P3D Re: Monitors (was - optics of stereo viewers)

[Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Fri, 2 Jan 1998
>From: "Greg Wageman" writes:
>........
>Larry,
>
>I'm curious.  What kind of computer monitor do you use?
>
>The reason I ask is because, as you probably are aware, the screens of most
>computer monitors are spherical.  There are a few so-called "flat screen"
>monitors, which are in fact not flat, but cylindrical (curved in one direction,
>rather than two).  The reason with this has to do with the physics of making a
>large, glass surface strong enough to withstand 1 atmosphere of pressure over
>the screen surface with a near-vacuum inside without imploding.
>
>Most people who routinely use spherical screens are not aware of the curvature,
>until they have an opportunity to use a "flat" screen, and then when they
switch
>back the "pincushion" distortion becomes very obvious.
>

*****  I use a ViewSonic 17GS which has what is called a flat screen. I also
have a smaller monitor which is an earlier model of ViewSonic and it's NOT a
flat screen. In shopping for my big monitor, I tested many models and styles
of screen.

There are two types of *flat* relative to monitors. One is the physical
shape factor which is the ONLY thing being referred to by manufacturers.
What I measured for, was stereo flatness, a measure of consistent pixel
distribution. I quality checked each screen by freeviewing repeated
wallpaper patterns, which any computer already has available. Some stores
are a little touchy about going into the control panel to arrange for this
process, but most were willing to let me look.

What I found is that MOST monitors, flat or not by terminology, were NOT
flat as stereoscopically measured. Meaning that identical pixel patterns
tend to be closer together in the center of the monitor than they are at the
outside. The pincushion control ONLY messes with the outer area of pixels,
so instead of fixing the central bulge, it just allowed me to twist the
edges of the view, like a top view of a mexican hat in which the wearer is
able to turn the edges up or down. 

Any stereo image viewed on a monitor is affected to some degree by this
pixel placement accuracy. LCS viewing is less affected by this factor than
freeviewed images.

I bought ViewSonic because it provided the best pixel accuracy flatness of
all the monitors I could find at that time. They have some kind of double
process designed into their inner focusing system such that an extra degree
of accuracy exists which I was able to measure with my eyes by freeviewing.

Since then, my computer dealer has found another monitor (similar in stereo
flatness to the ViewSonic), that is a bit cheaper and checks out as flatter
than the standard monitor of most other brands including big names... It's
called *CyberVision*. There may be other brands that have stereo flatness.
If stereo 3D is your interest, it's worth checking this factor and being
particular about it BEFORE spending your money.

Whenever you need to check specific flatness or geometric accuracy of a
stereo image or portion of an image, it's helpful to know exactly how flat
or non-flat your monitor is so you can account for apparent depth
discrepancies. This flatness applies to standard rounded screens equally as
the *flat* ones. Common distortions exist in both, or they can appear
equally flat in stereo.

Larry Berlin

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


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