Case Studies: SAR-based Solutions for Ship Detection

Maritime authorities worldwide require information to detect illegal, unreported, and unregulated fishing vessels. MDA's business development activities have uncovered a growing interest in monitoring of ship traffic and fishing activities. To date eleven major international fishing agreements exist that 167 countries have signed. The Food and Agriculture Organization (FAO) has developed an International Plan of Action of Illegal Fishing, which specifies that vessels involved in fishing activities are to carry vessel monitoring systems (VMS) conforming to national, regional, or international standards; as well as establish and maintain systems for the acquisition and storage of marine data.

MDA Corporation recognized the potential use of RADARSAT-1 synthetic aperture radar (SAR) data for ship detection, early in the RADARSAT-1 program. The two basic approaches used are detection of the ship wake signature and detection of the ship target itself. RADARSAT-2 will not only provide continuity to RADARSAT-1 but will also offer improvements specific to ship detection applications, such as the dual polarization modes available in all RADARSAT-2 beam modes.

This improvement exists as a result of earlier research done using RADARSAT-1 (C-HH) and ERS (C- VV) SAR data. The results showed that ship-sea contrast is higher for HH polarization thus making RADARSAT-1 suitable for target detection. The results also demonstrated that VV polarization on the other hand tends to provide more information about the sea state thus providing better detection of ship wakes (van der Sanden, 2001).

In addition, our experience with CONVAIR data has shown that RADARSAT-2's cross polarized component (VH or HV) will allow for target detection at smaller incidence angles. The HH/HV combination provides optimized target detection over a greater range of incidence angles than RADARSAT-1. The VV/VH combination provides both the target detection (VH) and the ship wake analysis (VV).

Fully polarimetric (Quad-Pol) data will also improve ship target detection and possibly classification. Polarimetric data will not be available for the SCANSAR beam modes so will only be suitable for ship tracking or perhaps surveillance of regions with limited spatial extent, particularly over small areas such as bays and harbours.

As a source of information for detecting ships, RADARSAT-2 will complement existing shore-based radar and airborne approaches to monitoring, as well as law enforcement practices already in place by Naval Agencies/Coast Guards.