Re: [photo-3d] field sequential 3D

[Mike Kersenbrock <michaelk@xxxxxxxxxxxx>]

Stephen Rumbaugh wrote:
> 
> Has anyone heard of "field sequential" 3D? How does it work?
> 
> Steve Rumbaugh

On a TV set, images are done in interlaced fashion.  Each image
is displayed by having the first scan of the screen doing "every 
other line" then the second scan that finishes off the image
by doing the lines skipped in the first scan.  More or less.

Each of the scans is a "field", consisting of half the image.
In "field sequential" 3D, one scan has the left image and the
other scan has the right image.  Of course, each image now
has half the resolution but there are twice as many images!

Least expensive way to look at the F-S 3D tapes one can 
purchase is to use LCD glasses that sync to the TV fields
showing the left image only to the left eye, blocking the
screen from the right eye while the left image is on the
screen.  And vice versa.

Only trouble with that is that each eye is seeing an image
half the time and a black screen half the time (not to 
speak about the image being painted during the time it's
not blacked out).  Ends up being "headache city" due to
heavy-duty flickering of the image.  For most people anyway.
I have a pair of Vrex goggles which are nice in that they
are wireless, but they do flicker tremendously.

This can be improved by expensive equipment and monitors that
double the scan rate of the TV signal so that when it's
halved by the LCD goggles, each eye sees much less flicker.

There is a way to have *completely* flicker-free viewing 
albeit now without some limitations of it's own.  This
is to use the style of VR goggles that have two little
LCD TV sets in it, a separate one for each eye.  I was
given this tip by Elliot Swanson when I spoke to him
last spring in Puyallup.  Specifically, the i-glasses
3D models work very nicely -- I've purchased two of them
on ebay.  They are available new (see http://www.i-glasses.com)
for about $600, possibly less in package deals, or used as
I got them.  The company which originally made them went
under, but the assets of that company were bought by the
company in California at that web site (according to that
web site).

The i-glasses 3D have two 3D modes selected by a switch on
the glasses (which have built-in headphone sound as well).
The switch puts it in to the mode where one field is on the
left and the other on the right.  The other 3D mode swaps
which field is left and which is right.

In any case, no flicker at all because each eye is seeing 
a continuous image.

On the downside, even used on ebay they're still not exactly
cheap.  And more importantly, the image isn't the greatest
quality wise. Resolution is only 180,000 pixels per eye 
which is two thirds of VGA resolution.  Usable, but not
great.  NTSC video isn't the greatest, but probably is
better than that.  There is a 360,000 pixel i-glasses, but
it doesn't have 3D modes.  Sony and Olympus have similar
sorts of glasses that just came out, but they have the
same resolution (180K pixels) and no 3D (but same prices!).

That said, I'm delighted with them!  3D video has been 
a new "toy" only within the last few months, so my selection
of tapes has room to grow, but there's many a movie I don't have
a copy of yet.  Hope something still is "in print"!  :-)

Mike K.