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The use of geometric indicators to estimate the quantitative completeness of street blocks in OpenStreetMap / Qi Zhou in Transactions in GIS, vol 22 n° 6 (December 2018)  

Public [article]  inTransactions in GIS > vol 22 n° 6 (December 2018) . - pp 1550 - 1572 Titre : The use of geometric indicators to estimate the quantitative completeness of street blocks in OpenStreetMap Type de document : Article/Communication Auteurs : Qi Zhou, Auteur ; YuanJian Tian, Auteur Année de publication : 2018 Article en page(s) : pp 1550 - 1572 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes descripteurs IGN] données localisées des bénévoles [Termes descripteurs IGN] exhaustivité des données [Termes descripteurs IGN] îlot urbain [Termes descripteurs IGN] indicateur spatial [Termes descripteurs IGN] OpenStreetMap [Termes descripteurs IGN] qualité des données Résumé : (Auteur) OpenStreetMap (OSM) is a free global map dataset that was created by volunteers around the world. This inevitably means that there are a number of quality issues with the final OSM product, however. Extensive research has therefore been carried out to assess the quality of this product by applying a range of measures versus reference datasets, but little effort to date has been focused on quantitative quality estimation without reference datasets. The aim of this study is therefore to quantitatively estimate the completeness of street blocks in an OSM dataset. This was accomplished by initially exploring the relationship between geometric indicators (i.e., area, perimeter, and density) and street block completeness in an OSM road dataset, before these relationships were applied to quantitatively estimate completeness in other datasets. The results of this study show that: (1) street block completeness is positively correlated with density and negatively correlated with area and perimeter; and (2) in most cases, estimated completeness values for all street blocks within an OSM road dataset do not differ by more than 10% in absolute terms from actual completeness values. These results indicate that geometric indicators can be used as proxies to quantitatively estimate road completeness in OSM datasets. Numéro de notice : A2018-568 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12486 date de publication en ligne : 10/12/2018 En ligne : https://doi.org/10.1111/tgis.12486 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92287 [article]

Exploring the relationship between density and completeness of urban building data in OpenStreetMap for quality estimation / Qi Zhou in International journal of geographical information science IJGIS, vol 32 n° 1-2 (January - February 2018)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 32 n° 1-2 (January - February 2018) . - pp 257 - 281 Titre : Exploring the relationship between density and completeness of urban building data in OpenStreetMap for quality estimation Type de document : Article/Communication Auteurs : Qi Zhou, Auteur Année de publication : 2018 Article en page(s) : pp 257 - 281 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes descripteurs IGN] densité du bâti [Termes descripteurs IGN] exhaustivité des données [Termes descripteurs IGN] OpenStreetMap [Termes descripteurs IGN] qualité des données [Termes descripteurs IGN] résidu [Termes descripteurs IGN] zone urbaine Résumé : (Auteur) OpenStreetMap (OSM) is a free spatial data source based on crowd sourced data. Although the OSM data have a range of applications, such as generating 3D models, and routing and navigation, quality issues are still significant concerns when using the data. Several studies have undertaken quality assessments by comparing OSM data with reference data. However, reference data are not always available due to high costs or licensing restrictions, and very few studies have quantitatively estimated the quality of OSM data under conditions where the corresponding reference data are not available. This study proposed the use of a building density (or building coverage ratio) indicator as a proxy, and designed a series of experiments involving different study areas to quantitatively explore the relationship between building density and building completeness for OSM data in urban areas. The residuals (estimated building completeness and reference building completeness) were also analyzed. Two main results were found from the experiments. (1) There was an approximate linear relationship between building density and building completeness in the OSM data. More precisely, the building completeness of OSM data was approximately 3.4–4 times the building density of OSM data. (2) Approximately 70–80% of the absolute residuals were smaller than 10%, and 80–90% of them were smaller than 20%. This shows that, in most cases, estimated building completeness was close to the corresponding reference building completeness. Therefore, we concluded that the building density indicator is a potential proxy for the quantitative completeness estimation of OSM building data in urban areas. The limitations of using this indicator were also addressed. Numéro de notice : A2018-026 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2017.1395883 En ligne : https://doi.org/10.1080/13658816.2017.1395883 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89178 [article]

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How many samples are needed? An investigation of binary logistic regression for selective omission in a road network / Qi Zhou in Cartography and Geographic Information Science, vol 43 n° 5 (November 2016)  

Public [article]  inCartography and Geographic Information Science > vol 43 n° 5 (November 2016) . - pp 405 - 416 Titre : How many samples are needed? An investigation of binary logistic regression for selective omission in a road network Type de document : Article/Communication Auteurs : Qi Zhou, Auteur ; Zhilin Li, Auteur Année de publication : 2016 Article en page(s) : pp 405 - 416 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] apprentissage dirigé [Termes descripteurs IGN] échantillonnage [Termes descripteurs IGN] généralisation cartographique automatisée [Termes descripteurs IGN] régression logistique [Termes descripteurs IGN] réseau routier [Vedettes matières IGN] Généralisation Résumé : (Auteur) Selective omission in a road network (or road selection) means to retain more important roads, and it is a necessary operator to transform a road network at a large scale to that at a smaller scale. This study discusses the use of the supervised learning approach to road selection, and investigates how many samples are needed for a good performance of road selection. More precisely, the binary logistic regression is employed and three road network data with different sizes and different target scales are involved for testing. The different percentages and numbers of strokes are randomly chosen for training a logistic regression model, which is further applied into the untrained strokes for validation. The performances of using the different sample sizes are mainly evaluated by an error rate estimate. Significance tests are also employed to investigate whether the use of different sample sizes shows statistically significant differences. The experimental results show that in most cases, the error rate estimate is around 0.1–0.2; more importantly, only a small number (e.g., 50–100) of training samples is needed, which indicates the usability of binary logistic regression for road selection. Numéro de notice : A2016-691 Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/15230406.2015.1104265 En ligne : https://doi.org/10.1080/15230406.2015.1104265 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82019 [article]

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Empirical determination of geometric parameters for selective omission in a road network / Qi Zhou in International journal of geographical information science IJGIS, vol 30 n° 1-2 (January - February 2016)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 30 n° 1-2 (January - February 2016) . - pp 263 - 299 Titre : Empirical determination of geometric parameters for selective omission in a road network Type de document : Article/Communication Auteurs : Qi Zhou, Auteur ; Zhilin Li, Auteur Année de publication : 2016 Article en page(s) : pp 263 - 299 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] généralisation cartographique automatisée [Termes descripteurs IGN] généralisation géométrique (de visualisation) [Termes descripteurs IGN] Hong-Kong [Termes descripteurs IGN] modèle empirique [Termes descripteurs IGN] Nouvelle-Zélande [Termes descripteurs IGN] réseau routier [Termes descripteurs IGN] visualisation cartographique [Vedettes matières IGN] Généralisation Résumé : (auteur) Selective omission in a road network is a necessary operation for road network generalization. Most existing selective omission approaches involve one or two geometric parameters at a specific scale to determine which roads should be retained or eliminated. This study proposes an approach for determining the empirical threshold for such a parameter. The idea of the proposed approach is to first subdivide a large road network, and then to use appropriate threshold(s) obtained from one or several subdivisions to infer an appropriate threshold for the large one. A series of experiments was carried out to validate the proposed approach. Specifically, the road network data for New Zealand and Hong Kong at different scales (ranging from 1:50,000 to 1:250,000) were used as the experimental data, and subdivided according to different modes (i.e. administrative boundary data, a regular grid of different sizes, different update years, and different road network patterns). Not only geometric parameters, but also structural and hybrid parameters of existing selective omission approaches were involved in the testing. The experimental results show that although the most appropriate thresholds obtained from different subdivisions are not always the same, in most cases, the appropriate threshold ranges often overlap, especially for geometric parameters, and they also overlap with those obtained from the large road network data. This finding is consistent with the use of different subdivision modes, which verifies the effectiveness of the proposed approach. Several issues involving the use of the proposed approach are also addressed. Numéro de notice : A2016-088 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2015.1085538 En ligne : https://doi.org/10.1080/13658816.2015.1085538 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79873 [article]

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A vector field model to handle the displacement of multiple conflicts in building generalization / Tinghua Ai in International journal of geographical information science IJGIS, vol 29 n° 8 (August 2015)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 29 n° 8 (August 2015) . - pp 1310 - 1331 Titre : A vector field model to handle the displacement of multiple conflicts in building generalization Type de document : Article/Communication Auteurs : Tinghua Ai, Auteur ; Xiang Zhang, Auteur ; Qi Zhou, Auteur ; Min Yang, Auteur Année de publication : 2015 Article en page(s) : pp 1310 - 1331 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] conflit d'espace [Termes descripteurs IGN] détection de conflit [Termes descripteurs IGN] généralisation cartographique automatisée [Termes descripteurs IGN] généralisation du bâti [Termes descripteurs IGN] partition des données [Termes descripteurs IGN] relation spatiale [Termes descripteurs IGN] triangulation de Delaunay [Vedettes matières IGN] Généralisation Résumé : (Auteur) In map generalization, the displacement operation attempts to resolve proximity conflicts to guarantee map legibility. Owing to the limited representation space, conflicts may occur between both the same and different features under different contexts. A successful displacement should settle multiple conflicts, suppress the generation of secondary conflicts after moving some objects, and preserve the distribution patterns. The effect of displacement can be understood as a force that pushes related objects away with properties of propagation and distance decay. This study borrows the idea of vector fields from physics discipline and establishes a vector field model to handle the displacement of multiple conflicts in building generalization. A scalar field is first constructed based on a Delaunay triangulation skeleton to partition the buildings being examined (e.g., a street block). Then, we build a vector field to conduct displacement measurements through the detection of conflicts from multiple sources. The direction and magnitude of the displacement force are computed based on an iso-line model of vector field. The experiment shows that this global method can settle multiple conflicts and preserve the spatial relations and important building patterns. Numéro de notice : A2015-604 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2015.1019886 En ligne : https://doi.org/10.1080/13658816.2015.1019886 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78025 [article]

Use of artificial neural networks for selective omission in updating road networks / Qi Zhou in Cartographic journal (the), vol 51 n° 1 (February 2014)

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