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Titre : Geospatial data on the web Type de document : Thèse/HDR Auteurs : Linda Van Den Brink, Auteur ; Jantien E. Stoter, Directeur de thèse Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2018 Autre Editeur : Delft [Pays-Bas] : Delft University of Technology Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 Importance : 232 p. Format : 21 x 30 cm Note générale : bibliographie
Dissertation for the purpose of obtaining the degree of doctor at Delft University of TechnologyLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web
[Termes descripteurs IGN] accès aux données localisées
[Termes descripteurs IGN] acquisition de données
[Termes descripteurs IGN] assimilation des données
[Termes descripteurs IGN] CityGML
[Termes descripteurs IGN] données hétérogènes
[Termes descripteurs IGN] données localisées
[Termes descripteurs IGN] données multisources
[Termes descripteurs IGN] données topographiques
[Termes descripteurs IGN] harmonisation des données
[Termes descripteurs IGN] outil d'aide à la décision
[Termes descripteurs IGN] RDF
[Termes descripteurs IGN] recherche d'information géographique
[Termes descripteurs IGN] réutilisation des données
[Termes descripteurs IGN] similitude sémantique
[Termes descripteurs IGN] Web des donnéesRésumé : (auteur) Geospatial data is an increasingly important information asset for decisionmaking, from simple every day decisions like where to park your car, to national and international policy on topics like infrastructure and environment.Because of the location aspect, geospatial data is often the linking pin between different datasets and therefore important for data integration. A lot of geospatial data is created, for example, as part of governmental processes and nowadays, also disseminated as open data, traditionally through "Spatial data infrastructures" (SDIs).There is a lot of potential for reusing this data in other domains than the domain and use case for which it was originally created. My main research question was: "How to reuse geospatial data, from different, heterogeneous sources, via the web across communities?" Several aspects of data disseminationmust be addressed before open data is actually in a good position for getting reused. These aspects have been coined the "FAIR principles": findability, accessibility, interoperability, and reusability. Note de contenu : 1- Introduction, research questions and methodology
2- Definition and establishment of a national 3D standard
3- Semantic Harmonisation
4- Geospatial Linked Data
5- Web of Data
6- Discussion, Conclusion and Future workNuméro de notice : 21836 Thématique : GEOMATIQUE/SOCIETE NUMERIQUE Nature : Thèse étrangère Note de thèse : PhD thesis : 3D Geo-Information : TU Delft : 2018 DOI : 10.4233/uuid:a0bd364d-f101-4337-91c5-92038b2a6d56 En ligne : https://www.ncgeo.nl/index.php/en/publicatiesgb/publications-on-geodesy/item/278 [...] Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91364 Documents numériques
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Geospatial data on the web... - pdf auteurAdobe Acrobat PDF
Titre : Level of detail in 3D city models Type de document : Thèse/HDR Auteurs : Filip Biljecki, Auteur ; Jantien E. Stoter, Auteur ; Hugo Ledoux, Auteur Editeur : Delft [Pays-Bas] : Delft University of Technology Année de publication : 2017 Note générale : bibliographie
Doctoral dissertation, Delft university of technologyLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées
[Termes descripteurs IGN] analyse de sensibilité
[Termes descripteurs IGN] bâtiment
[Termes descripteurs IGN] CityGML
[Termes descripteurs IGN] erreur en position
[Termes descripteurs IGN] modèle 3D de l'espace urbain
[Termes descripteurs IGN] niveau de détail
[Termes descripteurs IGN] propagation d'erreur
[Termes descripteurs IGN] SIG 3D
[Termes descripteurs IGN] spécificationRésumé : (auteur) The concept of level of detail (LOD) describes the content of 3D city models and it plays an essential role during their life cycle. On one hand it comes akin to the concepts of scale in cartography and LOD in computer graphics, on the other hand it is a standalone concept that requires attention. LOD has an influence on tendering and acquisition, and it has a hand in storage, maintenance, and application aspects. However, it has not been significantly researched, and this PhD thesis fills this void. This thesis reviews dozens of current LOD standards, revealing that most practitioners consider the LOD to be comprised solely of the geometric detail of data and there are disparate views on the concept as a whole. However, the research suggests that the LOD encompasses additional metrics, such as semantics and texture. The thesis formalises the concept, enabling integration and comparison of current LOD standards. The established framework may be applied to cartography and to different forms of 3D geoinformation such as point clouds. Following the formalised concept, a new LOD specification is presented improving the LOD concept in the current OGC CityGML 2.0 standard, a prominent norm in the 3D GIS industry. The specification introduces 16 LODs for buildings that are shaped after analysing the capabilities of acquisition techniques and a large number of real-world datasets. The improved LOD specification may be integrated in product portfolios and tenders, preventing misunderstandings between stakeholders, and as a better language for communicating the specifics of a dataset to be acquired. The specification also considers different approaches to realise the data. Such geometric references result in dozens of different variants of the same LOD.3D data according to the LOD specification was generated using a procedural modelling engine that was developed over the course of the research. The engine is capable of producing 3D city models in a large number of different variants and according to the CityGML standard. The thesis also catalogues the many different ways to create 3D city models. A prominent technique for producing data in a different LOD is generalisation, i.e. simplifying a 3D city model. The inverse---augmenting the LOD of a dataset---has not been researched to a great extent, and this thesis gives an overview of the topic. This research demonstrates that it is possible to generate 3D city models without elevation measurements, inherently augmenting the LOD of coarser data (2D footprints). The method relies on machine learning: several attributes found in 2D datasets may hint at the height of a building, thus enabling extrusion and creating 3D city models suited for several applications.Some acquisition techniques may result in multi-LOD datasets, and nowadays there are some regions represented in different, independent datasets. However, it was found that possibilities to link such data are deficient. The lack of linking mechanisms inhibits acquisition, storage, and maintenance of multi-LOD data. Two methods for linking features across two or more LODs have been developed resulting in an increased consistency of multi-LOD datasets. The first method links matching geometries across multiple LODs, while the second method establishes a 4D data structure in which the LOD is modelled as the fourth (spatial) dimension.It is often believed that the more detailed 3D data the better. However, similarly as in computer graphics, dealing with data at fine LODs comes at a cost: such datasets are harder to obtain, their storage footprint is large, and their usage within a spatial analysis may be slow. Scarce research has been dedicated to investigating whether an increase in the LOD of the data brings a comparably significant increase in benefits when the data is used in a spatial analysis.First, an analysis using real-world multi-LOD data was carried out. Different LODs of spatial data covering the Netherlands was used in a spatial analysis to refine population maps, obtaining different results for each LOD. However, several problems are exposed, revealing that using real data for such investigations is not optimal.The remainder of the research focuses on using procedurally generated data for such experiments. Synthetic data in several different LODs has been generated and employed for four spatial analyses (estimation of the building shadow, envelope area, volume, and solar irradiation). The experiments result in different conclusions. Finer LODs usually bring some improvement to the quality of the spatial analysis, but not always and such may be negligible. The results of the experiments ultimately depend on the spatial analysis that is considered. The varying results between different spatial analyses make each of them unique. Furthermore, the benefit a finer LOD brings to a spatial analysis is not always clear and easily measurable. In short, striving to produce data at finer LODs may please the eye, but this is not always counter-balanced in the benefit it brings to a spatial analysis.A further addition to the equation above is that when realised, 3D city models are unavoidably burdened with acquisition errors. An error propagation analysis was performed by disturbing the procedurally generated datasets with a range of simulated positional errors. Comparisons have been made between the intentionally degraded datasets and their error-free counterparts, thus obtaining the magnitude of uncertainty the positional errors cause in a spatial analysis. Based on these experiments, several findings are discovered, most importantly:1. How the LODs are realised (which geometric references are used) has a larger influence than the LOD. A coarse LOD produced with a favourable geometric reference may yield better results than a finer LOD realised with an unfavourable reference.2. Positional errors considerably affect spatial analyses. The effect is comparable across similar LODs. Simpler LODs are sligthly less affected by positional errors, but they may contain a large systematic error.3. Errors induced in the acquisition process generally cancel out the improvement provided by finer LODs. The main conclusion is that in the considered spatial analyses the positional error has a significantly higher impact than the LOD. As a consequence, it is suggested that it is pointless to acquire geoinformation at a fine LOD if the acquisition method is not accurate, and instead it is advised to focus on the improvement of accuracy of the data. The thesis proposes additional research for future work. For example, since this research focuses specifically on 3D building models, it would be worth extending the research to other urban features such as roads and vegetation. Furthermore, quality control in 3D GIS does not encompass the evaluation of the LOD of data. Hence integration of the LOD in quality standards should be a priority for future work. Note de contenu : 1- Introduction
2- Background
3- Formalisation of LOD
4- Designing an LOD specification for buildings
5- Variants of LODs
6- Realisation of the specification
7- Generating 3D city models without elevation data
8- Managing multi-LOD data
9- Influence of LOD on spatial analyses (I)
10- Influence of LOD on spatial analyses (II)
11- Sensitivity of LOD to positional errors
12- Combining LOD and positional errors
13- Conclusions and future prospectsNuméro de notice : 17541 Thématique : GEOMATIQUE Nature : Thèse étrangère Note de thèse : Doctoral dissertation : : Delft university of technology : 2017 DOI : 10.4233/uuid:f12931b7-5113-47ef-bfd4-688aae3be248 En ligne : https://repository.tudelft.nl/islandora/object/uuid%3Af12931b7-5113-47ef-bfd4-68 [...] Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91250
Titre : Estimation of slack tide using GPS measurements on a buoy : A case study on buoy 18 in the Schelde Estuary Type de document : Mémoire Auteurs : M. Valk, Auteur Editeur : Delft [Pays-Bas] : Delft University of Technology Année de publication : 2011 Importance : 136 p. Format : 21 x 30 cm Note générale : bibliographie
Master of Science Thesis for obtaining the degree of Master of Science in Geomatics Engineering at Delft University of TechnologyLangues : Anglais (eng) Descripteur : [Termes descripteurs IGN] bouée
[Termes descripteurs IGN] données GPS
[Termes descripteurs IGN] Escaut (fleuve)
[Termes descripteurs IGN] estuaire
[Termes descripteurs IGN] étale
[Termes descripteurs IGN] marée océanique
[Termes descripteurs IGN] Pays-BasIndex. décimale : MX Mémoires divers Résumé : (auteur) In this thesis, a method is developed to estimate the moment of slack tide based on GPS measurements on a buoy. The moment of slack tide is the very moment the tidal current changes direction. The method is applied in the Schelde Estuary in the Netherlands. An estuary is the transition between two distinct water bodies: a river and a sea. Estuaries are very important as a transport link and a source of food. Interventions in the estuary bathymetry, like dredging, can have severe impact on the hydraulic behavior of the estuary. Knowledge of the physical phenomena that determine the tidal flow is important as they influence the environment of an estuary in many ways. One of the key parameters in tidal propagation is the phase lag, which is the difference in time between high or low water and the subsequent moment of slack. The main objective of this thesis is to estimate the moment of slack tide based on GPS measurements on a buoy ultimately with an accuracy in the order of 5-10 minutes. The buoy, which is used as an aid to navigation, is floating on the water and tied to the sea floor by a heavy anchor chain. In order to achieve this goal it is necessary to: investigate the performance of different GPS receivers in combination with different antennas and operating modes; analyze the motion of the buoy during several tidal cycles; develop a method to estimate the moment of slack tide based on GPS measurements on a buoy; and, investigate whether the results could be further improved by employing a Kalman filter that combines knowledge about the dynamics of the buoy and series of measurements over time as opposed to a single epoch slack tide estimation. […] Note de contenu : 1- Introduction
2- Background
3- Materials and methods
4- Results and discussion
5- Conclusions and RecommendationsNuméro de notice : 14867 Thématique : POSITIONNEMENT Nature : Mémoire masters divers Note de thèse : mémoire de master : Science in Geomatics Engineering : Delft University of Technology : 2011 En ligne : http://repository.tudelft.nl/view/ir/uuid%3A11a3bbc4-5013-4833-871d-1035fca04636 [...] Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75856 Documents numériques
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Titre : Variable-scale Geo-information Type de document : Thèse/HDR Auteurs : Martijn Meijers, Auteur Editeur : Delft [Pays-Bas] : Delft University of Technology Année de publication : 2011 Importance : 235 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-90-77029-28-2 Note générale : Bibliographie
PhD thesis Delft University of TechnologyLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées
[Termes descripteurs IGN] données localisées 2D
[Termes descripteurs IGN] données multiéchelles
[Termes descripteurs IGN] généralisation cartographique automatisée
[Termes descripteurs IGN] lissage de données
[Termes descripteurs IGN] modèle conceptuel de données localisées
[Termes descripteurs IGN] représentation multiple
[Termes descripteurs IGN] structure de données localisées
[Termes descripteurs IGN] variation d'échelleNote de contenu : 1 Setting the scene
1.1 Motivation for maps at variable scale
1.2 Objective and Research questions
1.3 Research scope
1.4 Methodology
1.5 Thesis outline
2 Research background
2.1 Modelling digital geographic space
2.2 From single-scale to multi-scale maps
2.3 Multi-scale hierarchies
2.4 Vario-scale structures
2.5 Progressive data transfer
2.6 Starting points for data at variable scale
3 Formalising valid vario-scale data
3.1 A preference for minimal redundancy
3.2 Formalisation of variable-scale partitions
3.3 Validation (and repair) of a 2d input partition
3.4 Closing remarks
4 Improving variable-scale data structures
4.1 Minimally redundant data storage
4.2 Simultaneous, topologically-safe line simplification
4.3 Collapsing areas: splitting over multiple neighbours
4.4 Closing remarks
5 Improving vario-scale data dissemination
5.1 Quantitative importance-setting approach
5.2 2d map for a thin client
5.3 Progressive data streaming
5.4 A cache-friendly and stateful solution
5.5 Closing remarks
6 A new era: smooth vario-scale data
6.1 Lessons learnt: a synthesis
6.2 Smooth data for the space-scale cube
6.3 Exploring possible drawbacks
6.4 Closing remarks
7 Conclusions and Future work
7.1 Conclusions
7.2 Recommendations for further researchNuméro de notice : 14464 Thématique : GEOMATIQUE/INFORMATIQUE Nature : Thèse étrangère Note de thèse : Thèse de doctorat : : Pays-Bas, Delft : 2011 En ligne : https://www.ncgeo.nl/index.php/en/publicatiesgb/publications-on-geodesy/item/257 [...] Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=45252 Documents numériques
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Variable-scale Geo-information - pdf éditeurAdobe Acrobat PDF
Titre : Integer GPS-ambiguity estimation without the receiver-satellite geometry Type de document : Monographie Auteurs : N.F. Jonkman, Auteur Editeur : Delft [Pays-Bas] : Delft University of Technology Année de publication : 1998 Collection : LGR-SERIES num. 18 Importance : 95 p. Format : 21 x 30 cm Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] ambiguïté entière
[Termes descripteurs IGN] compensation Lambda
[Termes descripteurs IGN] GPS en mode différentiel
[Termes descripteurs IGN] positionnement par GPS
[Termes descripteurs IGN] résolution d'ambiguïté
[Termes descripteurs IGN] satellite artificiel
[Termes descripteurs IGN] traitement de données GNSSRésumé : (Auteur) Integer ambiguity estimation is a prerequisite for fast and very precise relative positioning with the GPS. In this report we will study the usefulness of a particular approach consists of two steps : - adjusting GPS-observations for the unknown ambiguities according to the geometry-free observation model, and based on the resulting real valued ambiguity estimates and their precision description. - computing integer valued ambiguity estimates with the Lambda- or [l grec]-method. Numéro de notice : 67451 Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=61772 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 67451-01 30.61 Livre Centre de documentation Géodésie Disponible PermalinkPermalinkPermalinkA recursive procedure for computation and quality control of GPS differential corrections / X. Jin (1995)
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