P3D Re: " Orthostereoscopic"; Tautomorphic

[Larry Berlin <lberlin@xxxxxxxxx>]

> Date: Thu, 20 Jan 2000 
> From: 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.

****  What is the Interocular distance if not a distance?


> 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".

****  I forget now who said what when this thread started, but someone
wrote a very enlightening message detailing several rather broad
definitions of the term, some of which seemed -loose enough- to express
the concept in ways that allow the variations I feel should be there.
However, in this list, it seems that the most stringent of definitions
is the only one acknowledged. When one mentions Ortho here it seems to
usually mean a very tight set of circumstances. It is variance from this
narrow definition which gives rise to the somewhat nebulous terms Hypo
and Hyper. 


> 
> 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)

****  Ah, it was your message! Thanks I enjoyed those messages very
much.


> 
> 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

****  Well, to me that makes a lot more sense, though I understand
something of why Ortho has come to be used for tautomorphic. It's more
familiar as a word apparently, and it's used in other (non-stereo)
capacities in which it does convey a meaning of precision. Used as
merely the opposite of pseudoscopic is a broad lattitude for
interpretation.

So what does Bruce think now? Does Ortho still need a makeover?
-- 
Larry Berlin

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