Active camouflage

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Cephalopod molluscs such as this cuttlefish can change color rapidly for signaling or to match their backgrounds. Cuttlefish color.jpg
Cephalopod molluscs such as this cuttlefish can change color rapidly for signaling or to match their backgrounds.

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. [1]

Contents

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.

In animals

Counter-illumination camouflage of the firefly squid, Watasenia scintillans uses bioluminescence to match brightness and color of the sea surface above. Squid Counterillumination.png
Counter-illumination camouflage of the firefly squid, Watasenia scintillans uses bioluminescence to match brightness and color of the sea surface above.

Active camouflage is used in several groups of animals including cephalopod molluscs, [2] fish, [3] and reptiles. [4] There are two mechanisms of active camouflage in animals: color change [4] and counter-illumination. [2]

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. [2] Bioluminescence is common among marine animals, so counter-illumination may be widespread, though light has other functions, including attracting prey and signaling. [5] [6]

Color change

Four frames of a peacock flounder show its ability to match its coloration to the sea bed around and beneath it. Peacock Flounder Bothus mancus in Kona.jpg
Four frames of a peacock flounder show its ability to match its coloration to the sea bed around and beneath it.

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. [7] [4] Cephalopod active camouflage has stimulated military research in the United States. [8]

Active camouflage by color change is used by many bottom-living flatfish such as plaice, sole, and flounder that actively copy the patterns and colors of the seafloor below them. [3] For example, the tropical flounder Bothus ocellatus can match its pattern to "a wide range of background textures" [9] in 2–8 seconds. [9] Similarly, the coral reef fish, the seaweed blenny can match its coloration to its surroundings. [10]

In research

Active camouflage provides concealment by making an object not merely generally similar to its surroundings, but effectively invisible with "illusory transparency" through accurate mimicry, and by changing the appearance of the object as changes occur in its background. [1]

Early research

Yehudi lights prototype raised the average brightness of a Grumman Avenger from a dark shape to the same as the sky. Principle of Yehudi Lights with Avenger head-on view.jpg
Yehudi lights prototype raised the average brightness of a Grumman Avenger from a dark shape to the same as the sky.

Military interest in active camouflage has its origins in Second World War studies of counter-illumination. The first of these was the so-called diffused lighting camouflage tested on Canadian Navy corvettes including HMCS Rimouski. This was followed in the United States Army Air Forces with the airborne Yehudi lights project, and trials in ships of the Royal Navy and the US Navy. [11] The Yehudi lights project placed low-intensity blue lights on aircraft. As skies are bright, an unilluminated aircraft (of any color) might be rendered visible. By emitting a small, measured amount of blue light, the aircraft's average brightness better matches that of the sky, and the aircraft is able to fly closer to its target before being detected. [12] Bell Textron filed for a patent on 1/28/2021, # 17/161075 Active Aircraft Visual Cloaking System, that proposes using electroluminescent paint along with an active camera system to project and control a luminescent paint scheme to blend the aircraft exterior structure with the sky.

Possible technologies

Active camouflage may now develop using organic light-emitting diodes and other technologies which allow for images to be projected onto irregularly shaped surfaces. Using visual data from a camera, an object could perhaps be camouflaged well enough to avoid detection by the human eye and optical sensors when stationary. Camouflage is weakened by motion, but active camouflage could still make moving targets more difficult to see. However, active camouflage works best in one direction at a time, requiring knowledge of the relative positions of the observer and the concealed object. [1]

An invisibility cloak using active camouflage by Susumu Tachi. Left: The cloth seen without a special device. Right: The same cloth seen through the half-mirror projector part of the Retro-Reflective Projection Technology An invisibility cloak using optical camouflage by Susumu Tachi.jpg
An invisibility cloak using active camouflage by Susumu Tachi. Left: The cloth seen without a special device. Right: The same cloth seen through the half-mirror projector part of the Retro-Reflective Projection Technology

In 2003 researchers at the University of Tokyo under Susumu Tachi created a prototype active camouflage system using material impregnated with retroreflective glass beads. The viewer stands in front of the cloth viewing the cloth through a transparent glass plate. A video camera behind the cloth captures the background behind the cloth. A video projector projects this image on to the glass plate which is angled so that it acts as a partial mirror reflecting a small portion of the projected light onto the cloth. The retroreflectors in the cloth reflect the image back towards the glass plate which being only weakly reflecting allows most of the retroreflected light to pass through to be seen by the viewer. The system only works when seen from a certain angle. [13]

Phased-array optics would implement active camouflage, not by producing a two-dimensional image of background scenery on an object, but by 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. [14]

Military prototypes

An armoured vehicle fitted with Adaptiv infrared side panels, switched off (left), and on to simulate a large car (right) Adaptiv infrared camouflage demo hiding tank as car.jpg
An armoured vehicle fitted with Adaptiv infrared side panels, switched off (left), and on to simulate a large car (right)

In 2010, the Israeli company Eltics created an early prototype of a system of tiles for infrared camouflage of vehicles. In 2011, BAE Systems announced its Adaptiv infrared camouflage technology. Adaptiv uses about 1000 hexagonal Peltier panels to cover the sides of a tank. The panels are rapidly heated and cooled to match either the temperature of the vehicle's surroundings, or one of the objects in the thermal cloaking system's "library" such as a truck, car or large rock. [16] [15] [17]

In fiction

Active camouflage technology, both visual and otherwise, is a commonly used plot device in science fiction stories. The Star Trek franchise incorporated the concept ("cloaking device"), and Star Trek: Voyager depicts humans using "bio-dampeners" to infiltrate a Borg Cube without the antagonists realizing they are there. [18] The eponymous antagonists in the Predator films also use active camouflage. [19] In many video games, such as the Halo series, [20] [21] [22] Deus Ex: Human Revolution , [23] and the Crysis series, [24] players can obtain and use cloaking devices. [24] In the 2002 James Bond film Die Another Day , Bond's Aston Martin V12 Vanquish is fitted with an active camouflage system. [25]

See also

Related Research Articles

<span class="mw-page-title-main">Camouflage</span> Concealment in plain sight by any means, e.g. colour, pattern and shape

Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the battledress of a modern soldier, and the leaf-mimic katydid's wings. A third approach, motion dazzle, confuses the observer with a conspicuous pattern, making the object visible but momentarily harder to locate, as well as making general aiming easier. The majority of camouflage methods aim for crypsis, often through a general resemblance to the background, high contrast disruptive coloration, eliminating shadow, and countershading. In the open ocean, where there is no background, the principal methods of camouflage are transparency, silvering, and countershading, while the ability to produce light is among other things used for counter-illumination on the undersides of cephalopods such as squid. Some animals, such as chameleons and octopuses, are capable of actively changing their skin pattern and colours, whether for camouflage or for signalling. It is possible that some plants use camouflage to evade being eaten by herbivores.

<span class="mw-page-title-main">Squid</span> Superorder of cephalopod molluscs

A squid is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin.

<span class="mw-page-title-main">Cephalopod</span> Class of mollusks

A cephalopod is any member of the molluscan class Cephalopoda such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology.

<span class="mw-page-title-main">Cloaking device</span> Theoretical device to render objects invisible

A cloaking device is a hypothetical or fictional stealth technology that can cause objects, such as spaceships or individuals, to be partially or wholly invisible to parts of the electromagnetic (EM) spectrum. Fictional cloaking devices have been used as plot devices in various media for many years.

<span class="mw-page-title-main">Invisibility</span> State of a matter that cannot be seen

Invisibility is the state of an object that cannot be seen. An object in this state is said to be invisible. The phenomenon is studied by physics and perceptual psychology.

<span class="mw-page-title-main">Night vision</span> Ability to see in low light conditions

Night vision is the ability to see in low-light conditions, either naturally with scotopic vision or through a night-vision device. Night vision requires both sufficient spectral range and sufficient intensity range. Humans have poor night vision compared to many animals such as cats, dogs, foxes and rabbits, in part because the human eye lacks a tapetum lucidum, tissue behind the retina that reflects light back through the retina thus increasing the light available to the photoreceptors.

<span class="mw-page-title-main">Bioluminescence</span> Emission of light by a living organism

Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria, and terrestrial arthropods such as fireflies. In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from the genus Vibrio; in others, it is autogenic, produced by the animals themselves.

<span class="mw-page-title-main">Photophore</span> Glandular organ that appears as luminous spots on various marine animals

A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors, however unlike an eye it is optimized to produce light, not absorb it. The bioluminescence can variously be produced from compounds during the digestion of prey, from specialized mitochondrial cells in the organism called photocytes, or, similarly, associated with symbiotic bacteria in the organism that are cultured.

<i>Aliivibrio fischeri</i> Species of bacterium

Aliivibrio fischeri is a Gram-negative, rod-shaped bacterium found globally in marine environments. This bacterium grows most effectively in water with high concentrations of salt, around 20g/L, and at temperatures between 24-28°C. This species has bioluminescent properties, and is found predominantly in symbiosis with various marine animals, such as the Hawaiian bobtail squid. It is heterotrophic, oxidase-positive, and motile by means of a single polar flagella. Free-living A. fischeri cells survive on decaying organic matter. The bacterium is a key research organism for examination of microbial bioluminescence, quorum sensing, and bacterial-animal symbiosis. It is named after Bernhard Fischer, a German microbiologist.

<span class="mw-page-title-main">Yehudi lights</span> Active camouflage system prototype for World War II aircraft

Yehudi lights are lamps of automatically controlled brightness placed on the front and leading edges of an aircraft to raise the aircraft's luminance to the average brightness of the sky, a form of active camouflage using counter-illumination. They were designed to camouflage the aircraft by preventing it from appearing as a dark object against the sky.

<span class="mw-page-title-main">Crypsis</span> Aspect of animal behaviour and morphology

In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and mimicry. Crypsis can involve visual, olfactory or auditory concealment. When it is visual, the term cryptic coloration, effectively a synonym for animal camouflage, is sometimes used, but many different methods of camouflage are employed in nature.

<span class="mw-page-title-main">Firefly squid</span> Species of cephalopod also known as the sparkling enope squid

The firefly squid, also commonly known as the sparkling enope squid or hotaru-ika in Japan, is a species of squid in the family Enoploteuthidae. W. scintillans is the sole species in the monotypic genus Watasenia.

<span class="mw-page-title-main">Countershading</span> Camouflage to counteract self-shading

Countershading, or Thayer's law, is a method of camouflage in which an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptiles, birds, fish, and insects, both in predators and in prey.

<span class="mw-page-title-main">Cuttlefish</span> Order of molluscs

Cuttlefish, or cuttles, are marine molluscs of the suborder Sepiina. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of buoyancy.

<span class="mw-page-title-main">Underwater camouflage</span> Camouflage in water, mainly by transparency, reflection, counter-illumination

Underwater camouflage is the set of methods of achieving crypsis—avoidance of observation—that allows otherwise visible aquatic organisms to remain unnoticed by other organisms such as predators or prey.

<span class="mw-page-title-main">Counter-illumination</span> Active camouflage using light matched to the background

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.

<span class="mw-page-title-main">Diffused lighting camouflage</span> Active camouflage system for Second World War ships

Diffused lighting camouflage was a form of active camouflage using counter-illumination to enable a ship to match its background, the night sky, that was tested by the Royal Canadian Navy on corvettes during World War II. The principle was discovered by a Canadian professor, Edmund Godfrey Burr, in 1940. It attracted interest because it could help to hide ships from submarines in the Battle of the Atlantic, and the research project began early in 1941. The Royal Navy and the US Navy carried out further equipment development and trials between 1941 and 1943.

<span class="mw-page-title-main">Adaptiv</span>

Adaptiv is an active camouflage technology developed by BAE Systems AB to protect military vehicles from detection by far infrared night vision devices, providing infrared stealth. It consists of an array of hexagonal Peltier plates which can be rapidly heated and cooled to form any desired image, such as of the natural background or of a non-target object. Its goal is to develop stealth ground vehicles.

<i>Histioteuthis heteropsis</i> Species of squid

Histioteuthis heteropsis, known as the strawberry squid, is a species of small cock-eyed squid. The scientific nomenclature of these squid stems from their set of differently sized eyes, one being small and blue and the other being large and yellow. It is thought that the large eye is used to see objects against dim light, while the smaller eye is more able to view bioluminescent light sources. The squid's vernacular name arose due to its rich red skin pigmentation and the presence of photophores along its body, making it appear like a strawberry with seeds.

<span class="mw-page-title-main">Bio-inspired photonics</span>

Bio-inspired photonics or bio-inspired optical materials are the application of biomimicry to the field of photonics. This differs slightly from biophotonics which is the study and manipulation of light to observe its interactions with biology. One area that inspiration may be drawn from is structural color, which allows color to appear as a result of the detailed material structure. Other inspiration can be drawn from both static and dynamic camouflage in animals like the chameleon or some cephalopods. Scientists have also been looking to recreate the ability to absorb light using molecules from various plants and microorganisms. Pulling from these heavily evolved constructs allows engineers to improve and optimize existing photonic technologies, whilst also solving existing problems within this field.

References

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  2. 1 2 3 "Midwater Squid, Abralia veranyi". Smithsonian National Museum of Natural History. Retrieved 28 November 2011.
  3. 1 2 Sumner, Francis B. (May 1911). "The adjustment of flatfishes to various backgrounds: A study of adaptive color change". Journal of Experimental Zoology. 10 (4): 409–506. doi:10.1002/jez.1400100405.
  4. 1 2 3 Wallin, Margareta (2002). Naturens palett | Hur djur och människor får färg [Nature's Palette | How animals, including humans, produce colors](PDF) (in Swedish). Vol. 1. Bioscience-explained.org. pp. 1–12. Archived from the original (PDF) on 24 June 2020. Retrieved 9 January 2017.
  5. ↑ Young, R.E.; Roper, C.F. (1976). "Bioluminescent countershading in midwater animals: evidence from living squid". Science. 191 (4231): 1046–1048. Bibcode:1976Sci...191.1046Y. doi:10.1126/science.1251214. PMID   1251214.
  6. ↑ Haddock, S. H. D.; et al. (2010). "Bioluminescence in the Sea". Annual Review of Marine Science. 2: 443–493. Bibcode:2010ARMS....2..443H. doi:10.1146/annurev-marine-120308-081028. PMID   21141672.
  7. ↑ Forbes, Peter. Dazzled and Deceived: Mimicry and Camouflage . Yale, 2009.
  8. ↑ Reid, Amanda (2016). Cephalopods of Australia and Sub-Antarctic Territories. CSIRO. p. 7. ISBN   978-1-486-30393-9. Not surprisingly, this aspect of cephalopod biology has become the subject of US military research with millions of dollars currently being poured into studies on cephalopod camouflage.
  9. 1 2 Ramachandran, V. S.; C. W. Tyler; R. L. Gregory; et al. (29 February 1996). "Letters to Nature". Rapid Adaptive Camouflage in Tropical Flounders. 379 (6568): 815–818. Bibcode:1996Natur.379..815R. doi:10.1038/379815a0. PMID   8587602. S2CID   4304531.
  10. ↑ Bester, Cathleen. "Seaweed blenny". Ichthyology. Florida Museum of Natural History. Archived from the original on 20 September 2015. Retrieved 6 January 2015.
  11. ↑ "Naval Museum of Quebec". Diffused Lighting and its use in the Chaleur Bay. Royal Canadian Navy. Archived from the original on 22 May 2013. Retrieved 19 January 2012.
  12. ↑ Bush, Vannevar; Conant, James; Harrison, George (1946). "Camouflage of Sea-Search Aircraft" (PDF). Visibility Studies and Some Applications in the Field of Camouflage. Office of Scientific Research and Development, National Defence Research Committee. pp. 225–240. Archived from the original (PDF) on October 23, 2013. Retrieved 12 February 2013.
  13. ↑ "Light and Dark: The Invisible Man". Time magazine. 18 November 2003. Archived from the original on 18 November 2003. Retrieved 8 January 2022.
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  15. 1 2 "Adaptiv-A Cloak of Invisibility". BAE Systems. 2011. Retrieved 13 June 2012.
  16. ↑ Schechter, Erik (1 July 2013). "Whatever Happened to Counter-Infrared Camouflage?". Popular Mechanics. Retrieved 19 February 2017.
  17. ↑ "BBC News Technology". Tanks test infrared invisibility cloak. BBC. 5 September 2011. Retrieved 27 March 2012.
  18. ↑ Lasbury, Mark E. (24 August 2016). The realization of Star Trek technologies : the science, not fiction, behind brain implants, plasma shields, quantum computing, and more. Switzerland: Springer International Publishing. p. 39. ISBN   978-3-319-40912-2. OCLC   950954032 . Retrieved 30 May 2021.
  19. ↑ Robley, Les Paul (December 1987). "Predator: Special Visual Effects". Cinefantastique.
  20. ↑ Halo 4: The Essential Visual Guide. Dorling Kindersley. 2013. p. 136. ISBN   978-1-4654-1159-4.
  21. ↑ Radcliffe, Doug (2003). Halo: Combat Evolved, Sybex official strategies & secrets. Sybex. p. 27. ISBN   978-0-7821-4236-5.
  22. ↑ Doug Walsh; Phillip Marcus; Rich Hunsinger; Sea Snipers (2010). Halo: Reach, Signature Series Guide. BradyGames. pp. 20, 253. ISBN   978-0744012323.
  23. ↑ Eidos Montréal (23 August 2011). Deus Ex: Human Revolution (Windows, PlayStation 3, Xbox 360, Wii U, Mac OS X). Square Enix.
  24. 1 2 "Crysis 3: Adaptive Warfare". Crysis.com. Crytek. Archived from the original on 13 August 2016. Retrieved 28 July 2016. CLOAK ENGAGED: Vanish in broad daylight with active camouflage.
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