P3D Stereo Window Demonstration

[Project3D@xxxxxxx]

In a message dated 24/02/00 14:52:49 GMT Standard Time, Dave Kesner wrote:

<<  
 > As Gabriel pointed out, the window can be off the screen in
 > projection.
 
 Yes, but this is wrong (as I stated earlier) as you have to mis-align 
 the two chips to achive this. Translated - if you move the window in 
 projection either behind or in front of the screen then there will be 
 excess image that does not have a counterpart or better yet - there 
 will be an ugly strip of usless information on either side.>>

And, Dr Dave, _you_ have missed the point of moving the window off the screen!

If a slide is mounted so that the infinity points will appear at infinity 
when projected, then it follows that the projectionist should separate these 
infinity points on the screen by the eye separation of the viewer. (If there 
is more than one viewer you would use the average - say 2.5 inches...)

Now, because these points have the same separation as the eyes, the lines of 
sight will be parallel, and the object depicted by the points will be 
percieved as at infinity.

BUT (unless your projected image is approximately 4ft high for a Realist type 
camera image...) the window will actually be in front of the screen for 
larger screens...

I don't wish to get into the maths here, but it's clearly detailed in the 
Morgan & Lester "Realist Manual" (amongst other sources...)

The projectionist has absolutely _no_ control over the positioning of the 
scene relative to the window. The best he can do is avoid audience headaches 
by minimising the eye-gymnastics that bad mounting can cause...

Bob Aldridge
Stereoscopic Society Projectionist
 
 
 
 That's all for now,
 
 David W. Kesner
 Boise, Idaho, USA
 drdave@xxxxxxxxxx
  >>