SAR Tomography for Target/Feature Detection in Foliated Regions

SAR target/feature detection can be divided into to separate aspects: 1) achieving sufficient energy on target for detection; and 2) discriminating the target from the clutter. Let's assume that there is sufficient target return to overcome the thermalnoise floor. Then target detection is solely dependent upon separating the target from the forest clutter. VSAR offers significant benefits for enhanced imagery through clutter rejection, enhanced target definition. These enhancements enable improveddetection of concealed targets, improved characterization of targets, true bare earth mapping under foliage, and characterization of foliage distribution. Essex has obtained results by coherently combining multiple SAR data collects. These collects wereseparated in elevation, azimuth, or both. VSAR algorithms have been incorporated into Essex SAR processing and visualization software packages, and have been demonstrated at UHF FOPEN frequencies. Extensions to other radar bands and platforms couldprovide new ways to recognize and characterize weak or partially concealed targets, or to profile scenes with large vertical relief. Essex has developed and integrated these VSAR capabilities into a platform-independent processing suite with a Java GUIrunning on Linux, Irix, and Windows. These techniques have been validated using data collected with the DARPA FOPEN ATD system at Camp Navajo (2001). The foliage penetration capabilities offered by the VSAR processing approach offers a significantbenefit for several military ACTD programs as well as commercial terrain and infrastructure mapping appications. In addition, these techniques also relax the geometry constraints associated with the collection process for existing operational systems.Currently, the RadarSAT is constrained to collecting repeat pass pairs suitable for terrain mapping approximately every 21 days. The VSAR techniques proposed should improve that to every 2-3 days with better accuracy.