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Impact de l’anisotropie du milieu dans les études de profilage géographique / Marie Trotta in Revue internationale de géomatique, vol 25 n° 4 (octobre - décembre 2015)
[article]
Titre : Impact de l’anisotropie du milieu dans les études de profilage géographique Type de document : Article/Communication Auteurs : Marie Trotta, Auteur ; Cécile Deprez, Auteur ; Jean-Paul Donnay, Auteur Année de publication : 2015 Article en page(s) : pp 561 - 579 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] anisotropie
[Termes IGN] Belgique
[Termes IGN] densité d'information
[Termes IGN] distance euclidienne
[Termes IGN] données statistiques
[Termes IGN] origine - destination
[Termes IGN] répartition géographique
[Termes IGN] réseau routier
[Termes IGN] zone géographiqueRésumé : (auteur) Cet article a pour objectif d’évaluer le biais introduit par l’usage de la distance euclidienne dans le cadre d’analyses de profilage géographique. Elle procède par une comparaison des distances routières et euclidiennes calculées sur près de 1 000 couples d’origines-destinations (sites de crimes – point d’ancrage du criminel) issus de la base de données de la police fédérale belge. Les comparaisons sont différenciées selon la densité du réseau de voirie (milieux rural et urbanisé) et les paramètres statistiques des distributions résultantes sont exploités dans l’application du modèle de décroissance avec la distance, principal outil de profilage géographique. Numéro de notice : A2015-927 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.3166/RIG.25.561-579 Date de publication en ligne : 24/06/2016 En ligne : https://doi.org/10.3166/RIG.25.561-579 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79729
in Revue internationale de géomatique > vol 25 n° 4 (octobre - décembre 2015) . - pp 561 - 579[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 047-2015041 RAB Revue Centre de documentation En réserve L003 Disponible Depth, anisotropy, and water equivalent of snow estimated by radar interferometry and polarimetry / Silvan Leinss (2015)
Titre : Depth, anisotropy, and water equivalent of snow estimated by radar interferometry and polarimetry Type de document : Thèse/HDR Auteurs : Silvan Leinss, Auteur Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Année de publication : 2015 Collection : Dissertationen ETH num. 23093 Importance : 243 p. Format : 21 x 30 cm Note générale : bibliographie
A thesis submitted to attain the degree of doctor of sciences of ETH ZurichLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] anisotropie
[Termes IGN] image TerraSAR-X
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] MNS TerraSAR & TanDEM-X
[Termes IGN] neige
[Termes IGN] polarimétrie radarRésumé : (auteur) Snow contributes to the water supply of almost one-sixth of the world's population and has a strong influence on the energy balance of the earth. Snow provides water for life but also threatens life in the form of avalanches and flooding due to snow melt. Most of the world's snow cover is located in remote and inaccessible regions, therefore large-scale snow monitoring is only possible with remote sensing techniques. In the entire electromagnetic spectrum, ranging from kilometer long radio waves to ultrashort gamma waves, only three atmospheric spectral windows exit through which satellites can observe the surface of the earth. Two of them, the optical and the infrared window, are often blocked by clouds or atmospheric water vapor. Visible or infrared light, which is reflected at the snow surface, is difficult to be used for derivation of any volumetric information of the snow pack. Active and passive microwave systems, which operate in the radio window, have the potential to obtain volumetric information of snow because microwaves can penetrate the snow cover. The aim of this thesis is to determine snow properties, like snow depth, snow anisotropy, and snow water equivalent, by analyzing phase differences of radar signals reflected from snow covered regions. Current radar systems provide not only the backscatter intensity of an object, but also an object-specific scattering phase. The phase contains information about object properties as well as accurate information about the propagation delay time. In this thesis, phase differences resulting from propagation delays are analyzed with respect to different polarizations, observation times and observation geometries. Based on polarimetric phase differences, a method to determine the depth of fresh snow was developed. The copolar phase difference (CPD) obtained from radar images acquired with vertically and horizontally polarized microwaves by the satellites TerraSAR-X and TanDEM-X were analyzed. Positive phase differences could be explained by a horizontal anisotropy in fresh snow, which results from snow settling. As the phase difference is a volumetric property, the magnitude of the phase difference is roughly proportional to the depth of fresh snow. The validation with snow depth measurements on the ground show that the spatial variability of the depth of fresh snow can be determined with a resolution below 100 m with space-borne sensors like TerraSAR-X. Cold temperatures have been found to decrease observed phase differences due to temperature gradient metamorphism. The observed relation between the CPD and fresh snow, snow settling, and temperature gradient metamorphism provides a contact-less and destruction-free tool to observe the anisotropy, which is a metamorphic state of snow. The measurable dielectric anisotropy is directly linked to the structural anisotropy of snow which is responsible for the mechanical stability as well as the thermal conductivity of the snow pack. This makes the anisotropy relevant for the energy balance of snow and snow covered soil. In order to measure the anisotropy, a rigorous electromagnetic model was developed which provides a parameter free link between three-dimensional two-point correlation functions of the microstructure of snow, the effective permittivity tensor, and the macroscopically measured copolar phase difference. For verification of the model, four years of ground-based radar data, acquired by the SnowScat instrument in Sodankylä, Finland, were analyzed with respect to the frequency and incidence angle dependence of the copolar phase. Computer tomography data were used for validation of the anisotropy determined from the copolar phase difference measured by SnowScat. The unique dataset of the currently longest time series of anisotropy measurements provides a new basis for improvement of existing snow models. Four years of anisotropy data were used to develop and validate a thermodynamic snow model based on meteorological input data. The model consists of three terms which describe snow settling, temperature gradient metamorphism, and relaxation based on isotropic water vapor transport. The model was calibrated by balancing the three terms in order to reproduce the measured anisotropy time series. The results of the model, vertically resolved anisotropy pro les of the snow pack, were validated with anisotropy pro les determined by computer tomography. In comparison to the anisotropy, which determines specific properties of the snow volume, the snow water equivalent (SWE) determines how much water is stored in the snow pack. Differential interferometry, where the phase difference of two radar acquisitions separated by a certain time is analyzed, is a promising tool to determine SWE. However, temporal decorrelation of the phase signal is a major drawback of this technique. A decorrelation time of a few days has been observed in space-borne acquisitions from TerraSAR-X which prevents any successful SWE determination. However, using SnowScat as a ground based radar interferometer, it was possible for the first time to measure the accumulation of SWE during four entire winter seasons. A multi-frequency phase unwrapping technique was used for reconstruction of phase wraps which occurred due to intense snow precipitation. The study was performed at exceptionally high frequencies in the X- and Ku-band and with a very high temporal resolution of only 4 hours. The successful demonstration of differential interferometry to determine SWE raises hope to apply the demonstrated technique on data of future radar satellites which operate at longer repeat times of a few days and lower frequencies of a few GHz. Both methods, the CPD analysis as well as differential interferometry, cannot be vi applied for wet snow. Microwave penetration into wet snow is generally small and most of the reflected energy results from scattering at the snow surface. This is interesting for single-pass SAR interferometry, where phase differences are compared, which are measured by two SAR-sensors which simultaneously observe the same scene with slightly different angles. Single-pass SAR interferometry can provide accurate surface models at a horizontal resolution of a few meters. The difference between two digital elevation models (DEM), one obtained during snow free conditions and one obtained during the onset of snow melt, can therefore provide direct information about snow depth. DEM differencing was applied on TanDEM-X acquisitions from spring and autumn and snow depths maps were obtained which agree with the snow- depth-maps provided by the Institute for Snow and Avalanche Research, SLF. A key requirement for successful snow depth estimation is that the snow surface can be recognized as wet. As the backscatter intensity decreases significantly during snow melt, wet snow detection is straight forward and the total accumulated snow depth of wet spring snow can be determined. This thesis shows that the analysis of the phase signal contained in radar acquisitions provides a broad spectrum of information about the snow pack. The developed method for anisotropy determination provides not only a unique opportunity to improve snow models, but also a method to globally sense the metamorphic state of snow. The currently longest radar-derived time series of SWE measurements raise hope to apply differential interferometry for global SWE determination of dry snow. The shown accuracy for snow depth determination from high frequency, interferometric, single-pass SAR systems demonstrates that such systems are important missions for monitoring changes in snow depth and ice thickness in remote alpine and polar regions in order monitor changes of the global distribution of fresh water stored in the form of ice or snow. Numéro de notice : 17199 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Note de thèse : doctoral thesis : Sciences : ETH Zurich : 2015 En ligne : http://dx.doi.org/10.3929/ethz-a-010603517 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81170 The Normalization of surface anisotropy effects present in SEVIRI reflectances by using the MODIS BRDF method / Simon Richard Proud in IEEE Transactions on geoscience and remote sensing, vol 52 n° 10 tome 1 (October 2014)
[article]
Titre : The Normalization of surface anisotropy effects present in SEVIRI reflectances by using the MODIS BRDF method Type de document : Article/Communication Auteurs : Simon Richard Proud, Auteur ; Qian Zhang, Auteur ; Crystal Schaaf, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 6026 - 6039 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] anisotropie
[Termes IGN] distribution du coefficient de réflexion bidirectionnelle BRDF
[Termes IGN] image Aqua-MODIS
[Termes IGN] image MSG-SEVIRI
[Termes IGN] image Terra-MODIS
[Termes IGN] rayonnement proche infrarougeRésumé : (Auteur) A modified version of the MODerate resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) algorithm is presented for use in the angular normalization of surface reflectance data gathered by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) aboard the geostationary Meteosat Second Generation (MSG) satellites. We present early and provisional daily nadir BRDF-adjusted reflectance (NBAR) data in the visible and near-infrared MSG channels. These utilize the high temporal resolution of MSG to produce BRDF retrievals with a greatly reduced acquisition period than the comparable MODIS products while, at the same time, removing many of the angular perturbations present within the original MSG data. The NBAR data are validated against reflectance data from the MODIS instrument and in situ data gathered at a field location in Africa throughout 2008. It is found that the MSG retrievals are stable and are of high-quality across much of the SEVIRI disk while maintaining a higher temporal resolution than the MODIS BRDF products. However, a number of circumstances are discovered whereby the BRDF model is unable to function correctly with the SEVIRI observations-primarily because of an insufficient spread of angular data due to the fixed sensor location or localized cloud contamination. Numéro de notice : A2014-478 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2013.2294602 En ligne : https://doi.org/10.1109/TGRS.2013.2294602 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74059
in IEEE Transactions on geoscience and remote sensing > vol 52 n° 10 tome 1 (October 2014) . - pp 6026 - 6039[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 065-2014101A RAB Revue Centre de documentation En réserve L003 Disponible An advanced photogrammetric method to measure surface roughness: Application to volcanic terrains in the Piton de la Fournaise, Reunion Island / Frédéric Bretar in Remote sensing of environment, vol 135 (August 2013)
[article]
Titre : An advanced photogrammetric method to measure surface roughness: Application to volcanic terrains in the Piton de la Fournaise, Reunion Island Type de document : Article/Communication Auteurs : Frédéric Bretar, Auteur ; Mélanie Arab-Sedze, Auteur ; J. Champion, Auteur ; Marc Pierrot-Deseilligny , Auteur ; Essam Heggy, Auteur ; Stéphane Jacquemoud, Auteur Année de publication : 2013 Article en page(s) : pp 1 - 11 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] anisotropie
[Termes IGN] appariement d'images
[Termes IGN] lave
[Termes IGN] microtopographie
[Termes IGN] Piton de la Fournaise (volcan)
[Termes IGN] Réunion, île de la
[Termes IGN] rugosité
[Termes IGN] volcanRésumé : (auteur) We present a rapid in situ photogrammetric method to characterize surface roughness by taking overlapping photographs of a scene. The method uses a single digital camera to create a high-resolution digital terrain model (pixel size of ~1.32 mm) by means of a free open-source stereovision software. It is based on an auto-calibration process, which calculates the 3D geometry of the images, and an efficient multi-image correlation algorithm. The method is successfully applied to four different volcanic surfaces—namely, a′a lava flows, pahoehoe lava flows, slabby pahoehoe lava flows, and lapilli deposits. These surfaces were sampled in the Piton de la Fournaise volcano (Reunion Island) in October, 2011, and displayed various terrain roughnesses. Our in situ measurements allow deriving digital terrain models that reproduce the millimeter-scale height variations of the surfaces over about 12 m2. Five parameters characterizing surface topography are derived along unidirectional profiles: the root-mean-square height (ξ), the correlation length (Lc), the ratio Zs = ξ2/Lc, the tortuosity index (τ), and the fractal dimension (D). Anisotropy in the surface roughness has been first investigated using 1-m-long profiles circularly arranged around a central point. The results show that Lc, Zs and D effectively catch preferential directions in the structure of bare surfaces. Secondly, we studied the variation of these parameters as a function of the profile length by drawing random profiles from 1 to 12 m in length. We verified that ξ and Lc increase with the profile length and, therefore, are not appropriate to characterize surface roughness variation. We conclude that Zs and D are better suited to extract roughness information for multiple eruptive terrains with complex surface texture. Numéro de notice : A2013-791 Affiliation des auteurs : LASTIG MATIS+Ext (2012-2019) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2013.03.026 Date de publication en ligne : 10/04/2013 En ligne : http://dx.doi.org/10.1016/j.rse.2013.03.026 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80084
in Remote sensing of environment > vol 135 (August 2013) . - pp 1 - 11[article]Motion blur detection in aerial images shot with channel-dependent exposure time / Lâmân Lelégard (2010)
contenu dans Photogrammetric computer vision and image analysis, ISPRS Commission 3 symposium, Saint-Mandé, 1-3 septembre 2010, volume 1. Papers accepted on the basis of peer-reviewed full manuscripts / Nicolas Paparoditis (2010)
Titre : Motion blur detection in aerial images shot with channel-dependent exposure time Type de document : Article/Communication Auteurs : Lâmân Lelégard , Auteur ; Mathieu Brédif , Auteur ; Bruno Vallet , Auteur ; Didier Boldo , Auteur Editeur : International Society for Photogrammetry and Remote Sensing ISPRS Année de publication : 2010 Conférence : PCV 2010, ISPRS - Commission 3 symposium Photogrammetric computer vision and image analysis 01/09/2010 03/09/2010 Saint-Mandé France ISPRS OA Archives Importance : pp 180 - 185 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] anisotropie
[Termes IGN] détection automatique
[Termes IGN] image aérienne
[Termes IGN] transformation de FourierRésumé : (Auteur) This paper presents a simple yet efficient approach for automatic blur detection in aerial images provided by a multi-channel digital camera system. The blur in consideration is due to the airplane motion and causes anisotropy in the Fourier Transform of the image. This anisotropy can be detected and estimated to recover the characteristics of the motion blur, but one cannot disambiguate the anisotropy produced by a motion blur from the possible spectral anisotropy of the underlying sharp image. The proposed approach uses a camera with channel-dependent exposure times to address this issue. Under this multi-exposure setting, the motion blur kernel is scaled proportionally to the exposure-time, whereas the phase differences between the underlying sharp colour channels are assumedly negligible. We show that considering the phase of the ratio of the Fourier Transforms of two channels enhances blur detection. Results obtained on 2000 images confirm the operational efficiency of our method. Numéro de notice : C2010-005 Affiliation des auteurs : MATIS+Ext (1993-2011) Thématique : IMAGERIE Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : sans En ligne : https://www.isprs.org/proceedings/XXXVIII/part3/a/pdf/180_XXXVIII-part3A.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65060 Urban-trees extraction from Quickbird imagery using multiscale spectex-filtering and non-parametric classification / Y.O. Ouma in ISPRS Journal of photogrammetry and remote sensing, vol 63 n° 3 (May - June 2008)PermalinkUse of HRSC-A for sampling bidirectional reflectance / Antero Kukko in ISPRS Journal of photogrammetry and remote sensing, vol 59 n° 6 (November 2005)PermalinkComment reproduire le MNT d'une rivière ensablée ? / B. Federici in Géomatique expert, n° 44 (01/06/2005)PermalinkA simple anisotropic model of the covariance function of the terrestrial gravity field over coastal areas / Jonathan Chenal in Newton's bulletin, n° 2 (December 2004)PermalinkDiscrimination potential of X-band polarimetric SAR data / Nicolas Baghdadi in International Journal of Remote Sensing IJRS, vol 25 n° 22 (November 2004)PermalinkGlobal land ice measurements from space (GLIMS) : remote sensing and GIS investigations of the Earth's cryosphere / M.P. Bishop in Geocarto international, vol 19 n° 2 (June - August 2004)PermalinkVegetation canopy anisotropy at 1.4 GHz / B.K. Hornbuckle in IEEE Transactions on geoscience and remote sensing, vol 41 n° 10 (October 2003)PermalinkModélisation des effets bidirectionnels de la réflectances de surface pour la normalisation de données satellitaires de télédétection / Jean-Louis Roujean (1991)PermalinkModelling planetary bidirectional reflectance over land / R.T. Pinker in International Journal of Remote Sensing IJRS, vol 11 n° 1 (January 1990)PermalinkWind-directional effects on the hydrodynamic modulation of microwave radar images of ocean waves / F.J. Ocampo-Torres in International Journal of Remote Sensing IJRS, vol 10 n° 8 (August 1989)Permalink