Seeing Around Corners With Dual Photography

An anonymous reader writes "This project (which is part of this year's SIGGRAPH) has absolutely blown my mind. Basically they photograph an object with the photosensor at one point, and the light projector at another, and use the Helmholtz reciprocity algorithm to virtually switch the locations of the camera and projector, showing exactly what the light source "sees"! If that doesn't make sense to you, check out the research page and make sure to watch the 60MB video at the bottom. The playing card trick will leave you speechless!"

Comments

Re:Why don't they just move the camera?

[famebait]

Which gets me wondering: say you can see in someone's window, but the view is not very interesting: you only see a section of wall; everything else in the room is out of view. But: there is a CRT TV on in that room, and you can see its reflected light on the wall.

How much information can you gather from that reflected light?

You could of course recinstruct the image on the CRT, but that's not very interesting.
The TV does not scan a focused image on its surroundings like the projector does, so you couldn't get a TVs-eye view of the room witht eh same technique.

OTOH, it is clear that from sampling even just a single point on the wall, you could get a silhouette of anything occlusion over the screen seen from that point. At least provided you had a pure white image on the CRT, OR knew what image was on and could calibrate for it.

How far could you get with all the information escaping the window in your direction?