# IR invisible tank



## Metryq (Sep 7, 2011)

*‘Invisibility Cloak’ Makes Tanks Look Like Cows*

No "seismic anomalies" this time, just mooing.


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## Vertigo (Sep 8, 2011)

It's still really only a pseudo "invisibility cloak" as it has no knowledge of the viewing perspective of the observer. So if the observer were viewing at a sharpish angle then the background displayed on the panels may not match the real background as seen from that angle.


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## Metryq (Sep 8, 2011)

I've considered the problems of "dynamic camouflage," which is not the same thing as invisibility. In very few words, Vertigo has nailed what sounds like a simple problem, but is actually very complex. 

The basic idea behind dynamic camouflage is that a person or vehicle is covered with video screen-like material. Micro cameras on the opposite side of the armor pick up the view to be repeated. Problem number one is reproducing the dynamic range (deep blacks to blinding whites) of the world around us. HDR or "high dynamic range" video has existed for a few years, but even the very best systems are not perfect. 

Okay, so let's assume perfect dynamic range.

Problem number two is "horizon." Assume someone covered in DC, like the alien in the movie _Predator_. Let's assume the user is crouched down to best illustrate this problem. Do the cameras on his back feed to the camo on his front, 180 degrees around? If so, the bright sky hitting his back will bloom on his chest. For a video DC system to work, it will need some kind of artificial horizon to roll the view. The problem is even more complex between arm and chest, or between legs—does the system produce video feedback like the art of Nam June Paik, or is it smart enough to feed through its own pickups and repeaters "straight through"?

Problem number three is parallax, and this is the biggie. We have stereoscopic vision, and unless the DC is "glasses free 3D," one eye will be offset from the repeated view. Thus, the user will not be completely "invisible," but create a glass-like refraction in the scenery. Still, there's no reason to believe that even one eye will be aligned properly. As noted by Vertigo, what if the DC armor is not aligned at all with the background, like someone viewing a TV screen from the side?

Limited invisibility (partial spectrum) may be possible one day, but I don't think dynamic camouflage is the way. (One of my favorite gaffes in a James Bond movie was in _Die Another Day_, if I'm remembering the title correctly. Q branch supplied Bond with a DC car. Bond drives up to the bad guy's lair—through snow, no less—and quietly slips out of the car when the guards' backs are turned. Upon returning, _Bond hides behind one of the car's fenders so the guards won't see him..._)

One type of "invisibility" I had never considered until I became a _Ghost in the Shell: Stand Alone Complex_ fan is the hacking of augmented reality systems. That is, everyone in this story has a cyberbrain implant that, among other things, can display data directly in the user's field of view. (Consider the translation service in *Word Lens*.) In the "Laughing Man" story arc, a computer hacker committed a "crime" in broad daylight in the middle of a crowded city plaza, yet no one saw the perpetrator's face because he arranged to hack all their cyberbrains and mask his face with a logo that earned him his nickname. (Actually, this is similar to any number of action movies where someone injects video of an empty room into the feed of a security camera, as in the movie _Entrapment_. The only difference is no one expects their own eyes to be overtaken that way.)

Perhaps invisibility is a wild goose chase. Stage magicians already know how to distract us, and special ops commandos already know how to "turn invisible" and slide through key holes. In other words, whatever the job, there is probably a far less costly way of getting something done than bending light over backwards to make a completely seamless and reliable invisibility screen.


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## Vertigo (Sep 8, 2011)

I tend to agree with you there Metryq, in that this kind of dynamic camouflage seems to me to fundamentally unworkable. About the only way I could see it working would be to mimic the surroundings. So if you are in a jungle you will look like jungle "stuff". This is not invisibility, just much better dynamic camouflage, making it easier to blend into the background. The only other way I could see invisibility being achieved would be some kind of lens effect that "bends" light around you from any direction. Even if there was some sort of (portable) physics that would allow this, it would seem to present a problem of not letting the person inside actually see anything outside!


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