T3D Re: viewing disparity

[john bercovitz <bercov@xxxxxxxxxxx>]

Gabriel writes:

> For example, if you have a left and right image stereopair not mounted,
> put them side by side and freeview them crosseyed. They will look
> slightly smaller. Now separate the images and continue to freeview
> them. You'll notice the fused image get progessively smaller. 

That reminds me of an instrument I saw in an optometrist's office a long 
time ago.  The optometrist said it was to help people whose eyes tend to 
cross.  There were two transparent Polaroid sheet images, one on top of 
the other and they slid in a track.  There was a light source behind them.  
You could wear Polaroid glasses and then each eye would see only one of 
the images.  I tried it and it was fun to see how cross-eyed and how wall- 
eyed you could go without losing fusion.  The nice thing about this setup 
is that there is no vergence angle which is difficult to produce.

John B


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