Double depth - definition

[T3D john bercovitz <bercov@xxxxxxxxxxx>]

There were a couple of questions as to what double depth" means.  I 
looked in the index of the "The World of 3D" by Jacobus G. Ferwerda 
and sure enough it's there.  So that's your best bet for a good 
explanation.  If anyone doesn't have the book, contact Harry Zur 
Kleinsmiede (101576.2026@xxxxxxxxxxxxxx) off list for the latest in 
price and availability.  If I could only have one book on 3D, this 
would be that book.
 
I'll try a short explanation of my own.  If you have too much depth 
in a scene, you can increase the separation of the chips until the 
nearest object is behind the window.  This works fine (in my 
experience) as long as you don't have your infinity homologues 
significantly more widely separated than the lenses in your viewer.  
(It is entirely possible to increase infinity separation.  The 
lenses of viewers are supposed to be 65 mm apart but the windows of 
the mask are on 62.2 mm centers so you can increase infinity 
separation from the standard of 63.4 mm all the way up to 65 before 
you force divergence of the eyes.)
 
Another way to do the same thing is to leave the infinity homolgues 
at the standard 63.4 mm on center but decrease the mask aperture 
separation, by, say, 1.2 mm.  You can decrease aperture separation 
by doing surgery on the mask or by cropping an equal amount from the 
left side of the left aperture and the right side of the right 
aperture.  This approach is called "double depth".
 
Both of these methods will put the nearest object behind the window 
when there is more depth than allowable under the existing rules 
(62.2 & 63.4) in the scene.  However, in projection, the former 
solution causes divergence and the latter solution lifts the stereo 
window off the screen.
 
Quite possibly I've violated the law of minimum complexity (as 
imparted to me by John Dukes) in my explanation.  If so, hit me up 
for further expansion on the topic or read "The World of 3D".

John B


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