2 research outputs found
An alternative approach for calculating the SAR damping ratio of verified oil slicks
Source: https://ieeexplore.ieee.org/xpl/conhome/1000307/all-proceedings.The damping ratio is a calculated feature that
measures the contrast between oil-slicked water and the
open ocean in SAR data. To implement the damping ratio,
the current literature suggests estimating the open water
backscatter by taking strips of undefined width across the
range direction, obtaining the damping ratio as a function
of incidence angle. We show in this paper that the method
proposed in the literature can be improved by instead
sampling open water pixels randomly. The method is
tested on RADARSAT-2 quad-polarimetric SAR imagery
of a verified oil slick acquired during the 2013 NOFO oilon-water exercise conducted in the North Sea. The results
suggest that deviations in the derived damping ratio
encountered by implementing the method proposed in the
literature can be reduced from of order 100 – 10-1 to 10-3
A Sensitivity Study of L-Band Synthetic Aperture Radar Measurements to the Internal Variations and Evolving Nature of Oil Slicks
This thesis focuses on the use of multi-polarization synthetic aperture radar (SAR) for characterization of marine oil spills. In particular, the potential of detecting internal zones within oil slicks in SAR scenes are investigated by a direct within-slick segmentation scheme, along with a sensitivity study of SAR measurements to the evolving nature of oil slicks. A simple, k-means clustering algorithm, along with a Gaussian Mixture Model are separately applied, giving rise to a comparative study of the internal class structures obtained by both strategies. As no optical imagery is available for verification, the within-slick segmentations are evaluated with respect to the behavior of a set of selected polarimetric features, the prevailing wind conditions and weathering processes. In addition, a fake zone detection scheme is established to help determine if the class structures obtained potentially reflect actual internal variations within the slicks. Further, the evolving nature of oil slicks is studied based on the temporal development of a set of selected geometric region descriptors. Two data sets are available for the investigation presented in this thesis, both captured by a full-polarization L-band airborne SAR system with high spatial- and temporal resolution. The results obtained with respect to the zone detection scheme developed supports the hypothesis of the existence of detectable zones within oil spills in SAR scenes. Additionally, the method established for studying the evolving nature of oil slicks is found convenient for accessing the general behavior of the slicks, and simplifies interpretation