P3D Re: base sep formulas

[Michael Watters <mwatters@xxxxxxxxxxxxx>]

Paul Talbot asks:

>I was standing at a scenic overlook.  The ground fell away from my
>vantage point so it would not be a problem.  It fell down to a body
>of water, across which stood two volcanoes.  According to the signage,
>the two volcanoes were 52 and 54 miles from my vantage point.  I could
>set my SLR 70-210 zoom such that distant volcanoes filled the frame,
>with no foreground objects in the scene.  What should be the stereo
>base?

Well, thinking only of the first volcano...  That's basically 50 miles away with a 200mm  
lens...   Using the quick and dirty version of the formula, that's 50/200 or 1/4 mile for the  
base seperation.  That'll put a 1mm parallax between the first volcano and infinity.  If you  
wanted that much seperation between the two mountains instead, you'd need the full  
blown version:

B=pS1S2/F(S2-S1)

B=1.2*52*54/210(54-52)
B=3000/420= about 7 miles

See why it's so much nicer just to step back and stick a bush or something in the  
foreground?  :)  :)  :)

mike


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