T3D Re: Panum's limit

[Jim Crowell <crowell@xxxxxxxxxxxxxxx>]

At 9:31 AM -0700 4/2/98, john bercovitz wrote:
>Panum's limit is around 10 or 20 minutes of arc per something
>Jim C wrote a few years back.  Beyond that, you get retinal
>rivalry due to parallax.  The 1 in 30 rule (on-film deviation
>shouldn't exceed 1/30th of the focal length) works out to about
>2 degrees.  This is a long way from 20 minutes.  I wonder if 1
>in 30 isn't an upper limit to a sort of "Panum's range" and 20
>minutes is the lower limit.  I'll bet when they tested and got
>the 20 minutes figure, they were using the starkest targets they
>could find.  No diffuse stuff, no stuff that is more typical of
>the average scene, which is bounded by a 2 degree limit.
>
>John B

I think you're right; to paraphrase, Panum's area is probably measured
measured using displays with most of their power up at high spatial
frequencies (i.e. consisting of fine features, no changes in brightness
between widely separated parts of the image); everyday scenes with more
power at low spatial frequencies might be much more tolerant of disparity.
Been a long time since I read any of this stuff though.

-Jim

----------------------
Jim Crowell
Division of Biology
216-76
Caltech
Pasadena, CA
(818) 395-8337
jim@xxxxxxxxxxxxxxx



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