ted@usceast.UUCP (Ted Nolan) (05/20/84)
<No! Don't touch that lever>
You may have heard that two professors here at the U of SC developed
a 3d television system last year. I don't know what has happened to
it since, but that's not relevant to what I'm about to ask.
The most impressive thing about the system (I have seen it briefly)
is that it takes no special glasses, and the effect can be observed
even with one eye closed! The process is secret, but I have thought
about it a little and wondered if this makes sense:
The effect can be seen one eyed because information from both
perspectives is present on the screen in alternating frames,
thus with persistence of vision, the brain can reconstruct depth
without input from the other eye.
This is such a simple idea that I suspect it must have been thought of
before. Does anyone know if it has been tried with movies? It seems
that it would be easy to implement : just have a camera with two lenses
and have them alternate in exposing frames. The final product would
need no special equipment to project nor any headache inducing glasses to
view.
How about if folks? Would this work? Has it been done, or is the idea all wet?
Ted Nolan ..usceast!ted
--
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Ted Nolan usceast!ted
6536 Brookside Circle
Columbia, SC 29206 (feather the rast!)
--------------------------------------------------------------------------------bbanerje@sjuvax.UUCP (B. Banerjee) (05/23/84)
>> >> The effect can be seen one eyed because information from both >> perspectives is present on the screen in alternating frames, >> thus with persistence of vision, the brain can reconstruct depth >> without input from the other eye. >> >> This is such a simple idea that I suspect it must have been thought of >> before. Does anyone know if it has been tried with movies? It seems >> that it would be easy to implement : just have a camera with two lenses >> and have them alternate in exposing frames. The final product would >> need no special equipment to project nor any headache inducing glasses to >> view. >> >> How about if folks? Would this work? Has it been done, or is the idea all wet I saw a brief TV demo of this when it was first announced. The personal impressions were that - a) Flickered far too much. b) The 3-D effect was minimal. As this was based on a 30 sec. clip (showing a cat climbing through the window), I'm open to being shown otherwise. Regards -- Binayak Banerjee {allegra | astrovax | bpa | burdvax}!sjuvax!bbanerje P.S. Send Flames, I love mail.
slag@charm.UUCP (Peter Rosenthal) (05/23/84)
bugbuster
Humans do not see in three D with only one eye. If you
close one eye, even real life loses its three dimensional order.
The human brain translates the combined images from the two
eyes into 3-d information. I've seen systems that alternate
right and left eye images to separate the information, but
some sort of shutter device is still required to keep the
right eye from seeing the left image and the left eye from
seeing the right. Although systems have been made that
do this, and they are not prohibitively expensive, There
is an additional problem: The viewing distance and angle
are very limited; The scene must be viewed from one
position.
Holograms solve this problem. A hologram has a
different image for each viewpoint. This automatically
separates right and left eye viewpoints, and gives
you valid images in true perspective no matter what
your viewing angle. A recent national geographic
has an article on holograms that is very informative. It
even has an actual hologram on the cover.
I don't know if the technology is advanced enough to
develop moving full length holographic pictures.fish@ihu1g.UUCP (Bob Fishell) (05/24/84)
(oo)
The May issue of "Radio-Electronics" describes several 3-D tv
and movie systems. The best of them uses special glasses that are
shuttered electronically in synchronism with the fields of the
picture. The frame rate has to be stepped up to avoid flicker,
but the effect is true stereo vision without color distortion
or orientation problems. It works by showing alternating left
and right frames of a stereo image and shuttering the glasses
accordingly, so each eye sees only its correct image.
The problem is that it's not compatible with existing video
standards, so it probably won't hit the consumer market.
The system could work in a theatre if they could make the glasses
wireless and light enough for comfort, but they'd have to do
something about the 24-frame/s framing rate of the standard projector.
--
Bob Fishell
ihnp4!ihu1g!fishadm@cbneb.UUCP (05/25/84)
#R:charm:-36100:cbnap:19600004:000:876 cbnap!tjl May 24 15:55:00 1984 > Humans do not see in three D with only one eye. If you > close one eye, even real life loses its three dimensional order. This statement is of course quite wrong. It implies that a one-eyed person could do no more than stumble around a room. There are lots of visual clues to depth other than steroscopic vision. These include limited depth of field, natural superimposition of objects, lighting to show form/curvature, lighting to show clustering of objects (all lit by one source), shared movement by groups of objects while observer is moving (close things seem to move more - try looking out a side window on a car). In many situations, these clues are more useful than stereoscopic vision. Good photographers and film makers know how to exploit these clues to make images with very stiking sense of depth.
slag@charm.UUCP (Peter Rosenthal) (05/29/84)
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.
fitz@utastro.UUCP (Mike Fitzpatrick) (06/08/84)
You're right, closing one eye doesn't completely eliminate the 3-d
effect. However, you're explanation is completely wrong. Light
travels at basically the same speed through the atmosphere and the
eye isn't sensitive enough to detect the time change in light arriving
from objects at different distances. The eye only responds to changes
longer than 1/30th sec (or something like that).
--
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Mike Fitzpatrick
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