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Auteur Mélanie Arab-Sedze
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Quantification of L-band InSAR coherence over volcanic areas using LiDAR and in situ measurements / Mélanie Arab-Sedze in Remote sensing of environment, vol 152 (September 2014)
[article]
Titre : Quantification of L-band InSAR coherence over volcanic areas using LiDAR and in situ measurements Type de document : Article/Communication Auteurs : Mélanie Arab-Sedze, Auteur ; Essam Heggy, Auteur ; Frédéric Bretar, Auteur ; Daniel Berveiller, Auteur ; Stéphane Jacquemoud, Auteur Année de publication : 2014 Article en page(s) : pp 202 - 216 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image mixte
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] image ALOS-PALSAR
[Termes IGN] image SPOT 5
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] Leaf Area Index
[Termes IGN] Piton de la Fournaise (volcan)
[Termes IGN] propriété diélectrique
[Termes IGN] Réunion, île de la
[Termes IGN] volcanRésumé : (auteur) Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool to monitor large-scale ground deformation at active volcanoes. However, vegetation and pyroclastic deposits degrade the radar coherence and therefore the measurement of 3-D surface displacements. In this article, we explore the complementarity between ALOS–PALSAR coherence images, airborne LiDAR data and in situ measurements acquired over the Piton de La Fournaise volcano (Reunion Island, France) to determine the sources of errors that may affect repeat-pass InSAR measurements. We investigate three types of surfaces: terrains covered with vegetation, lava flows (a′a, pahoehoe or slabby pahoehoe lava flows) and pyroclastic deposits (lapilli). To explain the loss of coherence observed over the Dolomieu crater between 2008 and 2009, we first use laser altimetry data to map topographic variations. The LiDAR intensity, which depends on surface reflectance, also provides ancillary information about the potential sources of coherence loss. In addition, surface roughness and rock dielectric properties of each terrain have been determined in situ to better understand how electromagnetic waves interact with such media: rough and porous surfaces, such as the a′a lava flows, produce a higher coherence loss than smoother surfaces, such as the pahoehoe lava flows. Variations in dielectric properties suggest a higher penetration depth in pyroclasts than in lava flows at L-band frequency. Decorrelation over the lapilli is hence mainly caused by volumetric effects. Finally, a map of LAI (Leaf Area Index) produced using SPOT 5 imagery allows us to quantify the effect of vegetation density: radar coherence is negatively correlated with LAI and is unreliable for values higher than 7.5. Numéro de notice : A2014-812 Affiliation des auteurs : LASTIG MATIS+Ext (2012-2019) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2014.06.011 Date de publication en ligne : 11/07/2014 En ligne : https://doi.org/10.1016/j.rse.2014.06.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89039
in Remote sensing of environment > vol 152 (September 2014) . - pp 202 - 216[article]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]