Sorry joeorc, but I don't understand a thing you said.
The PS eye uses a 2D field of vision, and based on the sizes of the heads of the move controllers it judges the depth.
Natal uses two cameras similar to our eyes only a small distance apart, using the angle to judge the distance as we do. I'm not sure what you mean by this "to see the other side facing" Both have a limited fov, and in their own way a limited sense of depth perception.








