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Airborne GPS photogrammetry in low-altitude applications (Part Two) / Peter Kuntu-Mensah in Surveying and land information systems, vol 61 n° 3 (01/09/2001)
[article]
Titre : Airborne GPS photogrammetry in low-altitude applications (Part Two) Type de document : Article/Communication Auteurs : Peter Kuntu-Mensah, Auteur ; Raymond J. Hintz, Auteur Année de publication : 2001 Article en page(s) : pp 153 - 164 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] aérotriangulation
[Termes IGN] géoréférencement direct
[Termes IGN] GPS-INS
[Termes IGN] ingénierie
[Termes IGN] point de canevasRésumé : (Auteur) The use of GPS to determine camera exposure positions has been shown to drastically reduce and possibly eliminate the number of ground control points required in a photogrammetric aerial triangulation. This notwithstanding, the application of airborne GPS in lowaltitude photogrammetry has been virtually nonexistent. The research described in this paper suggests that airborne GPS can provide measurement accuracies suitable for engineering design and similar applications. Numéro de notice : A2001-164 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21859
in Surveying and land information systems > vol 61 n° 3 (01/09/2001) . - pp 153 - 164[article]Voir aussiRéservation
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Code-barres Cote Support Localisation Section Disponibilité 121-01031 SL Revue Centre de documentation Revues en salle Disponible Airborne GPS photogrammetry comes of age (Part One) / Peter Kuntu-Mensah in Surveying and land information systems, vol 61 n° 2 (01/06/2001)
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Titre : Airborne GPS photogrammetry comes of age (Part One) Type de document : Article/Communication Auteurs : Peter Kuntu-Mensah, Auteur Année de publication : 2001 Article en page(s) : pp 93 - 102 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] aérotriangulation
[Termes IGN] données GPS
[Termes IGN] géoréférencement direct
[Termes IGN] photogrammétrie
[Termes IGN] point d'appuiRésumé : (auteur) The use of the global positioning system (GPS) to determine relative positional data for ground control points in a photogrammetric block adjustment is widely accepted and practiced. On the other hand, using GPS to determine camera exposure positions (airborne GPS, also known as ABGPS) drastically reduces, and possibly eliminates, the number of horizontal and vertical control points needed in aerial triangulation. Given that control point determination is a major time and cost component of any photogrammetric project, it would appear that commercial companies would be quick to implement GPS-derived exposure stations. Furthermore, control points are often on or near roads, making their location by ground-based survey techniques dangerous. In practice, the number of companies using ABGPS is extremely small, perhaps because of the natural uneasiness with the new technology. This paper reports the results of an empirical evaluation of the application of GPS-derived exposure stations for aerial triangulation. The results of this research show that airborne GPS is, indeed, practical and quite feasible with minimum or no ground control. The high accuracy level of current GPS technology meets the accuracy requirements of photogrammetric applications. The results of this research may help resolve any ambivalence about the use of airborne GPS and foster its application in everyday photogrammetric operations. Numéro de notice : A2001-222 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82337
in Surveying and land information systems > vol 61 n° 2 (01/06/2001) . - pp 93 - 102[article]Voir aussiRéservation
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Code-barres Cote Support Localisation Section Disponibilité 121-01021 SL Revue Centre de documentation Revues en salle Disponible Digital image georeferencing from a multiple camera system by GPS-INS / M.M. Mostafa in ISPRS Journal of photogrammetry and remote sensing, vol 56 n° 1 (May - June 2001)
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Titre : Digital image georeferencing from a multiple camera system by GPS-INS Type de document : Article/Communication Auteurs : M.M. Mostafa, Auteur ; K.P. Schwarz, Auteur Année de publication : 2001 Article en page(s) : pp 1 - 12 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] aérotriangulation
[Termes IGN] caméra numérique
[Termes IGN] capteur aérien
[Termes IGN] chambre métrique
[Termes IGN] erreur moyenne quadratique
[Termes IGN] erreur moyenne quadratique altimétrique
[Termes IGN] étalonnage au sol
[Termes IGN] étalonnage en vol
[Termes IGN] géoréférencement direct
[Termes IGN] GPS en mode différentiel
[Termes IGN] GPS-INS
[Termes IGN] image aérienne
[Termes IGN] objet géographique 3D
[Termes IGN] point d'appuiRésumé : (Auteur) In this paper, the development and testing of an airborne fully digital multi-sensor system for digital mapping data acquisition is presented. The system acquires two streams of data, namely, navigation (georeferencing) data and imaging data. The navigation data are obtained by integrating an accurate strapdown inertial navigation system with a differential GPS system (DGPS). The imaging data are acquired by two low-cost digital cameras, configured in such a way so as to reduce their geometric limitations. The two cameras capture strips of overlapping nadir and oblique images. The GPS/INS-derived trajectory contains the full translational and rotational motion of the carrier aircraft. Thus, image exterior orientation information is extracted from the trajectory, during post-processing. This approach eliminates the need for ground control (GCP) when computing 3D positions of objects that appear in the field of view of the system imaging component. Two approaches for calibrating the system are presented, namely, terrestrial calibration and in-flight calibration. Test flights were conducted over the campus of The University of Calgary. Testing the system showed that best ground point positioning accuracy at 1:12,000 average image scale is 0.2 m (RMS) in casting and northing and 0.3 m (RMS) in height. Preliminary results indicate that major applications of such a system in the future are in the field of digital mapping, at scales of 1:5000 and smaller, and in the generation of digital elevation models for engineering applications. Copyright ISPRS Numéro de notice : A2001-216 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/S0924-2716(01)00030-2 En ligne : https://doi.org/10.1016/S0924-2716(01)00030-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21910
in ISPRS Journal of photogrammetry and remote sensing > vol 56 n° 1 (May - June 2001) . - pp 1 - 12[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-01021 SL Revue Centre de documentation Revues en salle Disponible Genauigkeitsuntersuchungen zur GPS/INS-Integration in der Aerophotogrammetrie / Michael Cramer (2001)
Titre : Genauigkeitsuntersuchungen zur GPS/INS-Integration in der Aerophotogrammetrie Titre original : [Recherches de l'exactitude pour l'intégration GPS/INS en photogrammétrie aérienne] Type de document : Thèse/HDR Auteurs : Michael Cramer, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2001 Collection : DGK - C Sous-collection : Dissertationen num. 537 Importance : 120 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-9576-2 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] aérotriangulation
[Termes IGN] centrale inertielle
[Termes IGN] élément d'orientation externe
[Termes IGN] étalonnage de chambre métrique
[Termes IGN] filtre de Kalman
[Termes IGN] géoréférencement direct
[Termes IGN] GPS-INS
[Termes IGN] image aérienne
[Termes IGN] orientation du capteur
[Termes IGN] orientation externe
[Termes IGN] point de vérification
[Termes IGN] précision de localisation
[Termes IGN] prise de vue aérienne
[Termes IGN] recouvrement d'imagesIndex. décimale : 33.30 Photogrammétrie numérique Résumé : (Auteur) Within this thesis different approaches for the direct measurement of exterior orientation elements of airborne sensors using integrated GPS/INS modules are investigated. The main focus is laid on the analysis of the accuracy potential of a commercially available integrated GPS/INS module using the "standard" approach for direct georeferencing : the integration of continuously recorded GPS and INS data in a Kalman filter approach. This method, originally developed for navigation purposes, is compared to a more straightforward strip-wise approach, which allows, in combination with an imaging sensor, the direct orientation determination even for short time intervals and data segments during photogrammetric strips. Beforehand, the basic principles of GPS/INS integration and the different system-characteristics of GPS and INS are summarized.
The two different approaches for GPS/INS integration mentioned before are investigated on their accuracy performance. For the accuracy analysis the GPS/INS module was combined with a standard analogue aerial camera and flown over a well controlled photogrammetric test site. Utilizing the standard approach of indirect image orientation applying the method of aerial triangulation independent exterior orientations for the discrete camera air stations are obtained and can be used for the estimation of the accuracy potential from GPS/INS. For tile tested commercial GPS/INS module the obtained quality of directly measured orientation elements in an operational airborne environment was about ~10cm for the positioning and ~15” for the attitude. Using the GPS/INS exterior orientations for direct georeferencing without ground control an accuracy of about 8-11µm and 15-23µm in image space is obtained for horizontal and vertical components, respectively. Transferring the accuracy on medium scale photo flight from an altitude of about 2000m above ground, object points are determined with an accuracy of 10-20cm for the horizontal and 20-30cm for the vertical coordinates. This accuracy even holds for the photogrammetrically problematic case of single flight lines. The use of stronger image overlap is of positive influence on the quality of object point determination. Using the second approach of strip-wise GPS/INS evaluation in a combined AT approach similar accuracy is obtained from the same data set. Therefore, this approach offers an alternative orientation method for imaging sensors in case of non-continuously recorded INS data.
The accuracy potential of GPS/INS integration is dependent on the quality of the used sensors and the quality of the GPS update information. The influence of the remaining errors in GPS/INS positions and attitudes on the object point determination is related on the actual flying height. For large scale imagery recorded from lower altitudes positioning errors are of major influence, whereas for higher altitudes remaining attitude errors are the main part of the error budget. Additionally, the overall system quality including the GPS/INS orientation components and the imaging sensor is strongly dependent on the correct overall system calibration. Within this context system calibration is not only restricted on the correct determination of the time and spatial eccentricities between the different sensor components but the calibration of the imaging sensor itself is of major importance. Since there is no possibility of subsequent self-calibration in direct georeferencing, every difference between the assumed mathematical model and the true physical environment during data recording will cause errors in object space. Within the analyzed data set scale dependent errors in the vertical coordinate are present. which could be modelled by slightly modifying the camera focal length used for data evaluation.
The obtained empirical accuracy is of major interest for the subsequent operational use of direct georeferencing in a standard photogrammetric environment. Due to this, the GPS/INS orientation accuracy is calculated using different baseline lengths between aircraft and reference station and varying image overlap and block geometry. Additionally, the influence of interpolation errors on varying data rates used for GPS/INS trajectory computations is estimated. Against the background of direct georeferencing using GPS/INS in photogrammetric practice - without ground control in the ideal case - the overall system requirements are discussed. In the final part of this thesis the possible future use of direct GPS/INS orientation measurements in photogrammetric practice is pointed out.Numéro de notice : 27826 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère DOI : sans En ligne : https://www.ifp.uni-stuttgart.de/dokumente/Dissertationen/Cramer_Diss.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=56450 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 27826-02 33.30 Livre Centre de documentation Photogrammétrie - Lasergrammétrie Disponible 27826-01 33.30 Livre Centre de documentation Photogrammétrie - Lasergrammétrie Disponible Investigation and improvement of airborne laser scanning technique for monitoring surface elevation changes of glaciers / E. Favey (2001)
Titre : Investigation and improvement of airborne laser scanning technique for monitoring surface elevation changes of glaciers Type de document : Thèse/HDR Auteurs : E. Favey, Auteur Editeur : Zurich : Institut für Geodäsie und Photogrammetrie IGP - ETH Année de publication : 2001 Collection : IGP Mitteilungen, ISSN 0252-9335 num. 072 Importance : 152 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-906467-32-0 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] Alpes
[Termes IGN] changement climatique
[Termes IGN] géoréférencement direct
[Termes IGN] glacier
[Termes IGN] GPS en mode cinématique
[Termes IGN] GPS en mode différentiel
[Termes IGN] GPS-INS
[Termes IGN] modèle numérique de surface
[Termes IGN] positionnement différentiel
[Termes IGN] Suisse
[Termes IGN] surveillance météorologique
[Termes IGN] télémétrie laser aéroportéIndex. décimale : 30.60 Géodésie spatiale Résumé : (Auteur) Headlines of global warming and melting glaciers predict sustainable climate changes for future generations. How much mass the glaciers actually loose, has been-despite its importance-investigated only for a few glaciers, as in-situ measuring methods are time-consuming and usually under-sampled. Airborne laser scanning is a young technology opening new possibilities for qualitative and quantitative determination of surface elevation changes of glaciers. Its rise was possible through the combination of several modern measuring methods, such as high-precision DGPS positioning in kinematic mode, attitude measurements using inertial systems, and laser distance measurements to non-cooperative targets.
This work investigates the feasibility and possible improvements of the airborne laser scanning technique with respect to the special circumstances of determining surface elevation changes of glaciers. This consists of an error analysis of the method as well as the scrutiny of its limitations, and its application to remote. alpine areas without the need of in-situ measurements.
The key problem consists in bringing together all necessary elements for georeferencing the laser data, where the quality of each contributing part has to be monitored regarding accuracy and systematic effects. The quality of the GPS trajectory can be degraded by various factors like atmospheric refraction. radio frequency interference, or obstruction of satellite visibility. The reliable identification of the integer-valued carrier phase ambiguities can be hindered or even made impossible by such effects. The attitude solution was realized using an inertial measurement unit. A separate attitude solution with lower accuracy using a GPS multi-antenna array was developed and used to control and correct IMU drift and offset errors. A self-calibration procedure for determining boresight misalignment angles was elaborated. The used laser scanning system showed increased blunder effects with low received signal power. An approach for detecting and removing blunder was implemented.
Using the laser scanning solution presented in this work, a height accuracy of 0.3 m could be realized flying over a runway at 500 m above ground. Higher flying height above ground and turbulences impede the realization of this data quality in the mountains; it amounts to about 0.5 m.
In the test area at Unteraargletscher, Bernese Alps, Switzerland, measurements for a temporal analysis were repeatedly made using the laser scanning technique. For the lower parts of Unteraargletscher, digital surface models originating from photogrammetry are available for comparison. The determination of the surface elevation change distribution was shown to be feasible with an accuracy of 0.50 - 0.7m.
The areas covered by airborne laser scanning are located between 2500 and 3400 m above sea level. For the period 1998-1999, a surface elevation increase of 2-4 m was measured. This positive change can be related to the immense amount of snowfall during the winter 98/99. The coverage of Unteraargletscher with measurements of surface elevation change could be completed up to the remote firn areas thanks to the airborne laser scanning technique. It is available for mass balance and flow modeling calculations.Numéro de notice : 13047 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère DOI : 10.3929/ethz-a-004083013 En ligne : http://dx.doi.org/10.3929/ethz-a-004083013 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54857 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13047-01 33.60 Livre Centre de documentation Photogrammétrie - Lasergrammétrie Disponible 13047-02 THESE Livre LASTIG Dépôt en unité Exclu du prêt A multi-sensor system for airborne image capture and georeferencing / M.M.R. Mostafa in Photogrammetric Engineering & Remote Sensing, PERS, vol 66 n° 12 (December 2000)PermalinkPermalink