The following paper describes a recent data collection exercise in which the WAR HORSE visible-near-infrared hyperspectral imaging sensor and IRON HORSE short-wave-infrared hyperspectral imaging sensor were employed in the collection of wide-area hyperspectral data sets. A preliminary analysis of the data has been performed and results are discussed.
PHIRST Light is a visible and near-infrared (VNIR) hyperspectral imaging sensor that has been assembled at the Naval Research Laboratory (NRL) using off-the-shelf components. It consists of a Dalsa 1M60 camera mated to a CRI VariSpec liquid crystal tunable filter (LCTF) and a conventional 75mm Pentax lens. This system can be thought of as the modern equivalent of a filter-wheel sensor. Historically, the problem with such sensors has been that images for different wavelengths are collected at different times. This causes spectral correlation problems when the camera is not perfectly still during the collection time for all bands (such as when it is deployed on an airborne platform). However, the PHIRST Light sensor is hard mounted in a Twin Otter aircraft, and is mated to a TrueTime event capture board, which records the precise GPS time of each image frame. Combining this information with the output of a CMIGITS INS/GPS unit permits precise coregistration of images from multiple wavelengths, and allows the formation of a conventional hyperspectral image cube. In this paper we present an overview of the sensor and its deployment, describe the processing steps required to produce coregistered hyperspectral cubes, and show detection results for targets viewed during the Aberdeen Collection Experiment (ACE).
The following paper describes a recent data collection exercise in which the WAR HORSE visible-near-infrared hyperspectral sensor was employed in the collection of wide- area hyperspectral data sets. Two anomaly detection algorithms, Subspace RX (SSRX) ans Gaussian Spectral Clustering (GSC), were used on the data and their performance is discussed.
In recent years the Optical Sciences Division, Naval Research Laboratory (NRL) has been involved in the development of real-time hyperspectral detection, cueing, target location, and target designation capabilities. Under the Dark HORSE program it was demonstrated that a hyperspectral sensor could be used for the autonomous, real- time detection of airborne and military ground targets. This work has culminated in WAR HORSE, an autonomous real-time visible hyperspectral target detection system that has been configured for us on a Predator Unmanned Air Vehicle (UAV). The sensor system provides Predator with the ability to detect manmade objects in areas of natural background. The system consists of a visible hyperspectral imaging sensor, a real-time signal processor, a high-resolution visible line scan camera, an interface and control software application, and a data storage medium. The system is coupled to an on- board GPS/INS to provide target geo-location information and relevant data is transmitted to a ground station using line- of-sight down-link capabilities. The presented paper will provide an overview of the WAR HORSE sensor system hardware components and their integration aboard a Predator UAV. In addition, the results of a recently completed demonstration aboard the Predator UAV will be provided. This demonstration represents the first autonomous real-time hyperspectral target detection system to flown aboard a Predator UAV.