Marine Target Detection Using Dual-polarimetric SAR Imagery

In this study,we provide a summary of research advances in the field of maritime target detection using DP(dualpolarimetric)SAR(Synthetic Aperture Radar)imagery,accomplished during the European and China collaboration in the framework of the Dragon-4 program ID 32235.The main innovative contribution is twofold:(1)We addressed ship detection proposing an improved GP-PNF(Geometrical Perturbation-Polarimetric Notch Filter),termed as IGP-PNF,that is characterized by a new feature vector that includes three new scattering features;(2)We addressed oil platform detection by contrasting singlepolarization SAR methods with polarimetric ones in order to quantify the extra-benefit carried on polarimetric information.The proposed theoretical framework is tested against actual multi-polarization SAR data.In particular,ship detection methods are verified against a Sentinel-1 SAR scene where a large number of ships is present;while,oil platform detection is discussed using Terra SAR-X SAR data.Experimental analysis shows that:(1)The IGP-PNF method performs best in terms of clutter-to-target ratio;(2)Coherent polarimetric information significantly outperforms single-polarization SAR measurements in highlighting targets in challenging cases.

The Taylor Energy Oil Spill:Time-series of PolSAR Data to Support Continuous and Effective Observation

In this study,a large time series of Terra SAR-X Stripmap co-polarized(HH-VV)Synthetic Aperture Radar(SAR)imagery collected over the Taylor Energy oil platform site in the Gulf of Mexico is exploited to investigate this 13 year-long unconventional oil spill.TheσCPDapproach is used to estimate the polluted area along time.In addition,a sensitivity analysis is undertaken to point out the dependence ofσCPDto imaging(noise floor,incidence angle)and environment(sea state)parameters.Experimental results demonstrate thatσCPDcan be effectively used to monitor the Taylor Energy oil spill,estimating the polluted area.For the TSX SAR data avail-ability most dense period(year 2013),a daily spill of about 2.2 km^(2) is observed in average,even though high variability(about 2.0 km^(2))is experienced due to the un-conventional characteristics of the spill.

SAR Azimuth Cut-off to Estimate Wind Speed under High Wind Regimes

In this study,the azimuth cut-off method,typically used for SAR moderate wind speed estimation purposes,is analyzed under high wind regimes.Firstly,the importance of the pixel spacing,the size of the boxes selected for Synthetic Aperture Radar(SAR)image partitioning and the image texture in terms of homogeneities are discussed by considering their influence on the azimuth cut-off(λc)estimation.Secondly,a quality control analysis of the reliability ofλc is carried out by evaluating the distance between the autocorrelation functions(ACF)and their correspondent fittings.This analysis points out the importance of filtering out the unreliable and unfeasibleλc values in order to improve the wind speed estimation.The quality control procedure is based on a x2 test,applied on a large Sentinel-1 A dataset.The soundness of the test is verified by an increment in terms of correlation betweenλc estimations and wind speed values.This approach is,then,applied under high wind regimes,i.e.,tropical cyclones.