Sorry for being somewhat off-topic but I have a stereo-related anecdote. ;)

When setting up stereo cameras in a virtual scene, one should consider which 
eye separation will show off the virtual object or  scene in the best 
possible way.

For example, if you have a height-field of a mountain, you could show it off 
like a small model hovering in front of the screen (this will give great 
depth information to your eyes). This is achieved by using a very large 
stereo separation between the virtual cameras, as if you are a giant looking 
at the mountain.

Alternatively you can make the mountain 1:1 and have it be an enormous 
mountain that extends far into the screen. This gives less depth information 
to your eyes for the far parts (like with a real life mountain) but it gives 
a great sense of immersion, like actually being a small person looking at a 
real mountain. This is of course achieved by using a realistically small 
stereo separation between the virtual cameras.

Now, in animations and simulation, the stereo separation can be dynamically 
changed. The movement in camera positions is so subtle that the eyes don't 
even really notice it. So imagine this:
You are looking at a small model of a mountain hovering just a few feet away 
from your eyes. Then gradually, without the mountain or camera seeming to 
move at all, you're suddenly looking at the exact same image, except that 
you're looking down at a huge mountain underneath you. The mountain didn't 
seem to grow bigger, because it still fills the exact same area of your 
field of view - suddenly it just *is* bigger!

I have tried this in an OpenGL simulation I made together with two others, 
which we had the opportunity to see in a 3D panorama (wearing 3d glasses) 
and it's one of the weirdest visual effects I've seen. It literally takes a 
little while for the eyes to understand what have happened - they're not 
very good at spotting the changing separation as it happens.

Well, just one of the fun things you can try with stereo effects. :)

Rune

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