[MF3D.FORUM:1145] Re: Deviation and Viewers

[Abram Klooswyk <abram.klooswyk@xxxxxx>]

Michael K. Davis  MF3D.FORUM digest 262:
>Which variable(s) actually control the placement of the window? 
>Just deviation, or is there something else as well?

So now we come to the _real_ definition of deviation!  :-).

Recently there was a discussion on the "main list" to
which I wrote (PHOTO-3D  June 29, 2000, see 
http://www.egroups.com/messages/photo-3d): 

"The strict definition of deviation is something like:
 The Deviation of a pair of homologues on a stereo picture is
 the difference between the infinity separation on the stereo
 picture and the separation of that pair of homologues.

 In looser usage, for the infinity separation (which is often
 not measurable) the far point separation can be substituted.

 In the stereo base discussions often the deviation of the
mask
 aperture is used. Its separation is easily measured on the
 mount, and it is mostly known already. Then only the
 separation of infinity homologues or of far points have to be
 measured to compute the mask deviation on the mounted slide
 (or card). This is often the largest deviation of the slide,
 unless something gets "through the window."

What you have called deviation probably was near point
deviation. Mask deviation mostly is equal to it, or slightly 
larger. Bringing the window forward with respect to the 
perceived 3D scene is done in practice by masking, 
but technically it is: increasing mask deviation.

Abram Klooswyk