P3D Stereo Nomenclature and some Glossary History 3/3

[abram klooswyk <abram.klooswyk@xxxxxx>]

>From Dalgoutte's 1967 glossary (The Stereoscopic Society Bulletin):

orthoscopic - "seen right-side out", when planes in the stereo
[image] are seen in correct sequence, as opposed to 'pseudoscopic'.

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 a 1977 revision Dalgoutte also added:
orthomophic - In German usage, 'correct for form and scale, but
not for position'; this is an impossible correlation. See
*orthostereoscopic and *tautomorphic.
------
>From the German DIN 19040 Blatt 8 of Mai 1974:
Tautomorph - Gestalt- grössen- und lagenrichtig; vorlagengetrau.

Orthomorph - Gestalt- und grössenrichtig, jedoch lagenversetzt.
------
So the latter definition was criticised by Dalgoutte, and in his
three-language glossary Waack (1986) dropped the "lagenversetzt",
in the English version
"Orthomorph" became: "Correct in form and size".
"Tautomorphic": correct in form, size and position; a faithful
copy.
------
Now Don Wratten is working on a glossary which will be presented
to the ISU.
---------
When George Themelis wrote (P3D digest 3573, 31 Oct 1999):
>Stereo photographers have readily identified this condition:
>B = Bv & F = Fv
>as ORTHOscopic STEREO.
(meaning orthostereoscopic) , I followed his game and wrote
(P3d 3607, 20 Nov 1999):
>the two conditions B = Bv and F = Fv are *necessary*
>but not *sufficient* conditions for Orthostereoscopy.

I must admit that I jumped over the terminology issue just for
the fun of using the expression " *necessary* but not
*sufficient* ", which has a mathematical flavor.

But now that Bruce Springsteen is working on the Philosophy
of Stereoscopy I must be more serious.
More precise would be: when the (specified) necessary conditions
are fulfilled, orthostereoscopy will result.
However, the *definition* of orthostereoscopy does not include
those conditions. The definition is the general philosophical
statement, and leaves open what conditions eventually are
necessary. In practise, the "telestereoscopic close-up" also
comes close to orthostereoscopy, although it violates all
theoretical geometrical conditions.
And then what is this all about? Stereo is for viewing.

Bruce Springsteen (P3d 3648, 15 Dec 1999):
.(...) How is the viewmaker to know what the interpupillary of
>some hypothetical observer will be?
>(...) if an "average" recording value is selected (6.5 cm? 6.2
>cm?...).  But that's a fuzzy ex post facto practicality, not the
>stuff of fundamental principle, and only points up the vagueness
>of this basic stereo rule.

But in the facts on human perception vagueness, fuzziness and
averaging *is* the basic rule.

In biological research in general, and also in vision research,
the results are always in a range, often with a Gaussian
distribution. Not only interpupillaries are in a range, also
perceptions, also all kinds of perceptions in stereoviewing.

All these geometrical stereo theories are good for getting some
general guidelines, in fact they are just for education, not
to be taken too seriously for any practical purpose.
All viewing of stereopictures is about illusions, only
existing in the brain of the viewing person. Any precise
geometrical prediction is futile (don't resist).

Bruce:
>"If you can't see it, it isn't there" [McKay] is true in a casual
>everyday sense, but in another sense it is a ridiculous remark -
>I can't see many things that are there:
>radiation, wind, most of the members of this list.

But in stereoSCOPY actual, perceptive *seeing* is the only
important thing. Sure, when you would measure psychophysically
what people see, you might find that they see more than they
admit, but this *also* is irrelevant in practice.

For stereoSCOPY the McKay quote is true in a basic,
*phenomenological* (this term should please philosophical
minds :-)) sense.
Stereoscopy is about subjective effects, not about theoretically
present entities (like members of the list :-)).

(This was part 3 of 3)

Abram Klooswyk