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Auteur C. Schwiertz |
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Experimente zur GPS-gestützten Aerotriangulation unter besonderer Berücksichtigung systematischer Einflüsse / C. Schwiertz (1994)
Titre : Experimente zur GPS-gestützten Aerotriangulation unter besonderer Berücksichtigung systematischer Einflüsse Titre original : [Expériences pour une aérotriangulation basée sur le GPS en considérant particulièrement les influences systématiques] Type de document : Monographie Auteurs : C. Schwiertz, Auteur Editeur : Munich : Universität der Bundeswehr Année de publication : 1994 Collection : Schriftenreihe des Instituts für Geodäsie, ISSN 0173-1009 num. 48 Importance : 190 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Photogrammétrie spatiale
[Termes IGN] aérotriangulation
[Termes IGN] densité des points
[Termes IGN] GPS en mode cinématique
[Termes IGN] point d'appuiIndex. décimale : 33.40 Photogrammétrie spatiale Résumé : (Auteur) Kinematic GPS-positioning enables the determination of the eccentric positions of exposure during a photo flight. Introducing these positions in an extended bundle adjustment makes it possible to reduce the number of ground control points necessary in classical mode to a minimum. This thesis concentrates on three main topics to reveal various advantages and problems concerning the combined adjustment of photogrammetric data and GPS-positions. In outline, the main results are as follows:
The influence of systematic errors
It is well known that exposure stations tend to compensate errors ill the photogrammetric block. In GPS-controlled blocks the exposure stations are virtually fixed in space. Remaining systematic errors will result in block deformation. The theoretical investigations show that the method of self-calibration becomes more important in this case. On the other hand, a more realistic determination of additional parameters and of the elements of interior orientation would be possible by GPS-supported aerial triangulation.
The datum problem
The datum problem is caused by the fact that GPS-derived positions are related to a global earth fixed coordinate system (e.g. WGS84), but the results of the photogrammetric point determination are preferably wanted ill a regional national reference system. The problem is solved ill GPS-supported aerial triangulation with control points as usual. For the needs of practicality and for the sake of accuracy, it is recommended to use control points and to determine the datum parameters by a combined adjustment. Some examinations using simulated data show that this is possible based only oil one control point. In such a case, additional geometric information -especially height information- would assist in limiting the loss of accuracy.
Mathematical models for GPS-supported aerial triangulation
At the onset of the discussion, different mathematical models for the integration of GPSderived coordinates of the perspective centres ill bundle adjustment are reviewed. These models contain additional parameters for modelling constant and time dependant trends ill GPS-positions.
Furthermore, a new model is presented which allows the formulation of a 'time-dependant' bundle adjustment. The calculation of the camera positions based on the GPS-positions and the recorded times of exposure is integrated in the combined adjustment. In marginal cases, exact knowledge of the times of exposure is no longer necessary.
The main advantage of all these models is that the influence of errors in GPS-data or in time recording can be mitigated during extended bundle adjustment.
The efficiency of GPS-controlled bundle adjustment is demonstrated by the results of two test flights carried out in the year 1988 (Schwabmünchen, photo scale 1:14.000) and 1990 (Hambach, photo scale 1:4.500). The Hambach test flight in particular shows that the positions of exposure eau be determined by kinematic GPS at a tolerance of 2 to 4 cm. Concerning the point determination, it can be established that GPS-supported aerial triangulation with only a few control points is almost as accurate as the conventional method.
Contrary to other test sites, investigated elsewhere, that were located in fairly flat terrain, t lie test area at Hambach shows great differences in height. This caused some problems for height deter mina ion in the CPS-supported mode when only a few control points were used, as there is a high correlation with the focal length computed by self calibration.Numéro de notice : 61670 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=60963 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 61670-01 33.40 Livre Centre de documentation Photogrammétrie - Lasergrammétrie Disponible