[quote=@Little_ninja]
<Snipped quote by Stale Pizza>

Uh....
Where did you get this info from?
Source please

It would be simpler if it worked on facial recognition, as it does scan the face (which is how it got the face for SAO)
[/quote]

1st Episode of the original Sword Art Online arc. When Kayaba appears, and they get changed back to their normal appearances, Klein guesses that the system knew how they looked like: "Did you remember that when you had to install the game, they told you to 'calibrate' your body by touching it all over?"