T3D Re: Stereo base equation is too complicated

[bercov@xxxxxxxxxxx (John Bercovitz)]

> I need simplification right now, not more esoterica to wade through.

I'm wounded!  (Sniff)

Probably the 1 in 30 rule is your best bet.  Those beautiful (what 
you would call arcane) formulae devolve to the 1 in 30 rule if in-
finity is in the view.

Another approach is to get a book with charts in it.  I think the 
book I have in mind is by Fritz?  Waack.  I have heard the Polaroid
slide rule does the same thing but I have been remiss and have not
verified this.

Whether chart, slide rule, or formula of ineffable beauty, the object 
is to hold the total parallax down to a tolerable level.  That level 
is 1/30th of the effective distance from your eyes to the images you 
are viewing.  This 1 in 30 is only an average.  Depending on the type
of scene, you can actually have much more parallax on occassion.

This 1 in 30 rule is independent of focal length of the camera.

You also ask about changing stereo base.  This is very simple to think
about.  If you halve the stereo base (compared to your normal viewing
base, your interpupillary distance) then you double the size of the
reconstructed 3D image.  If you make the stereo base ten times normal,
say 650 mm, then the reconstructed 3D image will appear 1/10th normal 
size.  

John B

PS: If you have Excel, you can download one of the spreadsheets that
do the calculations for you.  However, the number of inputs on one of
those babies is daunting to the newcomer, I'm sure.  Tom Deering has
a neat setup to do this calculation on his website but I don't remember
what its constraints/limitations are.


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