P3D Re: Stereo Nomenclature

[Bruce Springsteen <bsspringsteen@xxxxxxxxx>]

Abram Klooswyk wrote:
>An "orthoscopic" image  is a stereoscopic image viewed with its
>planes of depth in proper sequence, as opposed to a pseudoscopic
>image.
>"Orthostereoscopic"  refers to a space image which resembles
>the original scene closely.

In checking Ferwerda, I see that this distinction is made once briefly. 
Haven't yet seen it elsewhere, but my stereo library is not huge, and I
certainly accept that this is standard.  I have to say that orthoscopic
seems rather a broad term to apply to such a narrow meaning as
non-pseudoscopic (as distinct from non-pseudostereoscopic - is it any
wonder we get so confused?!), but it hardly ever is used in this context,
from what I see, and can do little harm.  I will try to stop using it when
I mean orthostereoscopic, in deference to our esteemed stereo-ancestors.  
  
 
>Orthostereoscopic, orthoscopic, cyclopean probably could be
>replaced by better terms, but they have been used by some
>generations in numerous books and articles.
 
>"Stereoscopic" itself is a questionable term, we don't see only
>"solids" in 3D. But should we try to rewrite all terminology?
>Apart from being ridiculous, it would cut us off from
>understanding  the older literature.

Indeed we should be cautious whenever we change an established usage, and
try to have good reason and a clear need.  On the other hand, science
requires a re-evaluation of terms as well as concepts when they prove to
be a barrier to clarity or new understanding.  I have no quarrel with the
term "cyclopean image".  It is quaint and I think not too distracting, not
so much as it is for Larry anyway.  

Speaking of Larry, I get the sense that he doesn't like the notion of
"ortho" much in any sense of the word.  My only objections are that it
includes the "recording" requirement, and that it is often expressed in
terms of secondary necessities like focal length matching and IPD,
confusing the issue.  I don't, however, see a great persecution by
ortho-zealots against those who like to view or present their views in
non-ortho ways (like free-viewing, which Larry promotes).  I don't insist
that all stereo be viewed in an ortho manner, or even expect that is can
be.  I do however expect that people who promote the stereo hobby, myself
included, should take the time to understand the concept, so as not to
spread misinformation, and so they may know what they are seeing when an
image looks different under different viewing conditions.  "If you can't
see it, it isn't there" 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 it is in my
long-term interest to know that they exist and how they act upon me and I
upon them.  And often the things we "can't" see may be seen with study and
practice, enhancing our experience and appreciation, and improving our
practice in unexpected ways.  I think these stereoscopic matters are that
way.  I "see" much more now than I did at the beginning, and am glad for
it.

I will be leaving for holiday visits for the next week, and likely will
not have access to email, so I must appeal to my brilliant P3D friends to
join me in that long-term approach to this topic.  I expect to hear more
criticism of my "ortho-theses nailed to the P3D door", and engage in some
robust discussion on my return, so I hope the topic will not run its
course in my absence!

In the meantime, here is another proposal: 

Recording may be normal, hyper or hypo stereo (depending on base at
"average" or not).

Viewing may be ortho or hetero stereo (depending on the presence of
deformations or not).

So we may have normal orthostereo, normal heterostereo, hyper-orthostereo,
hypo-heterostereo.  Or whatever combination of recording and viewing is
before us. 

Seems orderly and clear to me.  Maybe you feel otherwise? ;-)

Best wishes to all,
Bruce






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