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Theory and reality of direct georeferencing in national coordinates / Jan Skaloud in ISPRS Journal of photogrammetry and remote sensing, vol 63 n° 2 (March - April 2008)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 63 n° 2 (March - April 2008) . - pp 272 - 282 Titre : Theory and reality of direct georeferencing in national coordinates Type de document : Article/Communication Auteurs : Jan Skaloud, Auteur ; Klaus Legat, Auteur Année de publication : 2008 Article en page(s) : pp 272 - 282 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] correction des altitudes [Termes IGN] correction géométrique [Termes IGN] géoréférencement direct [Termes IGN] GPS-INS [Termes IGN] grande échelle [Termes IGN] orientation du capteur [Termes IGN] orientation externe [Termes IGN] petite échelle Résumé : (Auteur) This paper focuses on the transformation of the sensor's exterior orientation parameters obtained by direct georeferencing (DG) to national reference frames and their subsequent projection for mapping purposes. The required steps are explained and the emphasis is put on the minimization of distortions arising from the curvature of the earth and the inevitable length distortion of the map projection. We recall first the theoretical possibilities of dealing with the vertical distortions due to DG and then introduce a specifically developed technique for their compensation. Afterwards, we demonstrate the influence of such compensation on real examples of small- and large-scale mapping projects. Finally, we offer a comparison with two leading methods and show how these could benefit from extended modeling of the height correction. Copyright ISPRS Numéro de notice : A2008-117 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2007.09.002 En ligne : https://doi.org/10.1016/j.isprsjprs.2007.09.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29112 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-08021	SL	Revue	Centre de documentation	Revues en salle	Disponible

Approximate direct georeferencing in national coordinates / Klaus Legat in ISPRS Journal of photogrammetry and remote sensing, vol 60 n° 4 (June - July 2006)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 60 n° 4 (June - July 2006) . - pp 239 - 255 Titre : Approximate direct georeferencing in national coordinates Type de document : Article/Communication Auteurs : Klaus Legat, Auteur Année de publication : 2006 Article en page(s) : pp 239 - 255 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] coordonnées cartésiennes géocentriques [Termes IGN] élément d'orientation externe [Termes IGN] géoréférencement direct [Termes IGN] GPS-INS [Termes IGN] projection [Termes IGN] transformation de coordonnées Résumé : (Auteur) Direct georeferencing has gained an increasing importance in photogrammetry and remote sensing. Thereby, the parameters of exterior orientation (EO) of an image sensor are determined by GPS/INS, yielding results in a global geocentric reference frame. Photogrammetric products like digital terrain models or orthoimages, however, are often required in national geodetic datums and mapped by national map projections, i.e., in “national coordinates”. As the fundamental mathematics of photogrammetry is based on Cartesian coordinates, the scene restitution is often performed in a Cartesian frame located at some central position of the image block. The subsequent transformation to national coordinates is a standard problem in geodesy and can be done in a rigorous manner–at least if the formulas of the map projection are rigorous. Drawbacks of this procedure include practical deficiencies related to the photogrammetric processing as well as the computational cost of transforming the whole scene. To avoid these problems, the paper pursues an alternative processing strategy where the EO parameters are transformed prior to the restitution. If only this transition was done, however, the scene would be systematically distorted. The reason is that the national coordinates are not Cartesian due to the earth curvature and the unavoidable length distortion of map projections. To settle these distortions, several corrections need to be applied. These are treated in detail for both passive and active imaging. Since all these corrections are approximations only, the resulting technique is termed “approximate direct georeferencing”. Still, the residual distortions are usually very low as is demonstrated by simulations, rendering the technique an attractive approach to direct georeferencing. Copyright ISPRS Numéro de notice : A2006-280 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2006.02.004 En ligne : https://doi.org/10.1016/j.isprsjprs.2006.02.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28007 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-06041	SL	Revue	Centre de documentation	Revues en salle	Disponible

Reliability of direct georeferencing: A case study on practical problems and solutions / Klaus Legat (2006)    

Public contenu dans [Three reports of EuroSDR projects] / European Spatial Data Research EuroSDR (2006)   Titre : Reliability of direct georeferencing: A case study on practical problems and solutions : Final report on phase 2 Type de document : Rapport Auteurs : Klaus Legat, Auteur ; Jan Skaloud, Auteur ; Ronald Schmidt, Auteur Editeur : Dublin : European Spatial Data Research EuroSDR Année de publication : 2006 Collection : EuroSDR official publication, ISSN 0257-0505 num. 51 Importance : pp 169 - 188 Format : 21 x 30 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] centrale inertielle [Termes IGN] correction des altitudes [Termes IGN] étalonnage [Termes IGN] géoréférencement direct [Termes IGN] GPS-INS [Termes IGN] ligne de visée [Termes IGN] orientation du capteur [Termes IGN] source d'erreur [Termes IGN] système de numérisation mobile [Termes IGN] traitement de données Résumé : (auteur) This report studies a practical problem related to the use of GPS/INS technology for sensor direct georeferencing. It is a case study of a specific, yet typical, situation where the performance of a GPS/INS was pronounced unsatisfactory for orientation of an airborne sensor. However, it was in fact not the poor quality of the navigation data but rather numerous disregards occurring in the flight execution and data treatment that have led to this wrong conclusion. The presented analysis reveals the errors committed at different stages of data treatment and quantifies their impact on the sensor exterior orientation. It also explains the remedies employed to mitigate their impact. The recommended procedures are drafted in a summary. Numéro de notice : H2006-003 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Chapître / contribution En ligne : http://www.eurosdr.net/publications/official-publication-no-51-2006 Format de la ressource électronique : URL bulletin Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93670

Documents numériques

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Navigation : principles of positioning and guidance / Bernhard Hofmann-Wellenhof (2003)

Public Titre : Navigation : principles of positioning and guidance Type de document : Guide/Manuel Auteurs : Bernhard Hofmann-Wellenhof, Auteur ; Klaus Legat, Auteur ; M. Wieser, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2003 Importance : 428 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-3-211-00828-7 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] gestion de trafic [Termes IGN] guidage de véhicules [Termes IGN] navigation [Termes IGN] navigation aérienne [Termes IGN] navigation automobile [Termes IGN] navigation inertielle [Termes IGN] navigation terrestre [Termes IGN] orbitographie par GNSS [Termes IGN] positionnement par GNSS [Termes IGN] positionnement par GPS [Termes IGN] radiolocalisation [Termes IGN] trajectographie par GPS [Termes IGN] Wide Area Augmentation System Index. décimale : 30.70 Navigation et positionnement Résumé : (Editeur) Global navigation satellite systems like GPS or the future European Galileo are influencing the world of navigation tremendously. Today, everybody is concerned with navigation even if unaware of this fact. Therefore, the interest in navigation is increasing. This book provides an encyclopedic view of navigation. Fundamental elements are presented for a better understanding of the techniques, methods, and systems used in positioning and guidance. The book is divided into three parts. Besides a historical review and maps, the first part covers mathematical and physical fundamentals. The second part treats the methods of positioning including terrestrial, celestial, satellite-based, inertial, image-based, and integrated navigation. Routing and guidance are the main topics of the third part. Applications on land, at sea, and in the air are considered. The book is designed for students, teachers, and people interested in entering the complex world of navigation. Numéro de notice : 12164 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Manuel de cours Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54567