Stereopsis (what is used by current stereoscopic imaging) and eye convergence requires 2 eyes to work. Deph perception by using eye focus requires only one eye. First 2 methods work mainly at close range (i.e. when you need something to grab, throw something at distant target or catch something thrown at you). Eye focus works at bigger range too, but that range isn't marvelous too and precision diminishes as range increases. Also, even without all that, brain extract lots of depth information from image alone: lightning, shadows, perspective and so on.
We don't loose depth perception with one eye closed, but we loose precision. If you don't have eye problems significant for stereopsis, try catching a ball with one eye closed. Compare it with catching a ball with both eyes open. I think, you will see a difference.
P.S.: by the way, if you use only one eye and move your head to sides, brain will get depth the same way as it gets from stereopsis: it will relate how much you moved the head with how much viewing angle has changed. Works with real world, but of course it does not work with movies. In games you can get this with TrackIR (it really helps while landing a helicopter).
Last edited by ZaltysZ; 07-03-2011 at 05:44 PM.
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