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Recognizing text in raster maps / Yao-Yi Chiang in Geoinformatica, vol 19 n° 1 (January - March 2015)  

Public [article]  inGeoinformatica > vol 19 n° 1 (January - March 2015) . - pp 1 - 27 Titre : Recognizing text in raster maps Type de document : Article/Communication Auteurs : Yao-Yi Chiang, Auteur ; Craig A. Knoblock, Auteur Année de publication : 2015 Article en page(s) : pp 1 - 27 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] carte ancienne [Termes IGN] données maillées [Termes IGN] information géographique [Termes IGN] placement des écritures [Termes IGN] reconnaissance de caractères [Termes IGN] système d'information cartographique [Termes IGN] toponyme Résumé : (auteur) Text labels in maps provide valuable geographic information by associating place names with locations. This information from historical maps is especially important since historical maps are very often the only source of past information about the earth. Recognizing the text labels is challenging because heterogeneous raster maps have varying image quality and complex map contents. In addition, the labels within a map do not follow a fixed orientation and can have various font types and sizes. Previous approaches typically handle a specific type of map or require intensive manual work. This paper presents a general approach that requires a small amount of user effort to semi-automatically recognize text labels in heterogeneous raster maps. Our approach exploits a few examples of text areas to extract text pixels and employs cartographic labeling principles to locate individual text labels. Each text label is then rotated automatically to horizontal and processed by conventional OCR software for character recognition. We compared our approach to a state-of-art commercial OCR product using 15 raster maps from 10 sources. Our evaluation shows that our approach enabled the commercial OCR product to handle raster maps and together produced significant higher text recognition accuracy than using the commercial OCR alone. Numéro de notice : A2015-484 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-014-0203-9 Date de publication en ligne : 21/02/2014 En ligne : https://doi.org/10.1007/s10707-014-0203-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77246 [article]

Efficient continuous top-k spatial keyword queries on road networks / Long Guo in Geoinformatica, vol 19 n° 1 (January - March 2015)  

Public [article]  inGeoinformatica > vol 19 n° 1 (January - March 2015) . - pp 29 - 60 Titre : Efficient continuous top-k spatial keyword queries on road networks Type de document : Article/Communication Auteurs : Long Guo, Auteur ; Jie Shao, Auteur ; Htoo Htet Aung, Auteur ; Kian-Lee Tan, Auteur Année de publication : 2015 Article en page(s) : pp 29 - 60 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] espace euclidien [Termes IGN] extraction de données [Termes IGN] géobalise [Termes IGN] géopositionnement [Termes IGN] requête spatiale [Termes IGN] réseau routier [Termes IGN] système d'information géographique [Termes IGN] traitement de données localisées Résumé : (auteur) With the development of GPS-enabled mobile devices, more and more pieces of information on the web are geotagged. Spatial keyword queries, which consider both spatial locations and textual descriptions to find objects of interest, adapt well to this trend. Therefore, a considerable number of studies have focused on the interesting problem of efficiently processing spatial keyword queries. However, most of them assume Euclidean space or examine a single snapshot query only. This paper investigates a novel problem, namely, continuous top-k spatial keyword queries on road networks, for the first time. We propose two methods that can monitor such moving queries in an incremental manner and reduce repetitive traversing of network edges for better performance. Experimental evaluation using large real datasets demonstrates that the proposed methods both outperform baseline methods significantly. Discussion about the parameters affecting the efficiency of the two methods is also presented to reveal their relative advantages. Numéro de notice : A2015-485 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-014-0204-8 En ligne : https://doi.org/10.1007/s10707-014-0204-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77248 [article]

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)  

Public [article]  inGeoinformatica > vol 19 n° 1 (January - March 2015) . - pp 85 - 115 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] Géovisualisation Résumé : (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 [article]

Domain-driven co-location mining / Frédéric Flouvat in Geoinformatica, vol 19 n° 1 (January - March 2015)  

Public [article]  inGeoinformatica > vol 19 n° 1 (January - March 2015) . - pp 147 - 183 Titre : Domain-driven co-location mining Type de document : Article/Communication Auteurs : Frédéric Flouvat, Auteur ; Jean-François N’guyen Van Soc, Auteur ; Elise Desmier, Auteur ; Nazha Selmaoui-Folcher, Auteur Année de publication : 2015 Article en page(s) : pp 147 - 183 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes d'information géographique [Termes IGN] co-positionnement [Termes IGN] érosion [Termes IGN] exploration de données géographiques [Termes IGN] géologie [Termes IGN] PostGIS [Termes IGN] sol [Termes IGN] système expert [Termes IGN] visualisation cartographique Résumé : (auteur) Co-location mining is a classical problem in spatial pattern mining. Considering a set of boolean spatial features, the goal is to find subsets of features frequently located together. It has wide applications in environmental management, public safety, transportation or tourism. These last years, many algorithms have been proposed to extract frequent co-locations. However, most solutions do a “data-centered knowledge discovery” instead of a “expert-centered knowledge discovery”. Successfully providing useful and interpretable patterns to experts is still an open problem. In this setting, we propose a domain-driven co-location mining approach that combines constraint-based mining and cartographic visualization. Experts can push new domain constraints into the mining algorithm, resulting in more relevant patterns and more efficient extraction. Then, they can visualize solutions using a new concise and intuitive cartographic visualization of co-locations. Using this original visualization approach, they identify new interesting patterns, and use uninteresting ones to define new constraints and refine their analysis. These proposals have been integrated into a prototype based on PostGIS geographic information system. Experiments have been done using a real geological datasets studying soil erosion, and results have been validated by a domain expert. Numéro de notice : A2015-487 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-014-0209-3 En ligne : https://doi.org/10.1007/s10707-014-0209-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77250 [article]