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Camouflage in Motion
Adrian writes "Remember Jurassic Park, where Goldbloom stood really still and the T-Rex couldn't see him? Well, there might be a better way. Scientists have found that dragonflies can dissappear by keeping their image on your retina in the same place, even if you move. How they manage it still has them puzzled... ;)"
I've never seen a puzzled dragonfly. Oh. The scientists.
I'd assume that the dragonfly merely tries to keep the thing it's hiding from in the same position on *its* retina. It'd be a fairly simple feedback mechanism, if you did it with analogue electronics.
-Yarn - Rio Karma: Excellent
King Charles 'beheaded' guests who bored or annoyed him by viewing them at such an angle that his blindspot was over their head. Try it for yourself
Well duh. Didn't they ever catch flies when they were young? The way to do it is to take two fingers and follow the fly with them, maintaining the distance between your hand and the fly. after a while the fly will think your fingers are part of the background and will easily let you catch it.
Since there aren't any deatils.
1. What is are the distances involved?
2. Best guess, they're using a single lens camera. I believe dragonflies eat flies. If this is so and the fact that flies have compound eyes, does this test really hold true for their natural prey or just for 'human-style' eyes?
3. I'm not 100% sure myself that dragonflies have compound eyes, but if they do then I would expect that their eyes are accurate enough to see the retina of it's prey (or whatever) and keep itself in the same position relative to those movments.
BTW these are just the quick thoughts of an amateur scientist with 20 years of software trouble-shooting expereience. The points I've made seem logical to me but I've come to the conclusion that logic really doesn't work that well in the waking world.
The GEEK shall inherit the earth...
Dragonflies maybe have near 360 degree vision, considering their large bulbous compound eyes, which might account for the rear-view capabilities?
In any case, the real question is how we as humans intend to take advantage of this knowledge when dealing with similarly equipped, ie steroscopic vision, opponents. It's not as if we can actually move that fast, at least not at close range. Maybe that's it, maybe it's something we could use for our stealth program.... nah nobody uses 'video' for aircraft detection. So what? Project a hologram into your opponents eyes with a laser that makes it seem like you are always in one place? Still I don't see how this is useful. Maybe I'm missing something, maybe it's not 'us' that will be hiding, maybe nano-dust-speck-spy-devices will use this to stay out of sight? hmmm... that at least seems plausible.
Well, here's to applications of esoteric knowledge! *raises glass of champaigne*
A fool throws a stone into a well and a thousand sages can not remove it.
I've seen something like this before. Once I was outside cleaning up after a party. I went to pick up a vase of flowers and I noticed a few tiny fruit flies(?) that were hovering near the flowers. The funny thing was that when I picked up the flowers, these flies would maintain the exact same relative position to the flowers. Even if I rotated the vase around its axis.
It was like taking the flies for a walk on an imaginary but invisible leash.
I guess that the flies had an instinct that to remain still, they must reduce the error in *their* retina between the current background image and the stored background image. I am guessing that dragonflies have evolved to do the same thing but with a greater degree of freedom. i.e. a chosen target rather than the whole background.