Motion camouflage

The principal form of motion camouflage, and the type generally meant by the term, involves an attacker's mimicking the optic flow of the background as seen by its target.

First discovered in hoverflies in 1995, motion camouflage by minimising optic flow has been demonstrated in another insect order, dragonflies, as well as in two groups of vertebrates, falcons and echolocating bats.

[2][4] When movement is required, one strategy is to minimise the motion signal, for example by avoiding waving limbs about and by choosing patterns that do not cause flicker when seen by the prey from straight ahead.

[2] Cuttlefish may be doing this with their active camouflage by choosing to form stripes at right angles to their front-back axis, minimising motion signals that would be given by occluding and displaying the pattern as they swim.

[5] Disrupting the attacker's perception of the target's motion was one of the intended purposes of dazzle camouflage as used on ships in the First World War, though its effectiveness is disputed.

This is not the same as moving straight towards the target (classical pursuit): that results in visible sideways motion with a readily detectable difference in optic flow from the background.

[14] The biologists Andrew Anderson and Peter McOwan have suggested that anti-aircraft missiles could exploit motion camouflage to reduce their chances of being detected.

Motion camouflage pursuit may therefore be adopted both by predators and missile engineers (as "parallel navigation", for an infinity-point algorithm) for its performance advantages.

[16][17] Swaying behaviour is practised by highly cryptic animals such as the leafy sea dragon, the stick insect Extatosoma tiaratum, and mantises.

These animals resemble vegetation with their coloration, strikingly disruptive body outlines with leaflike appendages, and the ability to sway effectively like the plants that they mimic.

Principle of motion camouflage by mimicking the optic flow of the background. An attacker flies towards a target, choosing its path so that it remains on a line between target and a real point behind the attacker; this path differs from classical pursuit, and is often shorter (as illustrated here). The attacker looms larger as it closes on target, but does not otherwise appear to move.
Animals such as frogs are very good at detecting motion, [ 1 ] making motion camouflage a priority for predators.
Predators such as tigers stalk prey very slowly, to minimise motion cues.
The Australian emperor dragonfly mimics the optic flow of its background using real-point motion camouflage to enable it to approach rivals.
Falcons use infinite-point motion camouflage to close on their prey.
Insect-hunting bats and some missiles follow an infinity-point pursuit path keeping parallel to the target ("Parallel navigation"), for its efficiency rather than for camouflage.