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Inverse Probleme bei der Gravitationsfelsbestimmung mittels SST- und SGG-Satellitenmissionen Darstellungen / J. Kusche (2002)
Titre : Inverse Probleme bei der Gravitationsfelsbestimmung mittels SST- und SGG-Satellitenmissionen Darstellungen Titre original : [Problème inverse lors de la détermination du champ de gravitation au moyen des missions satellitaires SST et SGG] Type de document : Thèse/HDR Auteurs : J. Kusche, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2002 Collection : DGK - C Sous-collection : Dissertationen num. 548 Importance : 79 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-9585-4 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de gravitation
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] covariance
[Termes IGN] fonction spline
[Termes IGN] gradiométrie
[Termes IGN] itération
[Termes IGN] méthode des moindres carrés
[Termes IGN] mission spatiale
[Termes IGN] problème inverseIndex. décimale : 30.40 Géodésie physique Résumé : (Auteur) We investigate certain problems of downward continuation, which arise in the context of modern SST- and SGG-satellite missions designed for geopotential field recovery, in a generalized context. Fast solution techniques are presented and analyzed.
First the mathematical foundations of the treatment of inverse and ill-posed problems are reviewed. Then we begin with the definition of SST and SGG model problems, whose ill-posedness or, more precisely, ill-conditioning will be quantified using the spectrum of the normal equations. Different representations of the anomalous gravity field lead to different degrees of ill-conditioning. Our focus is oil representation techniques with space-localizing properties, rather than studying the familiar frequency-localizing spherical harmonics. Tykhonov-regularization as an essential tool for computing reasonable solutions in ill-posed problems is extensively studied within this thesis, including the implementation of a posteriori strategies for the determination of the regularization parameter.
After that we consider iterative methods for the solution of the regularized normal equations, which emerge from Galerkin discretizations. Two of the fastest techniques - conjugate gradients and multigrid iterations are presented first within an abstract setting, but in the sequel we give matrix algorithms for multigrid standalone iteration as well as multigrid preconditioning for CG. For the first time in this application, convergence properties are evaluated theoretically using the model problems. Finally, we consider the implementation of a posteriori parameter choice rules for Tykhonov-regularization in the framework of our iterative solvers.Numéro de notice : 13098 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54881 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13098-01 30.40 Livre Centre de documentation Géodésie Disponible 13098-02 30.40 Livre Centre de documentation Géodésie Disponible Mapping Dilution of Precision (MDOP) and map-matched GPS / Geoffrey Blewitt in International journal of geographical information science IJGIS, vol 16 n° 1 (january 2002)
[article]
Titre : Mapping Dilution of Precision (MDOP) and map-matched GPS Type de document : Article/Communication Auteurs : Geoffrey Blewitt, Auteur ; Georges E. Taylor, Auteur Année de publication : 2002 Article en page(s) : pp 55 - 67 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] affaiblissement géométrique de la précision
[Termes IGN] appariement de cartes
[Termes IGN] correction
[Termes IGN] erreur de positionnement
[Termes IGN] GPS assisté pour la navigation (technologies)
[Termes IGN] GPS en mode différentiel
[Termes IGN] méthode des moindres carrés
[Termes IGN] navigation automobile
[Termes IGN] positionnement différentiel
[Termes IGN] véhicule automobileRésumé : (Auteur) A novel method of map matching using the Global Positioning System (GPS) has been developed which uses digital mapping and height data to augment point position computation. This method reduces the error in position, which is a sum from several sources, including signal delay due to the ionosphere and atmosphere and until recently from 'selective availability' (S/A). S/A was imposed by the US military to degrade purposefully the accuracy of GPS, but was switched off on 2 May 2000, and is to be replaced with 'regional denial capabilities in lieu of global degradation' (Interagency GPS Executive Board, 2000). Taylor et al. (2001) describe the Road Reduction Filter (RRF) in detail. RRF is a method of detecting the correct road on which a vehicle is travelling. In the work described here, the position error vector is estimated in a formal least squares procedure, as the vehicle is moving. This estimate is a map-matched correction, that provides an autonomous alternative to DGPS for in-car navigation and fleet management. In this paper, a formula is derived for 'Mapped Dilution of Precision' (MDOP), defined as the theoretical ratio of position precision using map-matched corrections to that using perfect Differential GPS (DGPS) correction. This is shown to be purely a function of route geometry, and is computed for examples of basic road shapes. MDOP is favourable unless the route has less than a few degrees curvature for several kilometres. MDOP can thus provide an objective estimate of positioning precision to a vehicle driver. Precision estimates using MDOP are shown to agree well with 'true' positioning errors determined using high precision (cm) GPS carrier phase techniques. The exact location of a vehicle on a road is essential for accurate surveying applications. These include close range photogrammetry using digital video or still cameras and the verification of digital mapping by measured (GPS and other sensors) trajectories. Numéro de notice : A2002-004 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/13658810110075996 En ligne : https://doi.org/10.1080/13658810110075996 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21921
in International journal of geographical information science IJGIS > vol 16 n° 1 (january 2002) . - pp 55 - 67[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 079-02011 RAB Revue Centre de documentation En réserve L003 Disponible Improving area-based matching by using surface gradients in the pixel co-ordinate transformation / M. Mustaffar in ISPRS Journal of photogrammetry and remote sensing, vol 56 n° 1 (May - June 2001)
[article]
Titre : Improving area-based matching by using surface gradients in the pixel co-ordinate transformation Type de document : Article/Communication Auteurs : M. Mustaffar, Auteur ; H.L. Mitchell, Auteur Année de publication : 2001 Article en page(s) : pp 42 - 52 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] appariement de formes
[Termes IGN] géométrie affine
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle géométrique
[Termes IGN] photogrammétrie métrologiqueRésumé : (Auteur) Area-based least squares matching has existed since the 1980s, and its development may therefore be regarded by some photogrammetrists as complete. However, this is a relatively short time in a rapidly changing discipline, and the method does have scope for further refinement. This paper aims to enhance the fidelity of the fundamental mathematical model, which relates pixel positions in area-based matching. If successful, its benefit is seen to lie within close-range photogrammetry, in which object undulations, convergent camera directions and large image scales can introduce significant levels of perspective distortion. It is hypothesised that a model, which takes into account the surface shape within the match window, would provide a pixel position relationship which is applicable across larger windows than those which are applicable with the conventional matching model, based on an affine transformation. The use of larger windows for the image matching increases the redundancy. Revised co-ordinate transformations, based on mathematical surface models across the windows, are proposed in this paper. When tested on the measurement of real objects, even simple surface models are found to increase the complexity of the matching mathematics, but when compared with the traditional affine transformation solution using three test objects, precision improved noticeably. Generally, accuracy also improved, but the improvements were not as distinct as they were for precision. Quicker convergence with fewer iterations was usually obtained, and this is seen as particularly indicative of a more faithful model. Yet more rigorous surface modelling may be worth developing, but the means of choosing the most appropriate models for different objects also remains a question deserving to be pursued. Copyright ISPRS Numéro de notice : A2001-219 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/S0924-2716(01)00034-X En ligne : https://doi.org/10.1016/S0924-2716(01)00034-X Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21913
in ISPRS Journal of photogrammetry and remote sensing > vol 56 n° 1 (May - June 2001) . - pp 42 - 52[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-01021 SL Revue Centre de documentation Revues en salle Disponible An optimisation approach to cartographic generalisation / Lars Harrie (2001)
Titre : An optimisation approach to cartographic generalisation : doctoral thesis Type de document : Thèse/HDR Auteurs : Lars Harrie, Auteur Editeur : Lund [Suède] : Lund University Année de publication : 2001 Importance : 196 p. Format : 16 x 23 cm ISBN/ISSN/EAN : 978-91-628-4652-7 Note générale : bibliographie
Doctoral thesisLangues : Français (fre) Descripteur : [Termes IGN] base de données orientée objet
[Termes IGN] contrainte de cohérence
[Termes IGN] contrainte géométrique
[Termes IGN] généralisation cartographique
[Termes IGN] généralisation cartographique automatisée
[Termes IGN] méthode des moindres carrés
[Termes IGN] mise à jour de base de données
[Termes IGN] optimisation (mathématiques)
[Termes IGN] programmation par contraintes
[Termes IGN] représentation multiple
[Vedettes matières IGN] GénéralisationIndex. décimale : 37.70 Généralisation Résumé : (auteur) Cartographic generalisation is the process of simplifying a representation to suit the scale and purpose of a map. As such, generalisation has always been a central part in map production. This thesis is a contribution to the ongoing work on automating cartographic generalisation. Two topics are treated: optimisation methods in graphic generalisation, and propagation of updates between cartographic data sets of different scales. To enable an optimisation approach to graphic generalisation several topics are studied. Firstly, requirements are stated for defining a good map. These requirements can act as constraints and control the graphic generalisation process. In this thesis, ten analytical constraints for graphic generalisation are proposed, some for single objects and some for groups of objects. Rules are also established regarding when these constraints should be set up. Secondly, the least-squares method is studied as an approach to finding the optimal solution according to the constraints. Related to this, weighting strategies for the constraints are also discussed. Thirdly, computationally efficient methods are tested, which are especially important for establishing spatial relationships between objects and solving the large normal equation systems. Finally, the optimisation approach has been evaluated visually and quantitatively in mid-scale applications. Mapping organisations have to maintain cartographic data sets of different scales (resolutions). Ideally, mapping organisations should only be concerned with updating the most detailed data set and the updates should automatically be propagated to all other data sets. In this study, a prototype system was created for automatic propagation of updates. This system is integrated in an object-oriented map production software, in which the data sets are stored in a multiple representation database. The rules implemented in the prototype system were gathered from data set specifications and by studying printed map series. The propagation of updates performed by the prototype system was compared with manual propagation performed by a cartographer. Note de contenu : 1- Introduction
2- Cartographic generalisation concepts
3- Spatial concepts
4- Review of generalisation research
5- Summary of the papersNuméro de notice : 17192 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Thèse étrangère Note de thèse : Doctoral thesis : Surveying : Lund University : 2001 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81159 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 17192-01 37.70 Livre Centre de documentation Géomatique Disponible Analysis of refraction influences in geodesy using image processing and turbulence models / Philipp Flach (2001)
Titre : Analysis of refraction influences in geodesy using image processing and turbulence models Type de document : Thèse/HDR Auteurs : Philipp Flach, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2001 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 63 Importance : 175 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-05-5 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie
[Termes IGN] analyse spectrale
[Termes IGN] détecteur à transfert de charge
[Termes IGN] filtre de Wiener
[Termes IGN] instrument de géodésie
[Termes IGN] instrumentation Leica
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle atmosphérique
[Termes IGN] réfraction atmosphérique
[Termes IGN] spectre électromagnétique
[Termes IGN] traitement d'image
[Termes IGN] turbulence
[Termes IGN] variance
[Termes IGN] vidéothéodoliteIndex. décimale : 30.03 Instruments de géodésie Résumé : (Auteur) The propagation path of light in the atmosphere is influenced by inhomogeneities of the refractive index. These refraction effects deteriorate the accuracy of the direction and distance measurements in geodetic applications. As illustrated by two examples in this report, the refraction effects cannot be accurately corrected up to now and, therefore, solutions must be provided which can be implemented into geodetic instruments. The presented approach is based on the determination of the temperature gradient being the decisive influential parameter for angular refraction effects.
In the atmosphere, temperature gradients are related to turbulent thermal exchange processes such as the turbulent sensible heat flux. In order to describe atmospheric turbulence, the applied statistical approach uses the method of spectral analysis which states that the atmospheric turbulent velocity field can be thought to consist of many eddies of different densities. This energy spectrum of turbulence can be modelled using the structure constant of refractive index CJ and the inner scale 10 of turbulence. If these two structure parameters are measured, the temperature gradient is derived from dimensionless profile functions using the so-called Monin-Obukhov similarity description. Hereby, the fact should be kept in mind, that the Monin-Obukhov similarity description and the energy spectrum of turbulence are only valid for vertical temperature gradient profiles in the atmospheric boundary layer.
This research work investigates the determination of the required structure parameter Cn and lo by means of image sensors which can be built into geodetic instruments. To derive the structure parameters CJ and 10 from the acquired image data, the application of appropriate image processing techniques is examined. The evaluation concept is based on angle-of-arrival fluctuations and intensity fluctuations. Angle-of-arrival fluctuations are perceived as high-frequency motions of image patterns grabbed by the sensor, and intensity fluctuations are related to the temporal variation of the gray values of the pixels. As presented in this report, these two effects of optical turbulence can be used to determine the structure parameter Cn and lo. For this purpose, image processing techniques must parameterize both angle-of-arrival fluctuations and intensity fluctuations. Within this research work, the angle-of-arrival fluctuations are modelled by the variance óx characterizing the shifting of image patterns which are located using edge detection algorithms. The intensity fluctuations are modelled by the variance óx characterizing the temporal intensity spectrum of the incoming light beam. In the scope of this research work, the variance óx is provided using digital filter techniques such as the Wiener filter or least-squares template matching.
In order to validate this concept, the video theodolite Leica TM3000V and a digital line scan camera Basler L120 are used as two different imaging systems to acquire image data during various practical field experiments. These field experiments revealed a partial good agreement between the structure parameter CJ and lo obtained by the image sensors and the ones obtained by a reference system (scintillometer). Basically, the method presented here is appropriate to reduce the refraction influence. A decisive advantage of this method is based on the fact that additional sensors are not necessary (except for the image sensors which are built into the instrument). However, as the exemplary comparison of temperature gradients shows at the end of the report, further research work in the scope of the atmospheric boundary layer is still necessary.Numéro de notice : 13062 Affiliation des auteurs : non IGN Autre URL associée : http://dx.doi.org/10.3929/ethz-a-004045114 Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : 10.3929/ethz-a-004045114 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-63.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54863 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13062-01 30.03 Livre Centre de documentation En réserve M-103 Disponible 13062-02 30.03 Livre Centre de documentation En réserve M-103 Disponible Close range photogrammetry and machine vision / Keith B. Atkinson (2001)PermalinkEstimation par moindres carrés / Patrick Sillard (2001)PermalinkEtude des relations spécifiques entre végétation et roches du massif de Ronda par télédétection hyperspectrale AVIRIS (1991) et HYMAP (2000) / Guillaume Hallereau (2001)PermalinkGeomatics for environmental applications, geoENV III, Avignon, France, November 22-24 2000 / Pascal Monestiez (2001)PermalinkIntegrierte Modelle zur physikalischen Interpretation geodätischer Deformationsuntersuchungen / I. Milev (2001)PermalinkIntroduction to modern photogrammetry / E.M. Mikhail (2001)PermalinkParticipation à l'analyse des séries temporelles du système international de référence terrestre ITRS / G. Moujally (2001)PermalinkEstimation et interpolation spatiale / Michel Arnaud (2000)PermalinkInitiation à l'analyse des données / Jean de Lagarde (2000)PermalinkPermalink