Many animals are highly
sensitive to motion; for example,
frogs readily detect small moving dark spots but ignore stationary ones. Therefore, motion signals can be used to defeat camouflage. All the same, the conspicuousness of motion raises the question of whether and how motion itself could be camouflaged. Several mechanisms are possible. s such as
tigers stalk prey very slowly, to minimise motion cues.
Stealthy movements One strategy is to minimise actual motion, as when
predators such as
tigers stalk prey by moving very slowly and stealthily. This strategy effectively avoids the need to camouflage motion.
Minimising motion signal 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.
Disrupting perception of motion in motion camouflage hunting pose. The predator creates a "passing-stripe" pattern on its front, with two of its arms outstretched, reducing its appearance of looming larger as it approaches its crab prey.
Mimicking optic flow of background dragonfly mimics the optic flow of its background using real-point motion camouflage to enable it to approach rivals. Some animals mimic the
optic flow of the background, so that the attacker does not appear to move when seen by the target. This is the main focus of work on motion camouflage, and is often treated as synonymous with it. Motion camouflage has been observed in high-speed territorial battles between
dragonflies, where males of the
Australian emperor dragonfly,
Hemianax papuensis were seen to choose their flight paths to appear stationary to their rivals in 6 of 15 encounters. They made use of both real-point and infinity-point strategies. s use infinite-point motion camouflage to close on their prey. The strategy appears to work equally well in insects and in vertebrates. Simulations show that motion camouflage results in a more efficient pursuit path than classical pursuit (i.e. the motion camouflage path is shorter), whether the target flies in a straight line or chooses a chaotic path. Further, where classical pursuit requires the attacker to fly faster than the target, the motion camouflaged attacker can sometimes capture the target despite flying more slowly than it. it is equivalent to CBDR but allowing for the target to manoeuvre erratically. The missile guidance strategy of pure
proportional navigation guidance (PPNG) closely resembles the CATD strategy used by bats. The biologists Andrew Anderson and Peter McOwan have suggested that
anti-aircraft missiles could exploit motion camouflage to reduce their chances of being detected. They tested their ideas on people playing a computerised
war game. The steering laws to achieve motion camouflage have been analysed mathematically. The resulting paths turn out to be extremely efficient, often better than classical pursuit. 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. == Camouflage by motion ==