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From: hutch@shark.UUCP (Stephen Hutchison)
Newsgroups: net.graphics
Subject: Re: Stereo Picture TV
Message-ID: <1458@shark.UUCP>
Date: Tue, 9-Jul-85 17:43:29 EDT
Article-I.D.: shark.1458
Posted: Tue Jul  9 17:43:29 1985
Date-Received: Sat, 13-Jul-85 07:32:07 EDT
References: <8794@ucbvax.ARPA> <5760@utzoo.UUCP>
Reply-To: hutch@shark.UUCP (Stephen Hutchison)
Organization: Tektronix, Wilsonville OR
Lines: 29
Summary: 

In article <5760@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes:
>There is also a persistent technical problem, in that the 3D image one
>gets from orthodox techniques (like polarization) has some tendency to
>produce mild eyestrain.  The difficulty is that it requires viewers to
>vary the convergence of their eyes (which is a function of how near the
>objects appear to be) independently of the focus of the eyes (which is
>a function of how far away the light-emitting screen is).  Most people
>are not used to this, and I am told that it gets uncomfortable after a
>while.  (Either I don't have a problem with it, or I've never watched
>3D material for long enough to run into trouble.)
>-- 
>				Henry Spencer @ U of Toronto Zoology
>				{allegra,ihnp4,linus,decvax}!utzoo!henry

Separating convergence from focus as a long-term thing is *VERY BAD*.
I have mild systemic damage to my optic chiasm (which organizes much
of the binocular information from the eyes) because I have accidentally
done this (a result of adult ambliopia).  What you get is the inability
to correctly track objects moving toward you quickly, and difficulty
determining exactly how far away things really are.  The real result of
this is a drastic reduction in my response to depth-cued stimuli; it
takes longer to figure out what's happening, ergo I have up to a 3-second
(measured) lag in response over some other folks.

Convergence and focus are interdependent systems, and it would be very very
bad to train them to operate independently.  Unfortunately this is what
would happen if people watched a lot of 3-d that works that way.

Hutch