Re: Cardboard cutouts and backdrops...

[P3D Gregory J. Wageman <gjw@xxxxxxxxxx>]

Dr. T. commented:

>Recently I had the chance to show stereo slides to a few novices...
>They all enjoyed the pictures but two comments got me thinking:

>- They found the background to look like a backdrop.
>- They commented on how the human figures look like cardboard cutouts.

>Also, there has been a discussion about people objecting to
>frozen action.  Or comments on how people look like wax figures.
>I believe that these comments come from novices who are 
>impressed by the realism of the medium... These impressions go
>away with time too as we get used to stereo images.

There are a number of reasons the background could look like a drop;
this isn't unique to stereo.  I have a videotape I made at Shasta
Dam in Northern California with Lake Shasta and Mt. Shasta in the
distance (the "Three Shastas").  The background scene looks very
reminiscent of the old "Paramount" logo.  Atmospheric scattering
had washed out all the colors, a phenomenon frequently recreated
by matte artists.  In stereo, of course, the lack of any significant
binocular disparity at extreme distances only serves to reinforce
this effect.

I can assure you, however, the the effect is *very* different when
the background really *is* a drop, as is the case in some lifesize
museum dioramas I have photographed in stereo.  I attribute that to
the fact that the plane of convergence of a drop is NOT at "infinity"
as the background would be in reality.  Again, this is an issue of
familiarity with the medium.

John R. responded:

>I enthusiastically agree - I think the ability to view and enjoy stereo
>increases with practice. (That, and the ability to decouple visual cues
>and concentrate on the ones the photographer is making use of.)

John, could you elaborate?  I don't know what cues it is we're supposed
to be decoupling.

Mike K. added:

>The "problem" was the novelty of realism in conjunction with
>frozen-ness.  Indeed, with experience, the novelty wears off
>and the "problem" goes away.  The technical "weirdness" is
>still there (meaning the un-naturalness of the visual situation)
>but it isn't a problem.  Well, it never was a problem, it
>just was something mildly startling.  Maybe even something "good". 

Personally, I see a huge difference between "cardboard cutout" and "wax
figures".  The former suggests to me a lack of perceived depth in the
person, while the latter suggests the "frozen-ness" Mike talks about.
I agree with George and Mike that the novelty of seeing real people
captured while in motion with such depth and realism will seem somehow
"unnatural" to the novice, and that familiarity with the medium banishes
this perception.

I have observed some other phenomena that are unique to stereography.
I have some stereos of koi in a pond taken with flash.  The sharply-
frozen ripples on the surface of the water make it look like the fish
are encased in lucite!  This impression has *not* been banished with
time.

Also, when the stereo camera catches things like lights or reflections
in curved surfaces such that they are obscured in one eye and not the
other, or in a different place in one eye vs. the other, strange
binocular rivalries and disparities often result, producing a
decidedly "unnatural" image.  Of course what is unnatural is the
fact that the disparity is perfectly frozen in time, whereas in
life a slight motion of the head or even of the eyes would dispel
the illusion.  In the stereo viewer, however, that sun-glint in
the polished chrome bumper of the car appears to float in space in
front of it.

The "cardboard cutout" effect I think has a different cause entirely
(assuming of course that it isn't simply a failure to explain one's
self with sufficient clarity), and that is the lack of adequate
resolution to provide stereopsis *within* the figure, in addition to
that between the figure and the foreground/background.

>P.S. - I still see cardboard effects though.  Especially with
>       most (but not all) lenticular images I've seen.

Lenticulars frequently exhibit it, but I've seen it in conventional
print photographic stereopairs.  In the former case, I again attribute
it to lack of resolution, in this case of the lenticular screen, although
I think the reduced stereobase of most lenticular cameras plays some
role also (the scene is somewhat hypo-stereo, reducing the disparity of
minor depth cues within an object).

The one case I saw using a View-Magic over/under viewer I
cannot explain, as the images and the viewer provided a good deal of
resolution; yet there was a decidedly cardboard (planar) look to the
entire scene.  Since I don't know with what equipment nor what stereo-
base the images were taken with, I can't draw any conclusions from
that example.  When I mentioned it to Susan, she did not see the effect,
indicating if nothing else that there is some subjectivity to the
effect.

	-Greg W.



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