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From: slag@charm.UUCP (Peter Rosenthal)
Newsgroups: net.movies
Subject: Re: Re: 3d movies: does this make sense? - (nf)
Message-ID: <365@charm.UUCP>
Date: Tue, 29-May-84 12:12:54 EDT
Article-I.D.: charm.365
Posted: Tue May 29 12:12:54 1984
Date-Received: Fri, 1-Jun-84 06:18:06 EDT
References: <852@cbneb.UUCP>
Organization: Physics Research - AT&T Bell Labs MH
Lines: 29


	This discussion needs an appropriate definition of what
we mean when we say 3-D imaging.  Of course a viewer can pick
up depth cues with one eye, by looking at how objects overlap.
And a photographer can change depth illusions by varying
depth of field, lighting, etc.  But I don't consider that
3-D imaging.  Try some experiments with one eye.  Have
a friend hold up some objects squares of different sizes for
example.  See if you can tell how far away they are with
one eye if you don't know their size apriori.  Now try
it with two eyes.  Its a big difference.  There is definitely
something that true binocular vision shows that monocular
vision can't.  For instance,  Its true that by opening
up the aperture will cut the depth of field in an exposure
and this can be exploited to enhance the depth of a picture.
This works because objects at different distances will
be in various degrees of focus.  Thus the objects at
the focus of the picture will be sharp but those things
closer or further won't be.  We interpret the cues of 
focus depth in terms of distance.  But if you want
everything in the scene to be in focus,  you lose this
type of depth.  With binocular 3-D images, or holograms,
you are free to focus on any part of the picture.  The
only focus limitations are those of your eyes.
	If you stop and think about it,  There is no way
that a two-dimensional sensor (the retina) could ever
collect more than a two-dimensional image.