P3D Computer Displays (used to be optics of stereo viewers)

[GBMars <GBMars@xxxxxxx>]

In response to my post:
>>I wonder if it is really a problem that LCDs are generally small?  I mean,
>>people
>>buy large monitors to get higher resolution, but that doesn't apply (much)
to
>>LCDs.  If you could have 1280 x 960 (or 1024) pixels in a 12 inch display
>>what's
>>the problem?  I know - those of us over 40 can't focus close enough to see
>>pixels that tiny!

Larry Berlin wrote:
>The problem with a 12" screen is that there isn't enough room on it to
>arrange and use many of the windows and panels common to lots of programs.
>In using a 17" monitor, I've sized the fonts to an optimum visible size,
>which would need to be the same relative size on any screen to be equally
>visible. The 17" screen isn't big enough for what I do, so I know a 12" is
>WAY TOO SMALL to consider. If LCD technology can provide smaller pixels than
>CRTs, then I want a resolution correspondingly higher for whatever actual
>area I want relative to size. I'd love 4000 by 2000 pixels for example, on a
>21" or bigger surface. No more hassle with jagged edges in diagonals that
>are far more visible than the current pixel sizes, though intimately
>connected as cause and effect.

My point is that size of a display is irrelevent if you can place the display
at the correct distance to form the same size image on the retina.  There
are practical reasons we can't: (1) If it's too close we can't focus on it
comfortably, and (2) most of us don't have enough room for a large,
distant display.  "Room" can only be measured in pixels - it doesn't
matter what size they are.  A larger font will use up more of the available
pixels (leaving less room for others), but if you could use a small screen
at a suitably close distance you wouldn't need to increase the font size.

>>Anyway, what this all means to stereo is mixed:  Larry Berlin might be happy
>>that LCDs have virtually zero geometric distortion (unlike CRTs), 

>*****  In some ways I don't care what the surface of the CRT is like as long
>as it's stereo operation is flat. But I would like a flat device instead of
>the big heavy glass thing with a vacuum inside, and for now that looks like
>LCD in some fashion.

Geometric distortion (specifically, non-linearity of the horizontal sweep) is
what causes the lack of what you call "flat stereo operation".  The spacing
between horizontally adjacent pixels is not the same on one side of the
screen versus the other.  When freeviewing side-by-side images this will
create horizontal disparities which are perceived as depth distortions.
This will NOT affect images viewed in anaglyph or with LCS glasses since
the same distortion applies equally to both L and R views.  The distortion
is then just like it is in 2D.  CRTs also have other kinds of distortion which
make them less than ideal for critical viewing of photographs.

>>but since
>>LCDs use polarization to turn pixels on and off, the current LCS schemes for
>>sequential stereo wouldn't work!  

>****  You're saying that the LCS glasses, that darken and lighten with it's
>own cross polarization to provide sequential operation, won't function with
>an LCD screen? What effect does the screen polarization have relative to the
>view when one side of the LCS glasses is *open*? Does it create color
>distortion, or partial polarity problems, or something else?

When the LCS is "open" the light coming through is still polarized, as is
the light coming through the LCD.

Theoretically, you could make the "on" state of both the display and glasses
have the same polarity and it would work.  But try looking at any kind of LCD
with any kind of polarizing glasses and I think you'll agree that it won't
work.

>>............ Of course, the perfect alignment of pixels on an LCD would
>>make a lenticular display quite possible - in fact, I've seen this done with
>>full motion stereo video.

>****  The idea of using lenticular and LCD is quite interesting. I'd like to
>see such a display in action. What about access to the sweet spot? Is this
>likely to cause headaches from keeping one's head in the right spot?

I think the manufacturer was Sharp, but I'm not sure.  It was just a proto-
type, of course, and I haven't heard anything more about it.  Yes, there
definitely was a sweet spot.  That's why they made it a small screen to be
held by the individual viewer.  The headache problem might be reduced by
the fact that you can turn your and the display together.  It would be great
for 3D video games, but questionable for general stereo TV.  On the other
hand, the scene I watched of a young lady popping out of a swimming pool
in glorious 3D made a pretty good argument for stereo TV!

Greg M.


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