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(105K)These GIFs show comparative images from the various MAPS sensors. The left-most GIF shows a lineup of military vehicles in a field with a wooded area on the left. Note that the relative range image provides excellent contrast for distinguishing targets from background, cued by the abrupt height variation and regular shapes of the man-made objects. Note that the gun barrels of the tanks are just distinguishable for some of the targets.
The second GIF shows a similarly arrayed collection of helicopters on an airfield. Note the complementarity of the laser intensity and passive intensity images with regard to the painted "MOORE AAF" insignia on the hangar roof. The relative range channel eliminates all information other than height, effectively reducing the unnecessary detail present in the other two images for the purposes of target identification---hence the painted field markings under the helicopters do not appear in the relative range image.
The third GIF shows passive intensity, laser intensity, and relative range images of a docked ship. Again note the complementary nature of the information provided by the three channels. Using the information from the relative range channel, it is possible to construct a three-dimensional surface plot representation of the scene, as in the 4th GIF, which depicts the relative range image of one of the helicopters from the 2nd GIF and the surface-plot representation of the same data. By combining range, passive, and intensity data in such a surface plot, excellent contrast of the scene can sometimes be achieved.
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(42K) Unlike in the case of the previous GIFs, sometimes targets of interest are not openly located in a field, where relative range contrast with the ground is high. Instead, a target might be immediately surrounded by objects with complicated variations in temperature, reflectance, and height. The complex and distracting image details introduced by such unwanted background objects is termed "clutter". The leftmost GIF shows on the left a range image of a flatbed truck in an open field, where the relative-range contrast and regular structure make it readily identifiable; on the right is a range image of the same truck (at the same orientation) in a wooded area, where the trees act as clutter. The increased difficulty of picking out a target of interest in such conditions is obvious.
One promising technique for combatting clutter is the use of multiple sensors of different types to image the same scene simultaneously; the diversity thus afforded can increase the chances of detecting a hidden target. The second GIF shows a collection of military vehicles deployed amidst clumps of trees and other clutter. Note that the snow-covered man-made targets are difficult to distinguish from the ground snow, trees, and dark patches of thin snowcover in the intensity image. However, in the relative-range image, the regular shapes and abrupt height variation of the five vehicles make them stand out clearly. The relative-range image also eliminates the confusing and unnecessary contrast of the roads from the image. Note that the gun barrels of the tanks are clearly distinguishable in the range image.
In addition to natural clutter, a clever adversary will also employ camouflage techniques to obscure any evidence of prospective targets. Camouflage designed to hide objects from visual perception is not always as successful at fooling other sensors, however, so employing multiple sensors of different kinds can be a useful tactic for detecting hidden objects. The 3rd GIF shows on the left a relative-range image of a tank under camouflage netting. Note that the relative-range measurement does not penetrate the netting for the most part. In the center is the laser intensity image from the same scene; note that the camouflaged tank appears clearly through the netting in this image; even the gun barrel is clearly distinguishable. On the right is a plot of the laser intensity vs. cross-range distance for one line of the linescan, illustrating that the tank is recognizable through the camouflage netting with good contrast---the tank is the central (maximum) peak between the two intensity minima, which represent the dark camouflage netting.
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(97 K)These GIFs were created as part of a study of clutter and camouflage near Presque Isle, Maine. The first image provides ground images of the most prominent targets appearing in the subsequent images: these are an empty logging truck, a loaded logging truck, and the MIT Lincoln Laboratory Test Target (LLTT).
The second image shows the camouflaged LLTT truck on a logging road surrounded by forest clutter. Relative range and laser intensity data are combined in the "Height-sliced intensity" image to provide good target contrast. The "3-D rendering" at bottom is a surface plot of the relative range data with the intensity data added in for better contrast. Note that the combination of the two channels provides some improvement over the relative-range-only image.
The 3rd GIF shows four vehicles on a logging road, surrounded by forest clutter, in passive intensity and 0.85-micron relative-range images. The top-most vehicle is a pickup truck; note the warm engine evident in the passive image. The two center objects are the LLTT and the loaded logging truck, each obscured with camouflage netting. The bottom vehicle is the empty logging truck. Note that all of the vehicles are somewhat difficult to locate in the passive intensity image, and the netted vehicles are effectively hidden. In the relative-range image, the height variation gives good contrast for the unobscured vehicles; the empty logging truck's cab and trailer frame are readily visible. The netted vehicles are still difficult to distinguish, but their presence is clear from the height variation apparent in the relative-range image.
The 4th GIF shows the loaded logging truck (upper vehicle) and the LLTT under winter
camouflage netting (lower object) on a logging road surrounded by forest clutter. The left
image is laser intensity; the right image shows relative range. The loaded logging truck is
readily distinguishable in the relative-range image---note the tapering appearance of the
log cargo, which is loaded with the thick ends of the logs nearest the cab of the truck, so
that the height of the load slopes down toward the back of the truck. The LLTT, which is
effectively concealed under the camouflage netting in the relative-range image, is clearly
distinguishable in the laser intensity image, which penetrates the netting.
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