P3D Re: Quantifying Stretch

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

My un-orthodox view on this:

>So I would be inclined to say the stretch is 1.58 or 58% rather than 
>1.26 or 26%. I beleive this squaring is what makes stretch so noticable.

Who says stretch is noticeable in a red button viewer?  Only under
controlled conditions and comparison with other viewers people could
even recognize the presence of stretch.

What we call "stretch" is a visual phenomenon and it is rather
subjective and not easily quantified.  I used to see stretch from
my 5" TDC projectionist seat (equivalent to 125 mm viewer!!!),
now I don't.

Here is a simple test anyone can do:  Look at an anaglyph from 
distance A.  Then view it from distance 2A.  Can you tell with any
certainty that depth has doubled or quadrupled?  Some people don't
even see the difference!

If a numerical value is used to quantify this, I'd rather see it
defined as "% increase of longitudinal magnification" or something like 
that.  It is derived from geometrical figures, not from any attempt
to quantify what people really see.

Back to work!

George Themelis


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