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The compact polarimetry alternative for spaceborne SAR at low frequency / P. Dubois-Fernandez in IEEE Transactions on geoscience and remote sensing, vol 46 n° 10 Tome 2 (October 2008)
[article]
Titre : The compact polarimetry alternative for spaceborne SAR at low frequency Type de document : Article/Communication Auteurs : P. Dubois-Fernandez, Auteur ; J.C. Souyris, Auteur ; S. Angelliaume, Auteur ; et al., Auteur Année de publication : 2008 Conférence : IGARSS 2007, International Geoscience And Remote Sensing Symposium, sensing and understanding our planet 23/07/2007 27/07/2007 Barcelone Espagne Proceedings IEEE Article en page(s) : pp 3208 - 3222 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] bande L
[Termes IGN] données polarimétriques
[Termes IGN] forêt tempérée
[Termes IGN] image ALOS-PALSAR
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] Landes (40)
[Termes IGN] Pinus pinaster
[Termes IGN] polarimétrie radarRésumé : (Auteur) In spaceborne synthetic aperture radar (SAR), a single-polarization on-transmit offers twice the swath width compared to full polarization. This is linked to SAR system design issues, and, without getting into the technical details deserving by themselves a full paper, we can just mention the swath characteristics of ALOS PALSAR (the Advanced Land Observing Satellite, Phased Array L-Band Synthetic Aperture Radar), reducing from 70 km for the dual-pol mode to 30 km for the full polarization mode. The reduced coverage in the full polarization mode has a harmful impact on the revisit time, which is always a major drive for the Earth-observing community. The options chosen up to now for dual-pol system designs (or single-polarization on-transmit) rely on a linear polarization on-transmit [either horizontal (H) or vertical (V)], with two orthogonal polarizations on-receive. Souyris and Raney in earlier papers proposed more pertinent alternatives for the selection of the transmit polarization leading to a better characterization of the scattering mechanisms. In this paper, the analysis is pursued in more depth by including the effect of the ionosphere on the wave propagation and extending the applications to polarimetric interferometry SAR (PolInSAR). A compact mode is developed where the transmit polarization is circular, whereas the only constraint on the two receiving polarizations is independence. Indeed, the choice of the polarizations of the two receive channels does not matter, as any polarization on-receive can be synthesized from these two measurements. This is, however, not the case for the unique transmit polarization. At a low frequency, where the ionosphere has a significant effect, the circular transmit polarization is the only sensible option, as it provides an effective constant polarization as seen by the scattering surface. This is an essential condition for a meaningful multitemporal analysis. Both the polarimetric SAR applications and the PolInSAR applications in the context of this compact polarimetry (CP) mode are explored. A pseudocovariance matrix can be reconstructed following Souyris' proposed approach for distributed targets and is shown to be very similar to the full polarimetric (FP) covariance matrix. The reconstruction of the cross-polarized Sigma0 is shown to be reliable and to have very low sensitivity to Faraday rotation. A PolInSAR vegetation height inversion for P-band is presented and applied to the CP data with a level of performance that is similar to the one derived from FP (a 1.2-m root-mean-square height error on the ONERA Airborne radar (RAMSES) data over the Landes Forest). A procedure is developed to correct for the ionospheric effects for the PolInSAR acquisition in the FP or CP mode and is assessed on the data simulated from an airborne acquisition. The results demonstrate that the technique is efficient and robust. The calibration of CP data is identified as an important challenge to be solved, and some clues are provided to address the problem. Numéro de notice : A2008-529 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2008.919143 En ligne : https://doi.org/10.1109/TGRS.2008.919143 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29599
in IEEE Transactions on geoscience and remote sensing > vol 46 n° 10 Tome 2 (October 2008) . - pp 3208 - 3222[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 065-08101B RAB Revue Centre de documentation En réserve L003 Disponible The GPS L2C signal: a preliminary analysis of data quality / Rodrigo Figueiredo Leandro in GPS world, vol 19 n° 10 (October 2008)
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Titre : The GPS L2C signal: a preliminary analysis of data quality Type de document : Article/Communication Auteurs : Rodrigo Figueiredo Leandro, Auteur ; R.B. Langley, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 42 - 47 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] longueur d'onde
[Termes IGN] qualité des données
[Termes IGN] signal GPS
[Termes IGN] utilisateur civilRésumé : (Auteur) 56 and counting. That's the number of GPS satellites that have been launched over the past thirty years beginning with the first prototype {Block I) satellite, space vehicle number 1, in February 1978. Ten Block I satellites were successfully launched between 1978 and 1985 to demonstrate the feasibility of GPS. The first satellite of the Block II operational constellation was launched in February 1989. The four year hiatus in launches was due, in part, to the Space Shuttle Challenger disaster as it had been planned to launch the operational satellites using the Shuttle. Following the accident, it was decided to continue with expendable rockets for GPS launches but to switch to the newly designed Delta II rocket. The pace of Block II launches was rapid with five launches of the original Block II design in 1989 and four in 1990 a modified, version of the Block II satellite - the IIA - was develloped, and between 1990 and 1997,19 Block IIAs were launched. The Block II and IIA satellites established the operational GPS constellation. Full operational capability was declared on April 27,1995. A new satellite was developed for replenishing the constellation as the earlier satellites were retired. Following an initial launch failure, twelve of the Block lIR satellites were launched between 1997 and 2004. All of the satellites in the Block I, Block II, Block IIA, and Block llR, constellations transmitted what are now called the legacy signals : tne C/A-code on the L1 frequency of 1575.42 MHz and the P-code on L1 and the L2 frequency of 1227.60 MHz.The P-code has been encrypted to yield the Y-code since January 1994, denying its direct access by most civil users. Since the C/A-code was only transmitted on the L1 frequency, civil users have had to rely on suboptimal semicodeless techniques for the dual-frequency operation necessary for direct cancellation of ionospheric biases. In 1998, Vice-President Al Gore announced that a new civil signal on L2 would be transmitted by future GPS satellites. This new signal-L2C-joined the legacy signals beginning with the launch of modernized Block llR satellite. Six of these blockllR-M satellites have been launched to date.
In this month's column, we'll overview the characteristics of the new L2C signal and take a look at some of the analyses of received signals carried out by a team of researchers from the University of New Brunswick. Copyright Questex Media Group IncNuméro de notice : A2008-397 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29390
in GPS world > vol 19 n° 10 (October 2008) . - pp 42 - 47[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-08101 RAB Revue Centre de documentation En réserve L003 Disponible Advanced studies in strip pair processing of Cartosat-1 data / P.K. Srivastava in Photogrammetric record, vol 23 n° 123 (September - November 2008)
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Titre : Advanced studies in strip pair processing of Cartosat-1 data Type de document : Article/Communication Auteurs : P.K. Srivastava, Auteur ; T. Srinivasan, Auteur ; Amit Gupta, Auteur ; et al., Auteur Année de publication : 2008 Conférence : ISPRS 2007, High-Resolution Earth Imaging for Geospatial Information workshop 29/05/2007 01/06/2007 Hanovre Allemagne Proceedings IEEE Article en page(s) : pp 289 - 304 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie spatiale
[Termes IGN] compensation par bloc
[Termes IGN] image Cartosat-1
[Termes IGN] modèle numérique de surface
[Termes IGN] orthoimage
[Termes IGN] point d'appui
[Termes IGN] qualité d'image
[Termes IGN] restauration d'image
[Termes IGN] spatiotriangulation
[Termes IGN] tâche image d'un point
[Termes IGN] variabilitéRésumé : (Auteur) With the launch of the Indian remote sensing satellite Cartosat-1, an along-track stereoscopic imaging mission of the Indian Space Research Organisation (ISRO), new possibilities for operational availability of high-resolution stereo-imagery from space for the remote sensing and cartography user communities have emerged. The high-resolution stereo data beamed from twin cameras on board the Cartosat-1 mission facilitates topographic mapping up to 1:25 000 scale. The primary advantage of the Cartosat-1 mission is seen in the generation of digital elevation models (DEMs) and the production of ortho-images in an operational set-up. This also facilitates 3D terrain visualisation for very large tracts of land. Stereo Strip Triangulation (SST) is a software system developed and perfected at the Space Applications Centre of ISRO for operational generation of secondary control and appropriate DEMs for subsequent use in the generation of ortho-images. This system has been in use for almost 2 years at the National Remote Sensing Agency in Hyderabad, India, and has generated a wealth of data for use in topographic mapping. An initiative to generate a database of seamless, homogeneous DEMs and associated ortho-image tiles at country level has been undertaken by ISRO. This data-set has been named CartoDEM. The Cartosat-1 data processing team has completed the design and testing of software for the generation of the CartoDEM. This software system has undergone detailed evaluation and currently is in the final stage of development of the operational procedures required to make maximum use of the capabilities of the Cartosat-1 sensors. A data dissemination software system is currently under development. As part of the large-scale evaluation exercises to finalise the specifications of CartoDEM, it is established that with the 2·5 m ground resolution, a base-to-height ratio of 0·62 and with capability to register conjugate points in the stereopair to sub-pixel level, DEMs can be generated at 0·3 arc second intervals, with a height accuracy of 3 to 4 m, over tracts of undulating land mass up to 15 000 km2 with the use of 10 to 20 ground control points. The Cartosat-1 data processing and evaluation team regularly monitors the radiometric quality of images. As part of the radiometric characterisation of sensors, the team computed point spread functions (PSFs) for the two cameras of Cartosat-1. Special filters based on the PSFs then work to improve the radiometric quality of the images. Initial results from these exercises show good promise in image restoration based on PSFs for Cartosat-1. This paper presents a summary of activities and exercises related to (i) Stereo Strip Triangulation, (ii) CartoDEM, (iii) image quality improvement using the PSF-based image restoration and (iv) block adjustment exercises using a COTS software package. Also reported are the results of post-launch experiments, study and evaluation of DEMs vis-à-vis ortho-images from Cartosat-1. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2008-394 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2008.00491.x En ligne : https://doi.org/10.1111/j.1477-9730.2008.00491.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29387
in Photogrammetric record > vol 23 n° 123 (September - November 2008) . - pp 289 - 304[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-08031 RAB Revue Centre de documentation En réserve L003 Disponible Aspects of generating precise digital terrain models in the Wadden Sea from lidar-water classification and structure line extraction / A. Brzank in ISPRS Journal of photogrammetry and remote sensing, vol 63 n° 5 (September - October 2008)
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Titre : Aspects of generating precise digital terrain models in the Wadden Sea from lidar-water classification and structure line extraction Type de document : Article/Communication Auteurs : A. Brzank, Auteur ; Christian Heipke, Auteur ; J. Goepfert, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 510 - 528 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] données lidar
[Termes IGN] extraction de traits caractéristiques
[Termes IGN] lasergrammétrie
[Termes IGN] littoral
[Termes IGN] modèle numérique de terrain
[Termes IGN] Pays-Bas
[Termes IGN] semis de points
[Termes IGN] Wadden, mer desRésumé : (Auteur) The Wadden Sea is a unique habitat formed by the strong influence of tidal currents. Twice a day the area is flooded and falls dry afterwards. Due to the force of tidal streams, strong morphologic changes occur frequently. In order to monitor these changes, high precision digital terrain models (DTMs) are required. Lidar proved to be an adequate technique to deliver highly accurate 3D mass points of the surface and dense spacing. However, water often remains within tidal channels and depressions even at low tide, and near infrared lidar is not able to penetrate the water leading to a point cloud which contains surface and water points. Thus, the standard processing workflow for DTM generation from lidar is not suited for the Wadden Sea. In this article, a new workflow is proposed for DTM generation from lidar data in the Wadden Sea. Two major building blocks of this workflow, namely classification of the water points and structure line detection, are presented in detail. For both tasks suitable algorithms were developed tailored to meet special requirements of mudflat. Lidar measurements from water surfaces are detected by a supervised fuzzy classification using the features height, intensity, and 2D point density. Structure lines are derived through a piecewise reconstruction of the surface from the lidar data with a hyperbolic tangent function. The obtained results show that both methods considerably improve the accuracy of DTMs from lidar data. Copyright ISPRS Numéro de notice : A2008-386 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2008.02.002 En ligne : https://doi.org/10.1016/j.isprsjprs.2008.02.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29379
in ISPRS Journal of photogrammetry and remote sensing > vol 63 n° 5 (September - October 2008) . - pp 510 - 528[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-08051 SL Revue Centre de documentation Revues en salle Disponible Development and testing of a generic sensor model for pushbroom satellite imagery / T. Weser in Photogrammetric record, vol 23 n° 123 (September - November 2008)
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Titre : Development and testing of a generic sensor model for pushbroom satellite imagery Type de document : Article/Communication Auteurs : T. Weser, Auteur ; Franz Rottensteiner, Auteur ; J. Willneff, Auteur ; et al., Auteur Année de publication : 2008 Conférence : ISPRS 2007, High-Resolution Earth Imaging for Geospatial Information workshop 29/05/2007 01/06/2007 Hanovre Allemagne Proceedings IEEE Article en page(s) : pp 255 - 274 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie spatiale
[Termes IGN] Bhoutan
[Termes IGN] capteur en peigne
[Termes IGN] correction géométrique
[Termes IGN] erreur systématique
[Termes IGN] espace image
[Termes IGN] espace objet
[Termes IGN] fonction spline
[Termes IGN] image ALOS-PRISM
[Termes IGN] image Quickbird
[Termes IGN] image SPOT 5
[Termes IGN] Melbourne
[Termes IGN] modélisation géométrique de prise de vue
[Termes IGN] orientation du capteur
[Termes IGN] test de performanceRésumé : (Auteur) A new generic pushbroom sensor model for high-resolution satellite images in which the orbit and attitudes are modelled by splines is presented. Direct observations for the satellite orbits and attitudes provided in imagery metadata files are used to determine the parameters of these splines. As such observations are contaminated by systematic errors, the new sensor model also incorporates error correction for the orbit and attitude angles. Camera model parameter definitions and file formats generally differ between satellite pushbroom scanners, and the system image- to object-space transformation models are not always compatible with a sensor model based on the familiar perspective model applied in photogrammetry. In order to make the new sensor model applicable to a large number of satellite imaging systems, these vendor-specific definitions are first mapped to the definitions of the new sensor model during data import. This is illustrated for QuickBird, SPOT 5 and ALOS PRISM imagery. The model has been extensively tested using imagery from these same three satellites, over test sites in Melbourne and Bhutan. The tests have shown that the new sensor model can produce georeferencing accuracy of 1 pixel and better when biases in orbit and attitude data are compensated. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2008-392 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2008.00489.x En ligne : https://doi.org/10.1111/j.1477-9730.2008.00489.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29385
in Photogrammetric record > vol 23 n° 123 (September - November 2008) . - pp 255 - 274[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 106-08031 RAB Revue Centre de documentation En réserve L003 Disponible Galileo down to the millimeter: analyzing a GIOVE-A-B double difference / Christian Tiberius in Inside GNSS, vol 3 n° 6 (September 2008)PermalinkGeometric integration of aerial and high-resolution satellite imagery and application in shoreline mapping / R. Li in Marine geodesy, vol 31 n° 3 (September - November 2008)PermalinkInterface Web cartographique de visualisation des données pédologiques / H. Le Martret in Le monde des cartes, n° 197 (septembre 2008)PermalinkLarge-scale overview of the summer monsoon over West Africa during the AMMA field experiment in 2006 / Serge Janicot in Annales Geophysicae, vol 26 n° 9 (September 2008)PermalinkMBOC vs BOC (1,1): multipath comparison based on GIOVE-B data / A. Simsky in Inside GNSS, vol 3 n° 6 (September 2008)PermalinkModel investigation about the potential of C-band SAR in herbaceous wetlands flood monitoring / F. Grings in International Journal of Remote Sensing IJRS, vol 29 n° 17-18 (September 2008)PermalinkLa normalisation en information géographique / S. Debard in Le monde des cartes, n° 197 (septembre 2008)PermalinkOnline precise point positioning: a new, timely service from Natural Resources Canada / Y. Mireault in GPS world, vol 19 n° 9 (September 2008)PermalinkPlanification systémique de la conservation de la biodiversité à l'île de la Réunion (océan Indien) / E. Lagabrielle in Revue internationale de géomatique, vol 18 n° 3 (septembre - novembre 2008)PermalinkDes roselières et des hommes / R. Mathevet in Revue internationale de géomatique, vol 18 n° 3 (septembre - novembre 2008)Permalink