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A statistical approach to preprocess and enhance C-band SAR images in order to detect automatically marine oil slicks / Zhour Najoui in IEEE Transactions on geoscience and remote sensing, vol 56 n° 5 (May 2018)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 56 n° 5 (May 2018) . - pp 2554 - 2564 Titre : A statistical approach to preprocess and enhance C-band SAR images in order to detect automatically marine oil slicks Type de document : Article/Communication Auteurs : Zhour Najoui , Auteur ; Serge Riazanoff, Auteur ; Benoit Deffontaines , Auteur ; Jean-Paul Xavier, Auteur Année de publication : 2018 Projets : 1-Pas de projet / Article en page(s) : pp 2554 - 2564 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] bande C [Termes IGN] détection automatique [Termes IGN] image radar moirée [Termes IGN] restauration d'image Résumé : (auteur) The aim of this paper was to propose a new methodology for preprocessing and enhancing C-band synthetic aperture radar (SAR) images for the automatic detection of marine oil slicks. The proposed methodology includes three processing levels: preprocessing, thresholding, and binary cleaning. The first level is to correct the heterogeneity of brightness in SAR images caused by the non-Lambertian reflection of the radar signal on the sea surface. This heterogeneity can be justified by: the distance from the nadir (incidence angle effect), the interaction between wind direction and radar pulse, and the wide swath mode. The second level consists of a thresholding step. The third level is to clean the binary output images from noise residues. Several preprocessing and cleaning methods have been tested and evaluated by a qualification engine that compares the automatically detected patches with a training data set of manually detected dark patches. The training data set includes oil slicks and lookalikes. As a result, the “best” preprocessing method that homogenizes the brightness of C-band SAR scenes and optimizes the automatic detection of marine oil slicks is based on an adaptation to the C-band MODel. As for the cleaning process, the tested morphological methods show that small object removal followed by a morphological closing optimizes the automatic detection of marine oil slicks. Numéro de notice : A2018-238 Affiliation des auteurs : UPEM-LASTIG+Ext (2016-2019) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2017.2760516 Date de publication en ligne : 11/01/2018 En ligne : https://doi.org/10.1109/TGRS.2017.2760516 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90188 [article]

Estimated location of the seafloor sources of marine natural oil seeps from sea surface outbreaks : A new "source path procedure" applied to the northern Gulf of Mexico / Zhour Najoui in Marine and Petroleum Geology, Vol 91 (March 2018)  

Public [article]  inMarine and Petroleum Geology > Vol 91 (March 2018) . - pp 190 - 201 Titre : Estimated location of the seafloor sources of marine natural oil seeps from sea surface outbreaks : A new "source path procedure" applied to the northern Gulf of Mexico Type de document : Article/Communication Auteurs : Zhour Najoui , Auteur ; Serge Riazanoff, Auteur ; Benoit Deffontaines , Auteur ; Jean-Paul Xavier, Auteur Année de publication : 2018 Projets : 3-projet - voir note / Article en page(s) : pp 190 - 201 Note générale : Bibliographie This work is performed as a part of a PhD research program funded by VisioTerra/UPE (Université Paris-Est) and ANRT/CIFRE (N° 2013/1252). Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] fond marin [Termes IGN] HYbrid Coordinate Ocean Model [Termes IGN] image radar moirée [Termes IGN] Mexique (golfe du) [Termes IGN] modèle stochastique [Termes IGN] pétrole Résumé : (Auteur) Marine oil reservoirs are generally characterized on the sea surface by the presence of natural oil seeps (Sea Surface outbreaks - hereafter SSO). The latter are easily evidenced with Synthetic Aperture Radar (SAR) images because of the dampening effect that oil has on the capillary and associated small gravity waves (Bragg waves). The sea surface outbreaks of oil seeps are offset from their source on the seabed (seafloor sources - SFS) by hundreds meters or even kilometres. This displacement all along the sea water column is a function of the upward velocity of the oil droplet size, and the presence of lateral marine currents. This paper proposes a Vertical Drift Model (VDM) that combines both SAR images to get the SSO and the hydrodynamic model (HYCOM) function of the oil droplet size to estimate the SFS. After oil seeps detection from SAR images, the VDM proceeds to a regression in time and space based on the upward velocity of the oil, based on Stokes law, and the hydrodynamic conditions (HYCOM) to estimate the location of the seep source on the seafloor. The upward velocity depends strongly on the unknown droplet size. We propose herein a new VDM method named "sources paths" that allows to estimate the oil seeps sources on the seafloor without a priori knowledge of the oil droplet size by finding, for each oil seep, the seafloor sources corresponding to different diameters. We call "sources path" the line that joins the seafloor sources for an oil seep. The seafloor sources ought to be at the intersection of the maximum sources paths. The methodology has been applied to the northern Gulf of Mexico where the locations of many prolific oil seep sites are well known. A first validation of the source path procedure is that the obtained SFSs correspond to the seafloor sources of oil droplets having the same diameter and seeped at different times. Another validation has been performed through the comparison of SFS locations and those of the outcropping shallow salt. This comparison shows a good correlation and suggests that the oil seeps may be situated above the allochtonous toward autochthonous salt connections. Numéro de notice : A2018-064 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.marpetgeo.2017.12.035 Date de publication en ligne : 04/01/2018 En ligne : https://doi.org/10.1016/j.marpetgeo.2017.12.035 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89404 [article]