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Improved Oil Slick Detection and Classification with Polarimetric SAR

Improved Oil Slick Detection and Classification with Polarimetric SAR. J. Fortuny-Guasch and D. Tarchi DG Joint Research Centre POLINSAR Workshop ESA/ESRIN, Frascati, January 14-16, 2003. Outlook. Background Basic Considerations Study Areas (North Sea and Southern Italy)

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Improved Oil Slick Detection and Classification with Polarimetric SAR

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  1. Improved Oil SlickDetection and Classification with Polarimetric SAR J. Fortuny-Guasch and D. Tarchi DG Joint Research Centre POLINSAR Workshop ESA/ESRIN, Frascati, January 14-16, 2003 Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  2. Outlook • Background • Basic Considerations • Study Areas (North Sea and Southern Italy) • Oil Slick Indicators: • Sea Surface Roughness (Complex Circular Polarization Coherence) • Polarimetric Anisotropy • Example Results • Future Work Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  3. Background • Institutional Project: • Mapping of illicit oil pollution activity in the European Seas and statistical analysis on a yearly basis (Customer is EC DG Env) • Two Competitive Actions: • Rapsodi: Airborne SAR System for oil-spill surveillance • Marsais: Development of SAR analysis and interpretation tools for coastal zone surveillance • Exploratory Research: • Potential Advantages of Polarimetric Imagery Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  4. Basic Considerations • Sea reflectivity due to Bragg scattering from capillary and short gravity waves (VV>HH): • Slicks attenuate these waves and reduce the backscatter (reflectors) • Detection of slicks optimal at: • Small incidence angles • Moderate wind speeds(~3-8 m/s) Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  5. SAR Imagery • NASA/JPL SIR-C L and C-Bands Images (1994) • Multilook Complex (MLC) Quad-Pol Data • Single Image CEOS Format (~100 Mbyte) • Uncompressed Polarimetric Image (~1.2 Gbyte) • High Computational Cost Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  6. Study Areas (1) English Channel Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  7. Study Areas (2) Westerland (Northern Germany) Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  8. Study Areas (3) North Sea Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  9. Study Areas (4) Pantelleria Island Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  10. Surface Roughness • Potential Estimators of Surface Roughness: • Circular Polarization Coherence (CPC) • Srr=(Shh-Svv+2 j Shv)/2; Sll=(Shh-Svv - 2 j Shv)/2 • rrll=<Srr Sll*>/Sqrt[<Srr Srr*><Sll Sll*>] • Polarimetric Anisotropy (Cloude/Pottier Decomposition) • A=(l3-l2)/(l3+l2)wherel1,l2,l3 are the (two smallest) eigenvalues of the averaged coherence matrix <T>=<k k*>,k=[Shh Svv 2 Shv] Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  11. E-Channel, C-Band Data Surface Roughness Retrieval Low Roughness within the Oil Slick at C-Band Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  12. E-Channel, C-Band Data Entropy Alpha Classifier High Anisotropy within the Oil Slick at C-Band Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  13. Westerland, C-Band Data High Anisotropy within the Oil Slick at C-Band Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  14. North Sea, L-Band Data Circular Polarization Basis Improves Ship Detectability LR Basis Anisotropy Always High within the Oil Slick HV Basis Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  15. North Sea, L-Band Data Ship-to-Sea-Clutter Ratio ~7dB Higher with the Circular Polarization Basis LR Basis HV Basis Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  16. Pantelleria Island, L-Band Data Anisotropy Changes within the Oil Slick Humanitarian Security Unit Institute for the Protection and Security of the Citizen

  17. Findings • The analysis of the imagery shows that: • The anisotropy is always higher within the slick area both in L and C-Bands • The estimates given by the CPC are consistent (roughness within the slick area is lower) • Future Work • Establish the applicability range and robustness • Identify alternative slick indicators for Envisat dual-polarized products (HH/VV, HH/HV, VV/HV) • Validation on an extensive set of images Humanitarian Security Unit Institute for the Protection and Security of the Citizen

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