If you do not know what the fovea centralis is, please look it up first.

http://en.wikipedia.org/wiki/Fovea_centralis

Now:

The fovea is off center by 4 to 8 degrees (varies from one individual to another, just like noses) towards the temple, away from the central optic axis. (The optic axis is a straight line through the middle of the lens.)

This means when we look at something, the eye is not pointed at that thing, but is in fact pointing away from it by 4 to 8 degrees, towards the outside. Looking at something at infinity, the eyes should diverge 4 to 8 degrees from where the head is pointing.

Assuming a 5 degree deviation (which I use with the BBEye), and assuming a typical separation between eyes of 3 inches, we can calculate the distance at which the eyes should be parallel if looking at some object.

1.5 / tan(5 degrees) = 17.14 inches

So - real people looking at something 17 inches from there eyes have their eyes exactly parallel. Only within 17 inches are the eyes "crossed".

 

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)