| Popis: |
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. |
