P3D Re: " Orthostereoscopic"; Tautomorphic

[abram klooswyk <abram.klooswyk@xxxxxx>]

Larry Berlin (the non-cyclopean :-)) wrote (P3d 3659, 21 Dec 1999):
>The angles, though primary to the experience are basically
>ignored in the definition of Ortho.

However, the glossary *definition* of the term orthostereoscopy does
not include any distances or angles.
Theoreticians have formulated conditions which, when fulfilled,
would give an orthostereoscopic image. Some even have said that
those conditions are obligatory. Formulating different conditions is
possible without changing the meaning of "orthostereoscopy".

Still the definition does not include conditions, and from a
stereo perception point of view it is unlikely that precise
conditions are important.
(I also wrote on this in P3D 3657, 3658, 20/21 Dec 1999)

W.C. Dalgoutte's 1967 stereo glossary, first published in The
Stereoscopic Society [UK] Bulletin, is considered by many as one
of the best glossaries, it is now being revised by Donald Wratten
and others for use by the International Stereoscopic Union.

Dalgoutte said:
Orthostereoscopic image -  one having 'right-looking solidity',
in which the space-image resembles the original closely, but is
not truly 'tautomorphic' (as in gigantism and lilliputism).

Tautomorphic image - one which has the 'same form and scale and
position' as the original object, where stereomagnification = 1.

In Donald Wratten's new draft the latter is expanded to:
Tautomorphic image   - A stereoscopic image which
presents the original scene to the viewer exactly as it would
have been perceived  in life; ie, with the same apparent
scale, positions of scenic elements, and a stereo
magnification of x 1 for all subject matter in the view.

The term "tautomorphic" seems not to be used very often, its
definition describes what mostly is meant with "orthostereoscopic"
on this list. But by strict definition the terms are different.

Note 1: The origin of the terms goes much longer back than 1967.
Note 2: "Ortho" is used sometimes as abbreviation for
              orthoscopic, which is the opposite of pseudoscopic.

Abram Klooswyk