Detection of Spatially Unresolved (Nominally Sub-Pixel) Submerged and Surface Targets Using Hyperspectral Data

Due to the United States' dependency on maritime travel, the proliferation of efficient and inexpensive naval mines poses a tremendous risk. Current mine countermeasure (MCM) technologies have a narrow field of view, preventing timely, wide-area searches. These technologies require the operator to be in proximity to the targets, a dangerous scenario made worse when in denied territory. In an effort to mitigate these risks, the use of an airborne hyperspectral sensor is proposed. The operational ability of a hyperspectral sensor to detect sub-pixel surface and submerged mines in non-littoral environments was evaluated using two common anomaly detectors: Mixture Tuned Matched Filtering (MTMF) and Reed-Xiaoli (RX). Due to the unavailability of the DoD's Spectral Infrared Imaging Technology Testbed (SPIRITT), ProSpecTIR-VS3, a sensor similar spatially and spectrally to SPIRITT was flown over a Navy test range offshore California. This experiment included three surface and three submerged targets, each with a 0.8 meter diameter. The spatial resolution of the images is dependent on the altitude of the sensor. In an effort to collect both a high spatial resolution and a low spatial resolution data set, two flight altitudes were planned. The high spatial resolution collection altitude was approximately 410 meters and the low spatial resolution altitude was approximately 800 meters. The spatial resolutions of the collections were 0.5 and 1.0 meters, respectively. This allowed for both a resolved and an unresolved analysis. While both anomaly detection techniques were found to have their flaws, the success of the study is in proving the usefulness of hyperspectral data for sub-pixel mine detection.