Re: [Visualpython-users] stereo

[John B. <jb...@te...>]

----- Original Message ----- 
From: <vis...@li...>
> Message: 7
> Date: Sat, 12 Dec 2009 23:26:26 -0500
> From: Bruce Sherwood <Bru...@nc...>
> Subject: Re: [Visualpython-users] Vpython active stereo 3D -- Will it

[dels]
> Even without such a graphics card you can observe the scheme. With
> scene.stereo = 'passive' you get two images on the screen, one for each
> eye. If you use small enough images and are able to look "walleyed" you
> can see true stereo without glasses. Or set screen.stereo = 'crosseyed'
> and view the two images cross-eyed.

This when it finally showed up (I was one of those begging for stereo all 
those years ago...), was much easier than two windows and rotating the 
object.....   It also solved all problems regarding how to control both 
windows' images simultaneously with the mouse.  I made *extensive* use of 
the new stereo method before Python's inherent speed (low) forced me to C++ 
and OpenGL.
Now:

> I don't see why the Acer would show alternate frames. Since there is

I understood the OP was describing an *interlace* method (one I'd never 
thought of, polarizing alternate *horizontal* lines).
[dels]

> You say that they've chosen to have horizontal lines polarized, yielding
> 1366 x 384. This seems odd; if they polarized vertical lines the
> resolution would be 683 x 768, which would seem to me to be a more
> reasonable choice.
> Bruce Sherwood

I suspect an holdover from CRT scan lines (which is even still present in 
HDTV).  There essentially *are no* "vertical lines" on a TV or monitor. 
Images are (TMK) still presented to the monitor as horizontal scan lines, 
even though they are now digitally created.  Due to the literal electronic 
impossibility of drawing on the screen "simultaneously everywhere," images 
are drawn on screen serially, left-to-right, top-to-bottom, much the same 
way they were with CRT TVs an monitors.  The only difference I'm aware of is 
that now the CCD-like "bucket brigade" method is used, of reading-out the 
video memory buffer.  INstead of a moving-continuous-analog electron beam 
scanning the screen, it's now pixels being addressed sequentially, but with 
the same "scanning" principle.  Thus, there's really no such thing 
(electronically/video-displaying) as "vertical lines."  Perhaps in future if 
Acer's experiment flies, stereo/polarizer methods will appear that do 
deliberately break up the screen by pixels instead of by horizontal lines.
(Old TV repairman here; my info could be out of register with digital 
technology, but I am rather sure that HDTVs and digital monitors still 
employ a form of "scanning" to get images onto the screen.)

jbr...@ch...