Viewing System of Choice

[P3D Oliver Dean <3d-image@xxxxxxxxxxxxxx>]

Bill Costa wrote:

>  David Hutchison (<DavidH8083@xxxxxxx>) recently posted:
> 
> >    I would vote for the Polaroid version, since the LCD version suffers
> >    from the sync problems inherent to field sequential display systems.
> >    The problem manifests itself with that well-known distortion of rapid
> >    action in which fast-moving lateral action breaks up into a kind of
> >    apparent "watery ripple". I find it very annoying.  Others are less
> >    bothered by it.
> 
>     Interesting.  I have seen the LCD versions of 2 films in NYC ("Into the
>     Deep" and "Across the Sea of Time") and the LCD version of "L5" in
>     Vegas and in neither case did I notice this.  I'll have to watch for it
>     next time.  I would have thought the higher than average frame rate of
>     the IMAX system would solve this particular short-coming with LCD
>     systems.
> 
>     Does anybody remember the frame rate used on an IMAX system and how
>     that compares to a conventional 35MM feature film?

Sorry -- I'm entering this thread late, and have missed what has gone
before, but you mentioned the magic words "IMAX system," and I had to
share with you.

Yes, I also have seen the LCD versions of "L5" (3 times!), "Across the
Sea of Time" (3 times!), "Into the Deep" (5 times!), and "Wings of
Courage" (3 times) at the new 3D IMAX in nearby Irvine, California.  I
can compare these with having seen "Transitions" twice and "The Last
Buffalo" twice in the old IMAX Polaroid glasses system. 

I think I can say from a a position of experience that, for me, the LCD
glasses system showed no sign of the annoying "watery ripple" that shows
up with LCD videos taken with my Toshiba SK3D7 stereocam, and appears,
for all practical purposes, to be as "solid" as 3D IMAX made for the
Polaroid system. The "watery ripple" effect, similar to the effect seen
when a stereo movie is about 1/2 frame out of sync, is most prevalent
with objects that move rapidly in a vertical direction, and vertical
water fountains video'd with the SK3D7 lose all sense of cohesion in the
water droplets.  However, in L5, there is a scene at the beginning in
the "garden" that shows a very close waterfall, only about two or three
feet away, that acts as a transparent "curtain" between you and the
background garden, and there appears to be no problem with it.  Birds
flapping their wings are another kind of shot that is especially
susceptible to this effect, and the bright red lorikeet (the little
girl's pet bird, "Torch") at the beginning of "L5" likewise seems to be
free of such problems.
  
All that being said, what works for me may not work for someone else
with a different physiological "threshold" for this kind of perception. 
But it is clear that the greater the frame rate, the less apparent the
effect.  If my information is correct, the IMAX 3D frame rate for each
eye is a solid 48 frames per sec, which would be considerably better
than the 30 fps for each eye with my flickery Toshiba.

But both IMAX systems seem to have their advantages and disadvantages --
the LCD system's heavy, bulky, complex headset is a minus, but the
"personal" speakers in the headset DO add an intimacy for some audio
effects that is hard to reproduce with auditorium speakers.  The
Polaroid glasses have an annoying tendency to "ghost" unexpectedly,
especially with an unconscious head tilt or with viewing from a sharp
angle from a side seat, although ghosting was minimal with the excellent
quality of the IMAX polarizing materials and screen surface.  The
Polaroid method also requires a metallic surfaced screen (more
brightness fall-off from the side; also, more expensive?), which is not
necessary with the LCD glasses.  Polaroid glasses are passive (no sync
circuits and no LCD's needed), are MUCH lower in cost, and are lighter
in weight -- and on, and on.

On balance, I don't care WHICH IMAX system is used, just so long as it's
in stereo and the quality of the equipment, the script, and the stereo
cinematography are all satisfactory.  For me, both systems are capable
of generating the most exciting stereoscopic experience that the
technology can currently produce  -- wide-view, eye-filling, tack-sharp,
perfectly syncronized, perfectly matched-pair, well-aligned, full-color,
bright, moving stereo images with stunning sound (the shuttle launch in
"L5" is truly awesome) and an uncanny sense of presence unmatched by any
other system.  What more can you ask?  Anything else would be icing on
the cake. 
-- 
Oliver Dean -- 3d-image@xxxxxxxxxxxxxx
Dominguez Hills (near Los Angeles), Calloushernia, USA


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