Active camouflage or adaptive camouflage is camouflage that adapts, often rapidly, to the surroundings of an object such as an animal or military vehicle. In theory, active camouflage could provide perfect concealment from visual detection.
Active camouflage is used in several groups of animals, including reptiles on land, and cephalopod molluscs and flatfish in the sea. Animals achieve active camouflage both by color change and (among marine animals such as squid) by counter-illumination, with the use of bioluminescence.
Military counter-illumination camouflage was first investigated during the Second World War for marine use. More recent research has aimed to achieve crypsis by using cameras to sense the visible background, and by controlling Peltier panels or coatings that can vary their appearance.
List of camouflage methods and Animals that can change color
Active camouflage is used in several groups of animals including cephalopod molluscs, fish, and reptiles. There are two mechanisms of active camouflage in animals: color change and counter-illumination.
Counter-illumination
Counter-illumination is camouflage using the production of light to blend in against a lit background. In the sea, light comes down from the surface, so when marine animals are seen from below, they appear darker than the background. Some species of cephalopod, such as the eye-flash squid and the firefly squid, produce light in photophores on their undersides to match the background. Bioluminescence is common among marine animals, so counter-illumination may be widespread, though light has other functions, including attracting prey and signaling.
Color change permits camouflage against different backgrounds. Many cephalopods including octopuses, cuttlefish, and squids, and some terrestrial amphibians and reptiles including chameleons and anoles can rapidly change color and pattern, though the major reasons for this include signaling, not only camouflage. Cephalopod active camouflage has stimulated military research in the United States.
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Invisibility is the state of an object that cannot be seen. An object in this state is said to be invisible (literally, "not visible"). The phenomenon is studied by physics and perceptual psychology. Since objects can be seen by light in the visible spectrum from a source reflecting off their surfaces and hitting the viewer's eye, the most natural form of invisibility (whether real or fictional) is an object that neither reflects nor absorbs light (that is, it allows light to pass through it).
Counter-illumination is a method of active camouflage seen in marine animals such as firefly squid and midshipman fish, and in military prototypes, producing light to match their backgrounds in both brightness and wavelength. Marine animals of the mesopelagic (mid-water) zone tend to appear dark against the bright water surface when seen from below. They can camouflage themselves, often from predators but also from their prey, by producing light with bioluminescent photophores on their downward-facing surfaces, reducing the contrast of their silhouettes against the background.
Military camouflage is the use of camouflage by an armed force to protect personnel and equipment from observation by enemy forces. In practice, this means applying colour and materials to military equipment of all kinds, including vehicles, ships, aircraft, gun positions and battledress, either to conceal it from observation (crypsis), or to make it appear as something else (mimicry). The French slang word camouflage came into common English usage during World War I when the concept of visual deception developed into an essential part of modern military tactics.
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The present simulation case study compares the impact of electric lighting distributions in relation to work-desk location and orientation on work-plane and eye-level illumination within a small private office. The aim of this study is to better understand ...
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