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Considering spatiotemporal processes in big data analysis: Insights from remote sensing of land cover and land use / Alexis Comber in Transactions in GIS, Vol 23 n° 5 (October 2019)  

Public [article]  inTransactions in GIS > Vol 23 n° 5 (October 2019) . - pp 879 - 891 Titre : Considering spatiotemporal processes in big data analysis: Insights from remote sensing of land cover and land use Type de document : Article/Communication Auteurs : Alexis Comber, Auteur ; Michael A. Wulder, Auteur Année de publication : 2019 Article en page(s) : pp 879 - 891 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] détection de changement [Termes IGN] données spatiotemporelles [Termes IGN] inventaire de la végétation [Termes IGN] métadonnées [Termes IGN] occupation du sol [Termes IGN] série temporelle [Termes IGN] télédétection [Termes IGN] utilisation du sol Résumé : (auteur) Data are increasingly spatio‐temporal—they are collected some‐where and at some‐time. The role of proximity in spatial process is well understood, but its value is much more uncertain for many temporal processes. Using the domain of land cover/land use (LCLU), this article asserts that analyses of big data should be grounded in understandings of underlying process. Processes exhibit behaviors over both space and time. Observations and measurements may or may not coincide with the process of interest. Identifying the presence or absence of a given process, for instance disentangling vegetation phenology from stress, requires data analysis to be informed by knowledge of the process characteristics and, critically, how these manifest themselves over the spatio‐temporal unit of analysis. Drawing from LCLU, we emphasize the need to identify process and consider process phase to quantify important signals associated with that process. The aim should be to link the seriality of the spatio‐temporal data to the phase of the process being considered. We elucidate on these points and opportunities for insights and leadership from the geographic community. Numéro de notice : A2019-549 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12559 Date de publication en ligne : 08/07/2019 En ligne : https://doi.org/10.1111/tgis.12559 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94199 [article]

Creating a conceptual framework to improve the re‐usability of open geographic data in cities / Fernando Benitez‐Paez in Transactions in GIS, vol 22 n° 3 (June 2018)  

Public [article]  inTransactions in GIS > vol 22 n° 3 (June 2018) . - pp 806 - 822 Titre : Creating a conceptual framework to improve the re‐usability of open geographic data in cities Type de document : Article/Communication Auteurs : Fernando Benitez‐Paez, Auteur ; Alexis Comber, Auteur ; Sergio Trilles, Auteur ; Joaquin Huerta, Auteur Année de publication : 2018 Article en page(s) : pp 806 - 822 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Infrastructure de données [Termes IGN] cadre conceptuel [Termes IGN] collectivité territoriale [Termes IGN] Colombie [Termes IGN] données localisées numériques [Termes IGN] données ouvertes [Termes IGN] Espagne [Termes IGN] indicateur [Termes IGN] réutilisation des données [Termes IGN] Valence (Espagne) Résumé : (Auteur) Open data has a profound effect on the working environment within which information is created and shared at all levels. At the local government level, open data initiatives have resulted in higher transparency in policy, a greater engagement between decision‐makers and citizens, and have changed the culture about how data analysis and evidence are used to support local governance. This article, based on data collected through an on‐line survey, participatory workshops with data user communities in four cities (in Colombia and Spain), and interviews with Valencia good‐government office, identifies four elements for a conceptual framework to improve the re‐usability of open geographic data in cities. The essential elements defined in this research are the definition of data user communities and their needs, the creation of the community of reuse, user‐focused metadata, and reuse‐focused legal terms. The definition of these indicators provides a framework for authorities to re‐shape their current open data strategy to include data user requirements. At the end of this article, a roadmap for future research and implementation is presented, considering some reflections on the conceptual framework. Numéro de notice : A2018-579 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Actes nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12449 Date de publication en ligne : 17/08/2018 En ligne : https://doi.org/10.1111/tgis.12449 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92326 [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]

Crowdsourcing, citizen science or volunteered geographic information? The current state of crowdsourced geographic information / Linda M. See in ISPRS International journal of geo-information, vol 5 n° 5 (May 2016)    

Public [article]  inISPRS International journal of geo-information > vol 5 n° 5 (May 2016) . - pp 1 - 23 Titre : Crowdsourcing, citizen science or volunteered geographic information? The current state of crowdsourced geographic information Type de document : Article/Communication Auteurs : Linda M. See, Auteur ; Peter Mooney, Auteur ; Giles M. Foody, Auteur ; Lucy Bastin, Auteur ; Alexis Comber, Auteur ; Jacinto Estima, Auteur ; Steffen Fritz, Auteur ; Norman Kerle, Auteur ; Bin Jiang, Auteur ; Mari Laakso, Auteur ; Hai-Ying Liu, Auteur ; Grega Milčinski, Auteur ; Matej Nikšič, Auteur ; Marco Painho, Auteur ; Andrea Pődör, Auteur ; Ana-Maria Olteanu-Raimond , Auteur ; Martin Rutzinger, Auteur Année de publication : 2016 Article en page(s) : pp 1 - 23 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes IGN] analyse du discours [Termes IGN] cartographie collaborative [Termes IGN] citoyen [Termes IGN] données localisées des bénévoles [Termes IGN] état de l'art [Termes IGN] participation du public [Termes IGN] production participative [Termes IGN] science citoyenne [Termes IGN] terminologie Résumé : (Auteur) Citizens are increasingly becoming an important source of geographic information, sometimes entering domains that had until recently been the exclusive realm of authoritative agencies. This activity has a very diverse character as it can, amongst other things, be active or passive, involve spatial or aspatial data and the data provided can be variable in terms of key attributes such as format, description and quality. Unsurprisingly, therefore, there are a variety of terms used to describe data arising from citizens. In this article, the expressions used to describe citizen sensing of geographic information are reviewed and their use over time explored, prior to categorizing them and highlighting key issues in the current state of the subject. The latter involved a review of ~100 Internet sites with particular focus on their thematic topic, the nature of the data and issues such as incentives for contributors. This review suggests that most sites involve active rather than passive contribution, with citizens typically motivated by the desire to aid a worthy cause, often receiving little training. As such, this article provides a snapshot of the role of citizens in crowdsourcing geographic information and a guide to the current status of this rapidly emerging and evolving subject. Numéro de notice : A2016--119 Affiliation des auteurs : LASTIG COGIT+Ext (2012-2019) Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/ijgi5050055 En ligne : http://dx.doi.org/10.3390/ijgi5050055 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84782 [article]

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