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TitleOptimization of the degree of polarization for enhanced ship detection using polarimetric RADARSAT-2
AuthorTouzi, R; Hurley, J; Vachon, P W
SourceIEEE Transactions on Geoscience and Remote Sensing (Institute of Electrical and Electronics Engineers) vol. 53, no. 10, 7118674, 2015 p. 5403-5424,
Alt SeriesNatural Resources Canada, Contribution Series 20150424
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Mediapaper; on-line; digital
File formatpdf
Subjectsgeophysics; Science and Technology; remote sensing
ProgramRemote Sensing Science
Released2015 06 05
AbstractThe scattered wave is represented in terms of two independent and rotation invariant parameters: the degree of polarization (DoP) and the total scattered intensity R0. The scattered wave polarization signature is introduced as a convenient graphical representation of the variations of the two scattered wave observable parameters as a function of the transmitting antenna polarization. It is shown that the signature of the DoP and the total scattered intensity (R0) provide information on ocean and ship scattering that is complementary to that provided by the conventional received wave intensity polarization signature. While R0 polarization signature of the ocean's Bragg scattering is sensitive to wind speed and synthetic aperture radar illumination angle, the DoP polarization signature appears to depend mainly on ocean surface roughness. The large dynamic range and low pedestal height of ship DoP polarization signature, in comparison with that of the ocean, favors the use of DoP for ship detection in comparison with R0. Optimization of the scattered wave parameters appears to be a convenient tool for efficient ship detection. The scattered wave optimization technique introduced by R. Touzi et al. in the nineties, is reconsidered and applied for enhanced ship detection. It is shown that the excursion of DoP, delta-p, and the minimum DoP, pmin, permits a significant improvement in ship-sea contrast in comparison with conventional (i.e., scalar) single channel polarizations (HH, VV, and HV). The additional information provided by the maximum DoP, pmax solves for ship ambiguities with land targets. Quantification of the ship-ocean contrast is reconsidered in the context of nonstationary ship signal. The ship peak signal quantification appears to be the most suitable method for accurate measurement of ship-ocean contrast in the presence of a nonstationary ship signal. The local pmin performs better than the peak of delta-p and single polarizations (HH, VV, and HV). The added value of polarimetric RS2 information for ship detection is demonstrated using wide swath (50 km) polarimetric RADARSAT-2 data collected at 29° and 40° incidence angle over vessels (validated with Automatic Identification System data) in the Strait of Georgia, near Vancouver, Canada.
Summary(Plain Language Summary, not published)
Maritime monitoring and surveillance using single and linear dual-polarisation Synthetic Aperture Radar (SAR) modes have been extensively studied using RADARSAT-1 and ENVISAT ASAR data, demonstrating promising results for ship detection and oil-spill identification. However, it is now known that the performance of single and dual-polarization SAR over wide swaths can be ineffective for small vessels, and there is an urgent requirement for earth observation sensors permitting an improved detection of small vessels. In this study, an advanced method is introduced for ship detection using polarimetric RADARSAT-2. It is shown that the new method, which fully exploits the added value of polarimetric information for ship detection, permits a significant enhancement of small vessels in comparison with conventional single polarization HH, HV and VV modes, as well as with dual-polarization HH-HV, VV-VH and Compact SAR.

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