RE: 3D SPEX (and LCS in general)

[P3D Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Tue, 26 Aug 1997
>From: P3D Greg Marshall  writes:
>
>>John Urbanic wrote:
>.....................
>>NO, NO, NO!  You can look at my companies "3D Theory" section on our Web
>>pages (www.neotek.com), but basically, as Greg noted, you can get just about
>>any monitor to go to 120Hz if you keep the total bandwidth (i.e. resolution)
>>the same. ...............................
>>The way we do that is to include hardware which "synch-doubles" or adds an
>>extra vertical refresh signal to the video cards signal.  This allows the
>>monitor to refresh at twice the old rate without changing the bandwidth, or
>>total resolution of the signal as delivered from the video card.
><snip>
>
>Excuse me, I should have known John would jump on this opportunity to
>extol the virtues of "sync-doubling".  But I'll repeat what I said
>before:  Sync
>doubling is no magical solution - you can describe it a few different
>ways but
>the bottom line is exactly what you said:  ...you keep the total
>bandwidth
>the same.  You don't want it the same - you want it to double (same b/w
>for each eye).  In other words, sync-doubling gives you only half the
>vertical
>resolution. Now this is fine and very useful for some applications, but
>it's no 
>break-through technology.

******  Not only does synch doubling NOT provide higher resolution images,
it uses images with half the vertical height. That's decidedly an unwanted
side effect. Technology should be bent to the needs of the humans using it,
not the other way around. Half height images are not natural or easy to look
at or desirable as a method of stereo image work in addition to the loss of
total resolution. Besides, any good computer needs hardware acceleration for
handling todays' graphic intensive environment. Increasing it's power to
handle stereo requirements provides a much truer improvement to stereo
viewing that is extremely cost effective. And the cost is very comparable
even though a lot more is going on electronically in an accelerator board
than in a sync doubler.

I'll stick with normal stereo images and the increased power and better
resolution with an accelerator board. It's the best direction for further
stereoscopic development in computers.

>................. John Urbanic wrote:
>>OR, and this is a big OR, reprocessing the image to mute the problem
>>chromal boundries.  Actually, it is a little more complex than that as the
>>real problem isn't the absolute phospher persistance, but the imbalance in
>>persistance between phosphers.  By doing some image processing to mute
>>this appropriatly (say a high parallax, vertical edge with a large contrast
>>change on the worst chroma), this problem can be eliminated in all but
>>pathological cases
>
******  While this might work in some cases, it wouldn't work in all cases
and represents FAR more work than is necessary. Here again it's a better
approach to improve both monitor screens and the operation of LCS glasses.

.................
>
>Good point, I'd forgotten about DMM.  This is important because this
>technology will probably replace commercial film projectors.  

******  All I've read about this method is what's been discussed here in
P3D. I didn't see anything in what was described that could possibly be used
for commercial film projecting. How is that possible? Wouldn't they melt
down in the intense light and heat?

>However,
>considerable advancement and cost reduction is needed before it can
>be used for "personal" displays.  These devices already use an enormous
>amount of bandwidth to modulate intensity via time division - doubling
>that to provide stereo would undoubtedly cause some TI engineers to
>pull their hair out in frustration!

*****  They should be starting with the spec for stereo image work as the
basis of development. Then not only would it be robust enough for stereo, it
would have no problem with regular applications either. Doubling a process
shouldn't be too difficult if you know that you want it. Just design for it
from the beginning. Too many current difficulties (and associated
re-engineering costs) in computers for both stereo applications and other
new developments, are from precisely this same kind of deliberate
(information is there but ignored) lack of vision. Having run into problems
with past mistakes should provide a lesson to plan ahead in future
developments, or face getting bettered by the competition.

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


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