Ask Dr. T, part II - Realism & Anaglyph

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Some time back we had a discussion on the realism of stereo photography.
My statement that slides viewed in a good viewer are more realistic
than other stereo formats, was challenged by Dan Shelley.  Dan was kind
enough to send one of his anaglyph images that he considers an example
of realistic stereo photography.  I received the image from Joel Alpers
who got to review it first and had the benefit of reading his (unposted)
comments.

The anaglyph is 8.5x11 inches and shows a nature (scenic) view with a
road (pathway) surrounted by large rocks and trees.

I moved around the house trying to find the optimum lighting conditions
for viewing this image. In the process I realized that good light is
important for viewing anaglyphs and I found an overhead long fluorescent 
light to be the best.

I think I viewed this image under the best possible conditions.  Yes, it 
is stereo.  Yes, I can see depth.  BUT, is that enough to say it is
"realistic"?  Not in my opinion.  There is no way on earth I can convince
myself that I am looking at a real scene.  That's because I am looking
at essentially a black and white image (with anaglyph retinal rivalry)
that is within the limits of a piece of paper in front of me.

In contrast, when I look at a grainless & sharp color slide through a 
good viewer, I can fool myself that I am looking at a real scene through 
a real window.  I am so immersed into the scene that it almost becomes
an illusion.

If someone tells me that this anaglyph is as realistic as a stereo slide, 
I will have to question if they see what my eyes see, especially when 
using the viewer to view the slide.  (I have noticed, for example, that 
people with glasses are less impressed by the realism of slides than 
people without glasses.)

I am not saying that anaglyph is not a valid or it is an inferior stereo
format.  In many cases it is the most practical format to use.  And
Dan's anaglyph is certainly a good piece of work.  But, in my mind,
the anaglyph presentation is inferior to stereo slide presentation,
provided that a choice exists.

I mentioned some difficulty in finding the proper lighting conditions to
view the anaglyph. Another problem is finding the proper combination of
colors and glasses.  The anaglyph glasses that Dan supplied showed 
considerable ghosting (this is very similar to ghosting seen in projection
of slides through weak polarizers).  Joel put another pair of glasses in
the package and this pair eliminated the ghosting.

The anaglyph is returned back to Dan with many thanks for sharing his 
work with us.

Regards -- George Themelis


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