P3D Re: Vertical Mounting Standards and Projection

[bercov@xxxxxxxxxxx (John Bercovitz)]

Mike K. writes:

> ...the ortho spot moves back as the projected image gets bigger (recall, 
> for nominal realist format cameras and images, the ortho spot distance 
> is roughly equivalent to 1.5 times the height of the projected image).
> 
> Ortho spot is where the eye's angle of view is the same as the camera's 
> angle of view when the image was taken.  So the ortho distance moves with 
> image size.
> 
> Hope I got that right.  :-)

Indeed you did, all of it.

> P.S. - Of course, one can sit WAYYYYYY back and reduce misalignment 
> problems, but see a basketball turned into a football.  :-)

Not everyone will see a basketball turned into a football.  Those with
poorer stereo vision won't be able to see it.  Like stereo blind people,
these people utilize the thinnest of hints to call up an internal solid
model and cannot use use the full capacity of stereo, so they will not 
know if an object is distorted on screen, or in real life.  Actually,
"poorer stereo vision" is not a good choice of words.  One could argue
that their stereo vision is better because they can get by with fewer 
clues.  Of course one might then fairly say that they are less perceptive.

> P.P.S. - Doesn't this argue in favor of using long lenses on stereo  
> cameras?  That way one can sit WAYYYYYY back and both reduce the effect  
> of misalignment errors AND  be sitting in the ortho spot as well (I'm 
> soon to try this btw)?  'Course you can't see the screen anymore, but 
> hey, what little you see looks perfect.  :-)

Well, you don't have to go _that_, far.  Ferwerda (who was obviously
very perceptive) argued for medium (~70 mm) length lenses on the stereo 
camera rather than the short ones currently found on everything except 
the RBT, where you have an option.  This makes the stereo reconstruction 
correct about in the middle of the usual size audience sitting the usual 
distance from the screen.

John B

8-)  8-)  8-)  8-)  


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