Re: SAY YES TO "PSEUDO"!

[P3D Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Mon, 3 Feb 1997 03:03:22 +0000
>From: P3D  Dr. George A. Themelis  writes:
>
>"Pseudo" is another fine Greek word that means false, incorrect.  Perhaps
>something in terms of "reverse" might have been a better choice, but I
>have seen a couple of beginners mount their first rolls in reverse and
>I can assure you that this is INCORRECT!!!!  

*****  Yes, incorrect for the intended circumstances. This doesn't make the
depth which is displayed incorrect, merely inside out. What was deep into
the image now projects equally outwards. An image of a desk in reverse is
still the desk, merely the inside aspect of it's outer surface. What is most
unusual is that because that view is usually occupied by the solid material
of the desk, we never think of that aspect of the surface. Yet it exists and
is very real. It is even the identical object shape and dimensions, just
reversed in relationship. 
I find a fascination with roots that have grown in and around rocks. Their
dimples, turns and tortuous twistings are the inverse shape of the rocks
which was present during their growth. Another example of nature's use of
the inverse shape is the lowly egg shell. Our predominant image of an egg is
it's outward manifest shape. We might envision holding it in our hand or
cracking it open on a table (or someone's head). We may examine in passing
the concave curvature of the inside surfaces of the egg. Consider for a
moment the initial experience for a developing chick, it is completely
oriented to the *insideness* of egg shells. Familiarity with any particular
physical phenomenon defines it's usefulness to us. We are more familiar with
the outside nature of a desk, so see the inside representation as very
different. If we were more aware of inside surfaces for some reason, so
called *pseudo* might be our preferred form of stereo image.

Another reason to explore the inverse example of stereo is that what at
first seems strange, seems that way because of our expectation. If by
exploring this inverted relationship we become familiar with it, it becomes
far less confusing. This point of acceptance of the nature of the experience
leads to more easily assimilating other stereo images. When an accidental
reversal presents itself, there isn't a dizzy puzzlement. The web pages that
show both parallel and crossed versions next to each other are quite
interesting in both their expressions.

>......................Reverse-mounting a stereo
>image is not "fully natural" when we are talking about an ordinary scene
>that we are trying to visualize correctly.  It is "un-natural", it is
>incorrect, and the reversed sense of depth is plain false.  

*****  It is only unnatural in that we don't normally observe things as
inside out. It is still a natural thing because nature does lots of inside
vs. outside shape arrangements, some more familiar than others. It is only
incorrect relative to the application and in fact images for crossed viewing
intentionally reverse this relationship for a defined purpose. So I must
conclude that the term *pseudo* just doesn't fit a full understanding of
reality and is somewhat inappropriate in any sense other than the tradition
of it's use. 

BTW what is the greek term for *reverse* or more appropriately *inverse*?
There is likely some special word for it since it should be well known
within mathematical and geometric considerations.

>..................
>As a photographer and "artist" (?) I have done my fair share of
>experimentation and have been exposed to good "pseudos" but I do not
>object to a term that says it as it is, i.e., the sense of depth is
>"false", i.e. it is reversed compared to the one in the real scene.

*******  The truth is that every stereo image pair exhibits both a normal
combination and it's reversed relationship. Correctness is relative to the
viewing method. My objection to the term *pseudo* is precisely because it
does NOT say it like it is. The depth is very *real* so it can't be *false*,
it is merely in it's inverted relational form. If it were false, imitation,
fake depth, it's inverse would also be somehow false and it most certainly
isn't.

Since the word has been used for this purpose from long ago, I don't suppose
any discussion will change that usage. So on with the discussion... :-)

>
>Now, if a real scene never existed, as in a computer-generated wire
>diagram with zero perspective, then both regular or normal and "pseudo"
>or "reversed" views are correct and acceptable, but this is a very
>special case.  That's the natural female-male relationship that Larry
>is talking about.  But if you only introduce linear perspective to the
>wire model of a cube then there is a conflict between stereopsis and
>perspective if you want the cube to remain what it is supposed to be,
>i.e. a cube.

*****  Whoa! This is bogus science.;-) No image is anything more than an
image. Regardless of whether it's origins were from an artists brush or
photos of the flowers in your garden or a wild thought in someones dreams.
Zero perspective results in the definition of flatness, no matter the source
for the image. Even the computer can acurately model perspective
arrangements. Provide any image whether from a photo or generated in a
computer the proper perspectives and you have some form of stereo image. ANY
stereopsis can be viewed in either relationship. If there is zero
perspective change, both variations will appear identically flat.

Any time a stereo image is reversed there is an equal reversal in all it's
stereo related aspects. This is equally true for stereo photos and computer
generated image pairs. Perhaps there is a greater complexity in the photo
image, but the relationships when reversed follow the same laws of physics.
Some have suggested that photos viewed in reverse are not understandable at
all due to the confusion of unfamiliar relationships. The key here is
familiarity. If you make a point of examining a few stereo pairs in reverse,
it begins to make sense and all parts are present and accounted for. They
begin to take on meaning and association which is accurately expressed
relative to a physical reality, though reversed due to the viewing process.

The inverse of a cube is still a cube. It doesn't become something else.
None of it's previously visible parts mysteriously disappear. It is a less
familiar aspect but it's still real in terms of being able to experience it.
Simple images and shapes are far easier to digest in the reversed form with
either cameras or computers as a source. When you say *remain what it is
supposed to be* you only refer to what is considered familiar. The fact that
a flip side exists doesn't nullify either aspect.

So I can accept your argument in favor of the word *hyper* but *pseudo* just
can't be supported by logic.

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


------------------------------