Optical Camouflage

Mike Siekkinen writes "This optical camouflage project is pretty interesting. It contains three videos demonstrating it in action. Basically they overlay a video projection of what the background behind the object to be camouflaged looks like. So if you were standing in front of a book shelf an image of the portion of the bookshelf you are blocking would be projected on to you. The results are probably better than you would expect."

Comments

Re:holy sh*t

[lommer]

Ya, and it also requires that you have a half-mirror (one of those ones the cops use to watch interrogation rooms) in between you and the viewer. That is fine when you are dealing with a camera, but it isn't practically applicable to most areas that this would be useful in.

Re:Still can't figure out how it works...

[alphaseven]

Answering my own question here (guess I'm the first person to read the pdf).

We used a pinhole as the projector's iris in order to obtain a perfectly focused image. Furthermore, the projected image through the small aperture on the normal surface is too dim to be perceived by human eyes.

However the light coming out from the projector is reflected on the half mirror then on the screen and goes straight back in the eye to form the image, which is about ten or hundred times brighter than the image on the normal surface. Therefore the image only appears on the retroreflective material so that the viewer can observe as if the images projected on the retroreflective material are occluded by the object which exists in front of the screen.

So the image projected is too dim to be seen, but the objects are covered in a special highly reflective material (not just colored lightly like a projector screen).

I guess it might be sort of like a dim flashlight hitting a bicycle reflector at night, you only see the reflector lit up.