Scientists in Germany have demonstrated a startling new form of surveillance: identifying people using nothing more than ordinary WiFi signals. By analyzing how radio waves bounce around a room, researchers can effectively “see” and recognize individuals — even if they are not carrying a device and even if their phone is turned off.
From what I’ve just read, the tech doesn’t seem ready to identify people yet. It can supposedly detect hand gestures, but facial recognition I seriously doubt. But that’s probably just a matter of improving the tech. See this article for more info.
From OPs linked article…
that’s a trivial problem to solve. combine this with a camera for facial recognition in a public space. then you’ve got wifi signature combined with the photo/video for facial recognition. then presumably you can use the WiFi signature anywhere else, even without the camera and be able to identify people.