Descripteur
Documents disponibles dans cette catégorie (9)
Ajouter le résultat dans votre panier Affiner la recherche Interroger des sources externesEtendre la recherche sur niveau(x) vers le bas
On determining orthometric heights from a corrector surface model based on leveling observations, GNSS, and a geoid model / Su-Kyung Kim in Journal of applied geodesy, vol 12 n° 4 (October 2018)
Titre : On determining orthometric heights from a corrector surface model based on leveling observations, GNSS, and a geoid model Type de document : Article/Communication Auteurs : Su-Kyung Kim, Auteur ; Jihye Park, Auteur ; Daniel T. Gillins, Auteur ; Michael Dennis, Auteur Année de publication : 2018 Article en page(s) : pp 323 - 333 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] altitude orthométrique
[Termes IGN] coefficient de corrélation
[Termes IGN] compensation de coordonnées
[Termes IGN] erreur en position
[Termes IGN] géoïde gravimétrique
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] North American Vertical Datum 1988
[Termes IGN] Oregon (Etats-Unis)
[Termes IGN] système de référence altimétrique
[Vedettes matières IGN] AltimétrieRésumé : (auteur) Leveling is a traditional geodetic surveying technique that has been used to realize a vertical datum. However, this technique is time consuming and prone to accumulate errors, where it relies on starting from one station with a known orthometric height. Establishing orthometric heights using Global Navigation Satellite Systems (GNSS) and a geoid model has been suggested [14], but this approach may involve less precisions than the direct measurements from leveling. In this study, an experimental study is presented to adjust the highly accurate leveling observations along with orthometric heights derived from GNSS observations and a geoid model. For the geoid model, the National Geodetic Survey’s gravimetric geoid model (TxGEOID16B) and hybrid geoid model (GEOID12B) were applied. Uncertainties in the leveled height differences, GNSS derived heights, and the geoid models were modeled, and a combined adjustment was implemented to construct the optimal combination of orthometric, ellipsoidal, and geoid height at each mark. As a result, the discrepancy from the published orthometric heights and the CSM (Corrector Surface Model) based adjusted orthometric heights with GEOID12B showed a mean and RMS of -8.5 mm and 16.6 mm, respectively, while TxGEOID16B had a mean and RMS of 28.9 mm and 34.6 mm, respectively. It should be emphasized that this approach was not influenced by the geodetic distribution of the stations where the correlation coefficients between the distance from the center of the surveying network and the discrepancy from the published heights using TxGEOID16B and GEOID12B are 0.03 and 0.36, respectively. Numéro de notice : A2018-672 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2018-0014 Date de publication en ligne : 29/08/2018 En ligne : https://doi.org/10.1515/jag-2018-0014 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91004
in Journal of applied geodesy > vol 12 n° 4 (October 2018) . - pp 323 - 333[article]
Titre : PPPH : a MATLAB-based software for multi-GNSS precise point positioning analysis Type de document : Article/Communication Auteurs : Berkay Bahadur, Auteur ; Metin Nohutcu, Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] affaiblissement géométrique de la précision
[Termes IGN] données GNSS
[Termes IGN] erreur en position
[Termes IGN] horloge du récepteur
[Termes IGN] Matlab
[Termes IGN] positionnement ponctuel précis
[Termes IGN] retard troposphérique zénithal
[Vedettes matières IGN] Traitement de données GNSSRésumé : (Auteur) The integration of different GNSS constellations offers considerable opportunities to improve Precise Point Positioning (PPP) performance. Being aware of the limited number of the alternatives that utilize the potential advantages of the multi-constellation and multi-frequency GNSS, we developed a MATLAB-based GNSS analysis software, named PPPH. PPPH is capable of processing GPS, GLONASS, Galileo and BeiDou data, and forming their different combinations depending on user’s preference. Thanks to its user-friendly graphical interface, PPPH allows users to determine a variety of processing options and parameters. In addition to an output file including the estimated parameters for every single epoch, PPPH also presents several analyzing and plotting tools for evaluating the results, such as positioning error, tropospheric zenith total delay, receiver clock estimation, satellite number, dilution of precisions. On the other hand, we conducted experimental tests to both validate the performance of PPPH and assess the potential benefits of multi-GNSS on PPP. The results indicate that PPPH provides comparable PPP solution with the general standards and also contributes to the improvement of PPP performance with the integration of multi-GNSS. Consequently, we introduce a GNSS analysis software that is easy to use, has a robust performance and is open to progress with its modular structure. Numéro de notice : A2018-377 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-018-0777-z Date de publication en ligne : 18/08/2018 En ligne : https://doi.org/10.1007/s10291-018-0777-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90781
in GPS solutions > vol 22 n° 4 (October 2018)[article]
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 IGN] analyse de sensibilité
[Termes IGN] bâtiment
[Termes IGN] CityGML
[Termes IGN] erreur en position
[Termes IGN] modèle 3D de l'espace urbain
[Termes IGN] niveau de détail
[Termes IGN] propagation d'erreur
[Termes IGN] SIG 3D
[Termes 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 Affiliation des auteurs : non IGN 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 : Error analysis of satellite attitude determination using a vision-based approach Type de document : Article/Communication Auteurs : Ludovico Carozza, Auteur ; Alessandro Bevilacqua, Auteur Année de publication : 2013 Article en page(s) : pp 19 - 29 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] acquisition d'images
[Termes IGN] angle de visée
[Termes IGN] erreur en position
[Termes IGN] orientation du capteur
[Termes IGN] réalité de terrain
[Termes IGN] satellite agile
[Termes IGN] simulationRésumé : (Auteur) Improvements in communication and processing technologies have opened the doors to exploit on-board cameras to compute objects’ spatial attitude using only the visual information from sequences of remote sensed images. The strategies and the algorithmic approach used to extract such information affect the estimation accuracy of the three-axis orientation of the object. This work presents a method for analyzing the most relevant error sources, including numerical ones, possible drift effects and their influence on the overall accuracy, referring to vision-based approaches. The method in particular focuses on the analysis of the image registration algorithm, carried out through on-purpose simulations. The overall accuracy has been assessed on a challenging case study, for which accuracy represents the fundamental requirement. In particular, attitude determination has been analyzed for small satellites, by comparing theoretical findings to metric results from simulations on realistic ground-truth data. Significant laboratory experiments, using a numerical control unit, have further confirmed the outcome. We believe that our analysis approach, as well as our findings in terms of error characterization, can be useful at proof-of-concept design and planning levels, since they emphasize the main sources of error for visual based approaches employed for satellite attitude estimation. Nevertheless, the approach we present is also of general interest for all the affine applicative domains which require an accurate estimation of three-dimensional orientation parameters (i.e., robotics, airborne stabilization). Numéro de notice : A2013-487 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.05.007 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.05.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32625
in ISPRS Journal of photogrammetry and remote sensing > vol 83 (September 2013) . - pp 19 - 29[article]Réservation
Réserver ce documentExemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 081-2013091 RAB Revue Centre de documentation En réserve 3L Disponible
Titre : The Forward Propagation of Integrated System Component Errors within Airborne Lidar Data Type de document : Article/Communication Auteurs : T. Goulden, Auteur ; Christopher Hopkinson, Auteur Année de publication : 2010 Article en page(s) : pp 589 - 601 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] données lidar
[Termes IGN] erreur en position
[Termes IGN] géoréférencement direct
[Termes IGN] GPS-INS
[Termes IGN] propagation d'erreur
[Termes IGN] varianceRésumé : (Auteur) Error estimates of lidar observations are obtained by applying the General Law of Propagation of Variances (GLOPOV) to the direct georeferencing equation. Within the formulation of variance propagation, the most important consideration is the values used to describe the error of the hardware component observations including the global positioning system, inertial measurement unit, laser ranger, and laser scanner (angular encoder noise and beam divergence). Data tested yielded in general, pessimistic predictions as 85 percent of residuals were within the predicted error level. Simulated errors for varying scan angles and altitudes produced horizontal errors largely influenced by IMU subsystem error as well as angular encoder noise and beam divergence. GPS subsystem errors contribute the largest proportion of vertical error only at shallow scan angles and low altitudes. The transformation of the domination of GPS related error sources to total vertical error occurs at scan angles of 23°, 13°, and 8° at flying heights of 1,200 m, 2,000 m, and 3,000 m AGL, respectively. Copyright ASPRS Numéro de notice : A2010-162 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.76.5.589 En ligne : https://doi.org/10.14358/PERS.76.5.589 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30357
in Photogrammetric Engineering & Remote Sensing, PERS > vol 76 n° 5 (May 2010) . - pp 589 - 601[article]Réservation
Réserver ce documentExemplaires (2)
Code-barres Cote Support Localisation Section Disponibilité 105-2010051 RAB Revue Centre de documentation En réserve 3L Disponible 105-2010052 RAB Revue Centre de documentation En réserve 3L Disponible PermalinkPermalinkPermalinkTheoretische und praktische Untersuchungen zur Genauigkeit der Photogrammetrie bei Erdmassenermittlung im Strassenbau / W. Brindopke (1960)
Permalink
