KEYWORDS: LIDAR, Sensors, 3D image processing, 3D acquisition, Global Positioning System, Semiconductor lasers, Night vision, Defense and security, Nd:YAG lasers, Indium gallium arsenide
The Jigsaw program, sponsored by the Defense Advanced Research Projects Agency (DARPA), will demonstrate a multi-observation concept to identify obscured combat vehicles that cannot be discerned from a single aspect angle. Three-dimensional (3-D) laser radar (ladar) images of a nearly hidden target are collected from several observation points. Image pieces of the target taken from all the data sets are then assembled to obtain a more complete image that will allow identification by a human observer. In this effort a test bed ladar, constructed by the Night Vision and Electronic Sensors Directorate (NVESD), is used to provide three-dimensional (3-D) images in which the voxels have dimensions of the order of centimeters on each side. Ultimately a UAV born Jigsaw sensor will fly by a suspect location while collecting the multiple images. This paper will describe a simulated flight in which 800 images were taken of two targets obscured by foliage. The vehicle mounted laser radar used for the collection was moved in 0.076 meter steps along a 61 meter path. Survey data were collected for the sensor and target locations as well as for several unobscured fiducial markers near the targets, to aid in image reconstruction. As part of a separate DARPA contractual effort, target returns were extracted from individual images and assembled to form a final 3-D view of the vehicles for human identification. These results are reported separately. The laser radar employs a diode pumped, passively Q-switched, Nd:YAG, micro-chip laser. The transmitted 1.06 micron radiation was produced in six micro-joule pulses that occurred at a rate of 3 kHz and had a duration of 1.2 nanoseconds at the output of the detector electronics. An InGaAs avalanche photodiode/amplifier with a bandwidth of 0.5 GHz was used as the receiver and the signal was digitized at a rate of 2 GS/s. Details of the laser radar and sample imagery will be discussed and presented.
An experimental study was undertaken to measure the absolute reflectance of a large number of landmines using a single- mode laser diode operating at approximately 814 nm. Approximately thirty different anti-tank (AT) and anti- personnel (AP) mines were irradiated with a highly polarized laser beam configured in a monostatic geometric arrangement. The in-plane (p) and out-of-plane (s) linear polarization components were measured as a function of incidence angle of the transmitted laser energy. The relative value of the reflected power of each polarization component was calibrated against various reflecting Spectralon panels to obtain an absolute reflectance. This effort is being undertaken in support of an Army Program using an active laser system.
The remotely measured surface vibration signatures of tactical military ground vehicles are investigated for use in target classification and identification friend or foe (IFF) systems. The use of remote surface vibration sensing by a laser radar reduces the effects of partial occlusion, concealment, and camouflage experienced by automatic target recognition systems using traditional imagery in a tactical battlefield environment. Linear Predictive Coding (LPC) efficiently represents the vibration signatures and nearest neighbor classifiers exploit the LPC feature set using a variety of distortion metrics. Nearest neighbor classifiers achieve an 88 percent classification rate in an eight class problem, representing a classification performance increase of thirty percent from previous efforts. A novel confidence figure of merit is implemented to attain a 100 percent classification rate with less than 60 percent rejection. The high classification rates are achieved on a target set which would pose significant problems to traditional image-based recognition systems. The targets are presented to the sensor in a variety of aspects and engine speeds at a range of 1 kilometer. The classification rates achieved demonstrate the benefits of using remote vibration measurement in a ground IFF system. The signature modeling and classification system can also be used to identify rotary and fixed-wing targets.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.