Termes IGN] zone urbaineRésumé : (auteur) Some studies have confirmed the association between urban public services and population density; however, other studies using census data, for example, have arrived at the opposite conclusion. Mobile signaling data provide new technological tools to investigate the subject. Based on the data of 20 million 2G mobile phone users in downtown Shanghai and the land use data of urban public service facilities, this study explores the spatiotemporal correlation between population density and public service facilities’ locations in downtown Shanghai and its variation laws. The correlation between individual population density at day vs. night and urban public service facilities distribution was also examined from a dynamic perspective. The results show a correlation between service facilities’ locations and urban population density at different times of the day. As a result, the average population density observed over a long period of time (day-time periodicity or longer) with census data or remote sensing data does not directly correlation with the distribution of public service facilities despite its correlation with public service facilities distribution. Among them, there is a significant spatial correlation between public service facilities and daytime population density and a significant spatial correlation between non-public service facilities and night-time population density. The spatial and temporal changes in the relationship between urban population density and service facilities is due to changing crowd behavior; however, the density of specific types of behavior is the real factor that affects the layout of urban public service facilities. The results show that mobile signaling data and land use data of service facilities are of great value for studying the spatiotemporal correlations between urban population density and service facilities Numéro de notice : A2020-115 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/ijgi9010038 Date de publication en ligne : 13/01/2020 En ligne : https://doi.org/10.3390/ijgi9010038 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94725
in ISPRS International journal of geo-information > Vol 9 n° 1 (January 2020)[article]
Titre : Ensemble methods for pedestrian detection in dense crowds Type de document : Thèse/HDR Auteurs : Jennifer Vandoni, Auteur ; Sylvie Le Hégarat-Mascle, Directeur de thèse Editeur : Paris-Orsay : Université de Paris 11 Paris-Sud Centre d'Orsay Année de publication : 2019 Importance : 182 p. Format : 21 x 30 cm Note générale : bibliographie
Thèse de Doctorat de l'Université Paris-Saclay, Sciences et technologies de l’information et de la communication (STIC), Spécialité : Traitement du Signal et des ImagesLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] algorithme d'apprentissage
[Termes IGN] apprentissage dirigé
[Termes IGN] apprentissage profond
[Termes IGN] classification par réseau neuronal convolutif
[Termes IGN] classification par séparateurs à vaste marge
[Termes IGN] comportement
[Termes IGN] densité de population
[Termes IGN] détection de piéton
[Termes IGN] données multicapteurs
[Termes IGN] étalonnage
[Termes IGN] fusion de données
[Termes IGN] taxinomie
[Termes IGN] théorie de Dempster-ShaferIndex. décimale : THESE Thèses et HDR Résumé : (auteur) The interest surrounding the study of crowd phenomena spanned during the last decade across multiple fields, including computer vision, physics, sociology, simulation and visualization. There are different levels of granularity at which crowd studies can be performed, namely a finer microanalysis, aimed to detect and then track each pedestrian individually; and a coarser macro-analysis, aimed to model the crowd as a whole.
One of the most difficult challenges when working with human crowds is that usual pedestrian detection methodologies do not scale well to the case where only heads are visible, for a number of reasons such as absence of background, high visual homogeneity, small size of the objects, and heavy occlusions. For this reason, most micro-analysis studies by means of pedestrian detection and tracking methodologies are performed in low to medium-density crowds, whereas macro-analysis through density estimation and people counting is more suited in presence of high-density crowds, where the exact position of each individual is not necessary. Nevertheless, in order to analyze specific events involving high-density crowds for monitoring the flow and preventing disasters such as stampedes, a complete understanding of the scene must be reached. This study deals with pedestrian detection in high-density crowds from a monocamera system, striving to obtain localized detections of all the individuals which are part of an extremely dense crowd. The detections can be then used both to obtain robust density estimation, and to initialize a tracking algorithm. In presence of difficult problems such as our application, supervised learning techniques are well suited. However, two different questions arise, namely which classifier is the most adapted for the considered environment, and which data to use to learn from. We cast the detection problem as a Multiple Classifier System (MCS), composed by two different ensembles of classifiers, the first one based on SVM (SVM-ensemble) and the second one based on CNN (CNN-ensemble), combined relying on the Belief Function Theory (BFT) designing a fusion method which is able to exploit their strengths for pixel-wise classification. SVM-ensemble is composed by several SVM detectors based on different gradient, texture and orientation descriptors, able to tackle the problem from different perspectives. BFT allows us to take into account the imprecision in addition to the uncertainty value provided by each classifier, which we consider coming from possible errors in the calibration procedure and from pixel neighbor’s heterogeneity in the image space due to the close resolution of the target (head) and
descriptor respectively. However, scarcity of labeled data for specific dense crowd contexts reflects in the impossibility to easily obtain robust training and validation sets. By exploiting belief functions directly derived
from the classifiers’ combination, we therefore propose an evidential Query-by-Committee (QBC) active learning algorithm to automatically select the most informative training samples. On the other side, we explore deep learning techniques by casting the problem as a segmentation task in presence of soft labels, with a fully convolutional network architecture designed to recover small objects (heads) thanks to a tailored use of dilated convolutions. In order to obtain a pixel-wise measure of reliability about the network’s predictions, we create a CNN-ensemble by means of dropout at inference time, and we combine the different obtained realizations in the
context of BFT. To conclude, we show that the dense output map given by the MCS can be employed not only
for pedestrian detection at microscopic level, but also to perform macroscopic analysis, bridging the gap between the two levels of granularity. We therefore finally focus our attention to people counting, proposing an evaluation method that can be applied at every scale, resulting to be more precise in the error and uncertainty evaluation (disregarding possible compensations) as well as more useful for the modeling community that could use it to improve and validate local density estimation.Note de contenu : 1- Crowd understanding
2- Supervised learning and classifier combination
3- SVM descriptors for pedestrian detection in high-density crowds
4- Taking into account imprecision with Belief Function Framework
5- Evidential QBC Active Learning
6- CNNs for pedestrian detection in high-density crowds
7- CNN-ensemble and evidential Multiple Classifier System
8- Density Estimation
ConclusionNuméro de notice : 25704 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : Traitement du Signal et des Images : Paris 11 : 2019 Organisme de stage : Systèmes et applications des technologies de l'information et de l'énergie (Paris) nature-HAL : Thèse DOI : sans En ligne : https://theses.hal.science/tel-02318892/document Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94838 Testing time-geographic density estimation for home range analysis using an agent-based model of animal movement / Joni A. Downs in International journal of geographical information science IJGIS, vol 32 n° 7-8 (July - August 2018)
[article]
Titre : Testing time-geographic density estimation for home range analysis using an agent-based model of animal movement Type de document : Article/Communication Auteurs : Joni A. Downs, Auteur ; Mark Horner, Auteur ; David Lamb, Auteur ; Rebecca W. Loraamm, Auteur ; James Anderson, Auteur ; Brittany Wood, Auteur Année de publication : 2018 Article en page(s) : pp 1505 - 1522 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] aire naturelle (écologie)
[Termes IGN] densité de population
[Termes IGN] données localisées
[Termes IGN] méthode fondée sur le noyau
[Termes IGN] migration animale
[Termes IGN] modèle orienté agent
[Termes IGN] population animale
[Termes IGN] Time-geographyRésumé : (auteur) Time-geographic density estimation (TGDE) is a method of movement pattern analysis that generates a continuous intensity surface from a set of tracking data. TGDE has recently been proposed as a method of animal home range estimation, where the goal is to delineate the spatial extents that an animal occupies. This paper tests TGDE’s effectiveness as a home range estimator using simulated movement data. First, an agent-based model is used to simulate tracking data under 16 movement scenarios representing a variety of animal life history traits (habitat preferences, homing behaviour, mobility) and habitat configurations (levels of habitat fragmentation). Second, the accuracy of TGDE is evaluated for four temporal sampling frequencies using three adaptive velocity parameters for 30 sample data sets from each scenario. Third, TGDE accuracy is compared to two other common home range estimation methods, kernel density estimation (KDE) and characteristic hull polygons (CHP). The results demonstrate that TGDE is the most effective at estimating core areas, home ranges and total areas at high sampling frequencies, while CHP performs better at low sampling frequencies. KDE was ineffective across all scenarios explored. Numéro de notice : A2018-281 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658816.2017.1421764 Date de publication en ligne : 03/01/2018 En ligne : https://doi.org/10.1080/13658816.2017.1421764 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90363
in International journal of geographical information science IJGIS > vol 32 n° 7-8 (July - August 2018) . - pp 1505 - 1522[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 079-2018041 RAB Revue Centre de documentation En réserve L003 Disponible Vers une nouvelle approche pour calculer les indicateurs de la densité urbaine via l'imagerie de satellite Alsat-2A / Tarek Medjadj in Bulletin des sciences géographiques, n° 31 (2017 - 2018)
[article]
Titre : Vers une nouvelle approche pour calculer les indicateurs de la densité urbaine via l'imagerie de satellite Alsat-2A Type de document : Article/Communication Auteurs : Tarek Medjadj, Auteur ; M. Hadji, Auteur Année de publication : 2018 Article en page(s) : pp 46 - 53 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse spatiale
[Termes IGN] densité de population
[Termes IGN] emprise au sol
[Termes IGN] indicateur démographique
[Termes IGN] ville
[Termes IGN] zone urbaineRésumé : (Auteur) Cet article propose une approche, basée en grande partie sur la télédétection, dans un souci d'examiner les potentialités des images de satellite Alsat 2-A pour l'analyse urbaine. Les tissus urbains sont caractérisés par une complexité liée notamment à la forme, la typologie et la densité. En outre, la densité urbaine est déterminée souvent par les dimensions sociales, culturelles et historiques de chaque région laquelle la ville est localisée. Il est à signaler que la réalisation ou la révision des instruments d'aménagement et d'urbanisme s'appuierait sur les indicateurs de la densité urbaine (COS, CES) pour rendre la réalité à l'échelle des quartiers. Nous attachons à travers cette étude à calculer et déduire ces indicateurs par le biais des images satellitaires ALsat-2A tout en comptant sur une méthode originale et automatique sans faire le déplacement sur le terrain. Numéro de notice : A2018-562 Affiliation des auteurs : non IGN Thématique : IMAGERIE/URBANISME Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92153
in Bulletin des sciences géographiques > n° 31 (2017 - 2018) . - pp 46 - 53[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 253-2018011 RAB Revue Centre de documentation En réserve L003 Disponible Use of unsupervised classification for the determination of prevailing land use typology / Miha Konjar in Geodetski vestnik, vol 61 n° 4 (December 2017 - February 2018)PermalinkMapping fine-scale population distributions at the building level by integrating multisource geospatial big data / Yao Yao in International journal of geographical information science IJGIS, vol 31 n° 5-6 (May-June 2017)PermalinkImproving large area population mapping using geotweet densities / Nirav N. Patel in Transactions in GIS, vol 21 n° 2 (April 2017)PermalinkInferring spatial scale change in an isopleth map / J. Lin in Cartographic journal (the), Vol 54 n° 1 (February 2017)PermalinkDéveloppement d'un outil cartographique dasymétrique pour la modélisation de la répartition de densité de population / Safa Fennia (2017)PermalinkCharacterizing European urban settlements from population data : a cartographic approach / David Serano Giné in Cartography and Geographic Information Science, vol 43 n° 5 (November 2016)PermalinkSpace-time multiple regression model for grid-based population estimation in urban areas / Ko Ko Lwin in International journal of geographical information science IJGIS, vol 30 n° 7- 8 (July - August 2016)PermalinkElaboration d’un zonage de tissus urbains : introduire de la structure dans un référentiel carroyé / Johanna Baro in Revue internationale de géomatique, vol 26 n° 1 (janvier - mars 2016)PermalinkLa ville à l’échelle de l’Europe : apports du couplage et de l’expertise de bases de données issues de l’imagerie satellitale / Anne Bretagnolle in Revue internationale de géomatique, vol 26 n° 1 (janvier - mars 2016)PermalinkUtilisation des technologies géospatiales pour l'évaluation des transformations spatiales dues aux pressions anthropiques dans le canton Afféma (Sud-est ivoirien) / Armand Kangah in Photo interprétation, European journal of applied remote sensing, vol 51 n° 3 (septembre 2015)Permalink