Well, not really invisible, but close to it. It has cameras to capture images of the surrounding landscape, which are then projected onto the tank's surface. When you look at the tank, you see what's on the other side.
Of course, it's far from real invisibility. You have to be standing right where the system thinks you should be standing in order for the tank to be completely invisible. But it should, nevertheless, act as very good camouflage, especially when the background is relatively uniform.
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