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Auteur E. Meier |
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Mitigation of atmospheric perturbations and solid Earth movements in a TerraSAR-X time-series / D. Small in Journal of geodesy, vol 86 n° 4 (April 2012)
[article]
Titre : Mitigation of atmospheric perturbations and solid Earth movements in a TerraSAR-X time-series Type de document : Article/Communication Auteurs : D. Small, Auteur ; A. Schubert, Auteur ; G. Jehle, Auteur ; E. Meier, Auteur Année de publication : 2012 Article en page(s) : pp 257 - 270 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] coin réflecteur
[Termes IGN] GPS en mode différentiel
[Termes IGN] image radar moirée
[Termes IGN] image TerraSAR-X
[Termes IGN] marée terrestre
[Termes IGN] précision géométrique (imagerie)
[Termes IGN] réfraction atmosphérique
[Termes IGN] série temporelleRésumé : (Auteur) The TerraSAR-X (TSX) synthetic aperture radar (SAR) marks the recent emergence of a new generation of spaceborne radar sensors that can for the first time lay claim to localization accuracies in the sub-meter range. The TSX platform’s extremely high orbital stability and the sensor’s hardware timing accuracy combine to enable direct measurements of atmospheric refraction and solid Earth movements. By modeling these effects for individual TSX acquisitions, absolute pixel geolocation accuracy on the order of several centimeters can be achieved without need for even a single tiepoint. A 16-month time series of images was obtained over a fixed test site, making it possible to validate both an atmospheric refraction and a solid Earth tide model, while at the same time establishing the instrument’s long-term stability. These related goals were achieved by placing trihedral corner reflectors (CRs) at the test site and estimating their phase centers with centimeter-level accuracy using differential GPS (DGPS). Oriented in pairs toward a given satellite track, the CRs could be seen as bright “points” in the images, providing a geometric reference set. SAR images from the high-resolution spotlight (HS) mode were obtained in alternating ascending and descending orbit configurations. The highest-resolution products were selected for their small sample dimensions, as positions can be more precisely determined. Based on the delivered product annotations, the CR image positions were predicted, and these predictions were compared with their measured image positions both before and after compensation for atmospheric refraction and systematic solid Earth deviations. It was possible to show that when the atmospheric distortion and Earth tides are taken into account, the TSX HS products have geolocation accuracies far exceeding the specified requirements. Furthermore, this accuracy was maintained for the duration of the 16-month test period. It could be demonstrated that with a correctly calibrated sensor, and after accounting for atmospheric and tidal effects, tiepoint-free geolocation is possible with TSX with an absolute product accuracy of about 5 cm. Numéro de notice : A2012-204 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0515-6 Date de publication en ligne : 24/09/2011 En ligne : https://doi.org/10.1007/s00190-011-0515-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31651
in Journal of geodesy > vol 86 n° 4 (April 2012) . - pp 257 - 270[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2012041 RAB Revue Centre de documentation En réserve L003 Disponible Assessment of the influence of flying altitude and scan angle on biophysical vegetation products derived from airborne laser scanning / F. Morsdorf in International Journal of Remote Sensing IJRS, vol 29 n° 5 (March 2008)
[article]
Titre : Assessment of the influence of flying altitude and scan angle on biophysical vegetation products derived from airborne laser scanning Type de document : Article/Communication Auteurs : F. Morsdorf, Auteur ; O. Frey, Auteur ; E. Meier, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 1387 - 1406 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] altitude du capteur
[Termes IGN] angle d'incidence
[Termes IGN] angle de visée
[Termes IGN] couvert végétal
[Termes IGN] données laser
[Termes IGN] hauteur des arbres
[Termes IGN] instrumentation Toposys
[Termes IGN] Leaf Area Index
[Termes IGN] modèle numérique de terrain
[Termes IGN] parc naturel
[Termes IGN] plan de vol
[Termes IGN] signal laser
[Termes IGN] Suisse
[Termes IGN] télémétrie laser aéroportéRésumé : (Auteur) Airborne Laser Scanning (ALS) has been established as a valuable tool for the estimation of biophysical vegetation properties such as tree height, crown width, fractional cover and leaf area index (LAI). It is expected that the conditions of data acquisition, such as viewing geometry and sensor configuration influence the value of these parameters. In order to gain knowledge about these different conditions, we test for the sensitivity of vegetation products for viewing geometry, namely flying altitude and scanning (incidence) angle. Based on two methodologies for single tree extraction and derivation of fractional cover and LAI previously developed and published by our group, we evaluate how these variables change with either flying altitude or scanning angle. These are the two parameters which often need to be optimized towards the best compromise between point density and area covered with a single flight line, in order to reduce acquisition costs. Our test-site in the Swiss National Park was sampled with two nominal flying altitudes, 500 and 900 m above ground. Incidence angle and local incidence angle were computed based on the digital terrain model using a simple backward geocoding procedure. We divided the raw laser returns into several different incident angle classes based on the flight path data; the TopoSys Falcon II system used in this study has a maximum scan angle of + 7.15°. We compared the derived biophysical properties from each of these classes with field measurements based on tachymeter measurements and hemispherical photographs, which were geolocated using differential GPS. It was found that with increasing flying height the well-known underestimation of tree height increases. A similar behaviour can be observed for fractional cover; its respective values decrease with higher flying height. The minimum distance between first and last echo increases from 1.2 metres for 500 m AGL to more than 3 metres for 900 m AGL, which does alter return statistics. The behaviour for incidence angles is not so evident, probably due to the small scanning angle of the system used. fCover seems to be most affected by incidence angles, with significantly higher differences for locations further away from nadir. As expected, incidence angle appears to be of higher importance for vegetation density parameters than local incidence angle. Numéro de notice : A2008-081 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160701736349 En ligne : https://doi.org/10.1080/01431160701736349 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29076
in International Journal of Remote Sensing IJRS > vol 29 n° 5 (March 2008) . - pp 1387 - 1406[article]Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 080-08031 RAB Revue Centre de documentation En réserve L003 Exclu du prêt LIDAR-based geometric reconstruction of boreal type forest stands at single tree level for forest and wildland fire management / F. Morsdorf in Remote sensing of environment, vol 92 n° 3 (30 August 2004)
[article]
Titre : LIDAR-based geometric reconstruction of boreal type forest stands at single tree level for forest and wildland fire management Type de document : Article/Communication Auteurs : F. Morsdorf, Auteur ; E. Meier, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 353 - 362 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] données lidar
[Termes IGN] forêt boréale
[Termes IGN] hauteur des arbres
[Termes IGN] houppier
[Termes IGN] incendie de forêt
[Termes IGN] lasergrammétrie
[Termes IGN] lutte contre l'incendie
[Termes IGN] reconstruction 3D
[Termes IGN] risque naturel
[Termes IGN] segmentation d'image
[Termes IGN] télémétrie laser aéroportéRésumé : (Auteur) Vegetation structure is an important parameter in fire risk assessment and fire behavior modeling. We present a new approach deriving the structure of the upper canopy by segmenting single trees from small footprint LIDAR data and deducing their geometric properties. The accuracy LIDAR data is evaluated using six geometric reference targets, with the standard deviation of the LIDAR returns on the target being as low as 0.06 m. The segmentation is carried out by using cluster analysis on the LIDAR raw data in all three coordinate dimensions. From the segmented clusters, tree position, tree height, and crown diameter are derived and compared with field measurements. A robust linear regression of 917 tree height measurements yields a slope of 0.96 with an offset of 1 m and the adjusted R 2 resulting at 0.92. However, crown diameter is not well matched by the field measurements, with R2 being as low as 0.2, which is most certainly due to random errors in the field measurements. Finally, a geometric reconstruction of the forest scene using a paraboloid model is carried out using values of tree positsion, tree height, crown diameter, and crown base height.
Copyright ElsevierNuméro de notice : A2004-384 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.05.013 En ligne : https://doi.org/10.1016/j.rse.2004.05.013 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26911
in Remote sensing of environment > vol 92 n° 3 (30 August 2004) . - pp 353 - 362[article]Multi-baseline polarimetric SAR interferometry-first experimental spaceborne and airborne results / O. Stebler in ISPRS Journal of photogrammetry and remote sensing, vol 56 n° 3 (April - June 2002)
[article]
Titre : Multi-baseline polarimetric SAR interferometry-first experimental spaceborne and airborne results Type de document : Article/Communication Auteurs : O. Stebler, Auteur ; E. Meier, Auteur ; D. Nuesch, Auteur Année de publication : 2002 Article en page(s) : pp 149 - 166 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] image radar moirée
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] ligne de base
[Termes IGN] modèle de diffusion du rayonnement
[Termes IGN] Pol-INSAR
[Termes IGN] polarimétrie
[Termes IGN] radar à antenne synthétiqueRésumé : (Auteur) This paper gives an introduction to multi-baseline polarimetric synthetic aperture radar interferometry (Pol-InSAR) and shows experimental results obtained with a spacebome and an airborne SAR system. Conventional InSAR combines two SAR images of the same scene acquired from slightly different viewing angles. Pol-InSAR improves the performance of scalar InSAR by exploiting the wave polarisation, allowing a more sophisticated physical interpretation of SAR interferograms. The interferometric decomposition permits the identification of arbitrary scattering mechanisms in two interferometric SAR images and the optimisation of the interterometric coherence, using the identified mathematically independent phase centres related to these scattering mechanisms. Pol-InSAR is sensitive to the distribution of oriented objects in vegetation layers. It is demonstrated that the calculated scattering mechanisms have different vertical loci that can be related to certain vegetation structures. This technique allows for a more appropriate reconstruction of the quasi-three-dimensional spatial distribution of such scattering processes within natural media. Further, the effect of the baseline on the estimation of these scattering mechanisms is shown for the interferometric decomposition. Finally, the differential interferometric phase is calculated between the associated scattering mechanisms for all interferometric pairs and different polarisation states. Copyright ISPRS Numéro de notice : A2002-092 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/S0924-2716(01)00049-1 En ligne : https://doi.org/10.1016/S0924-2716(01)00049-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22007
in ISPRS Journal of photogrammetry and remote sensing > vol 56 n° 3 (April - June 2002) . - pp 149 - 166[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-02011 SL Revue Centre de documentation Revues en salle Disponible