[ulrikrasmussen]

What about correlation? If you have other information that can tell you who is alone in the bathroom (common area CCTV, log of RFID key usage, etc) and your radar can infer that something very private is taking place there because the person thinks they are alone, then isn't that still a huge breach of privacy?

[krasin]

I really must have phrased my message more clearly. I meant reconstructing images, not identifying who is inside. The latter is quite feasible, and you're correct that extra data helps with that as well.

Just like with browser pinning, we have a variety of signals, which combined together give a very high rate of correct identification.

[ulrikrasmussen]

Got it, I think I read your message as defending the idea more than it was.