08-16-2017, 10:51 PM
Submitted by,
Rohith.S.Jayakumar
Abstract
Active camouflage or adaptive camouflage is a group of camouflage technologies which allow an object to blend into its surroundings by use of panels or coatings capable of altering their appearance, colour, luminance and reflective properties. Active camouflage has the capacity to provide perfect concealment from visual detection.
Active camouflage is a technique for occluding objects to disappear from the observer. Current implementations make assumptions on the viewpoints of both the observer and the camouflaged target. In this work, we present a framework of view-dependent planar scene camouflage. The cameras representing the observer and the occluding object are placed in general positions. The images captured by the object camera are transformed to the observer viewpoint to generate globally consistent visual data for transparent camouflage. Experimental results are presented for real scene images using a projector-camera system.
Active camouflage provides concealment in two important ways:
Firstly, it makes the camouflaged object appear not merely similar to its surroundings, but effectively invisible through the use of mimicry.
Secondly, active camouflage changes the appearance of the object as changes occur in the background. Ideally, active camouflage mimics nearby objects as well as objects as distant as the horizon. It also makes it see through.
Current systems began with a United States Air Force program which placed low-intensity blue lights on aircraft. As night skies are not pitch black, a 100 percent black-coloured aircraft might be rendered visible. By emitting a small amount of blue light, the aircraft blends more effectively into the night sky.
Active camouflage is rumoured to have taken a new turn with the development of the Boeing Bird of Prey, which apparently took the technology further. (The Bird of Prey was a black project and available data is limited.)
Active camouflage is poised to develop at a rapid pace with the development of organic light-emitting diodes (OLEDs) and other technologies which allow for images to be projected onto irregularly-shaped surfaces. With the addition of a camera, an object may not be made completely invisible, but may in theory mimic enough of its surrounding background to avoid detection by the human eye as well as optical sensors. As motion may still be noticeable, an object might not be rendered undetectable under this circumstance but potentially more difficult to hit.
This has been demonstrated with videos of "wearable" displays where the camera could see "through" the wearer. This usually requires knowledge of the relative positions of the observer(s) and the concealed object.
The University of California at Berkeley and the Lawrence Berkeley National Laboratory announced the creation of a meta-material which has a negative refraction index, that is, light doesn't reflect or refract on it. Instead, light bends around the object. It currently works only on microwave frequencies but is expected to work on the visible spectrum as the materials are made smaller. The technology is being funded by the US military.
Holography
Phased array optics (PAO) provides an implementation of optical camouflage. Instead of producing a two dimensional image of background scenery on an object, PAO would use computational holography to produce a three dimensional hologram of background scenery on an object to be concealed. Unlike a two dimensional image, the holographic image would appear to be the actual scenery behind the object independent of viewer distance or view angle.