3D TV tech question

Post by r***@vt.edu
So, can anyone tell me what is "special" about 3D televisions?
I mean, what do they have to do to make it compatible? I've
seen 3D broadcast on regular old 4:3 color TVs back in the
1970s or 80s. It seems to me that any TV with sufficient
resolution can handle the 2 color separation type of 3D, so
what is it with these new TVs that has to be different?
As far as I can tell it's still just 2 sets of color images
filtered through colored lenses to give a stereoscopic view,
right?

No. To answer your questions, read through these:

http://www.popsci.com/gadgets/article/2010-01/its-about-time-3-d-comes-home

http://www.3dtvscreen.com/

http://electronics.howstuffworks.com/3d-tv.htm

David Ruether

2010-04-21 18:57:12 UTC

Post by Professor Bubba

http://www.popsci.com/gadgets/article/2010-01/its-about-time-3-d-comes-home
http://www.3dtvscreen.com/
http://electronics.howstuffworks.com/3d-tv.htm

I was recently surprised by two things regarding 3D TV --
1) I liked it (I hated the old two-color 3D technique - it
neither worked very well, and it spoiled the color). It
worked very well and was pleasant to watch.
2) I already spotted some programming material on the
free HD on demand local network(!).
--DR

Andrew Rossmann

2010-04-21 20:47:40 UTC

[This followup was posted to rec.video and a copy was sent to the cited
author.]

Basicaly, 3D HDTV splits the signal into 2 half-res pictures. It uses
shutter lenses to toggle one eye or the other on and off as it displays
one half or the other. The glasses are expensive, about US$100-150 each,
and currently tied to a particular brand or even TV.

The version used for the Masters put the left and right side by side on
a regular TV, reducing resolution from 1920x1080 to 810x1080. I've heard
there is also a top/bottom version, which would cut resolution to
1920x540.

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Gene E. Bloch

2010-04-22 00:02:34 UTC

Post by Andrew Rossmann
[This followup was posted to rec.video and a copy was sent to the cited
author.]

Basicaly, 3D HDTV splits the signal into 2 half-res pictures. It uses
shutter lenses to toggle one eye or the other on and off as it displays
one half or the other. The glasses are expensive, about US$100-150 each,
and currently tied to a particular brand or even TV.
The version used for the Masters put the left and right side by side on
a regular TV, reducing resolution from 1920x1080 to 810x1080. I've heard
there is also a top/bottom version, which would cut resolution to
1920x540.

And how do they get the images to the eyes? IMO, it would require prisms to
place the pictures in appropriate relationship to the eyes...

Do you have a link? I'll also Google (or something) later...

--
Gene E. Bloch

Kevin McMurtrie

2010-04-22 03:44:14 UTC

The old 2 color scheme is long dead.
3D LCD TVs have an alternating polarization pattern on the pixels for
polarized glasses. 3D plasma and DLP alternates frames rapidly for
electronic viewing glasses that alternate transparency for each eyepiece.

It's new because of the bandwidth requirements. Analog NTSC would be a
flickering blobby mess if you split its bandwidth in half. The old
MPEG2 format used for HDTV isn't quite up to the task either. Only a
variation of the newer H.264 compression has enough efficiency to fit
good looking 3D in a standard bitrate.

--
I won't see Google Groups replies because I must filter them as spam

Gene E. Bloch

2010-04-22 03:58:31 UTC

The old 2 color scheme is long dead.
3D LCD TVs have an alternating polarization pattern on the pixels for
polarized glasses. 3D plasma and DLP alternates frames rapidly for
electronic viewing glasses that alternate transparency for each eyepiece.
It's new because of the bandwidth requirements. Analog NTSC would be a
flickering blobby mess if you split its bandwidth in half. The old
MPEG2 format used for HDTV isn't quite up to the task either. Only a
variation of the newer H.264 compression has enough efficiency to fit
good looking 3D in a standard bitrate.

The old 2-color scheme is not long dead, or at least a (possibly new)
variant of it was alive a month or two ago.

That's when I bought a couple of DVDs that came with red-blue glasses. They
produced a half decent 3-D effect with half decent colors (maybe I mean
"assed", rather than "decent", in both cases).

The color was a bit etiolated and the 3-D effect was inconsistent, but
somewhat credible when it was good.

The eyestrain was such that I went back to 2-D to watch the movies
(actually it was "we" - there were two of us, and we agreed it was much
more comfortable in 2-D).

I've seen demos of the new scheme in two stores (two nearby Fry's - or is
it Fry'ses?). It's better than the above, but not tempting yet. One setup
looked very dark and the other looked a little dark. The color and the 3-D
were noticeably improved, but as I said, not tempting.

--
Gene E. Bloch

Kevin McMurtrie

2010-04-22 06:46:21 UTC

The old 2 color scheme is long dead.
3D LCD TVs have an alternating polarization pattern on the pixels for
polarized glasses. 3D plasma and DLP alternates frames rapidly for
electronic viewing glasses that alternate transparency for each eyepiece.
It's new because of the bandwidth requirements. Analog NTSC would be a
flickering blobby mess if you split its bandwidth in half. The old
MPEG2 format used for HDTV isn't quite up to the task either. Only a
variation of the newer H.264 compression has enough efficiency to fit
good looking 3D in a standard bitrate.

The old 2-color scheme is not long dead, or at least a (possibly new)
variant of it was alive a month or two ago.
That's when I bought a couple of DVDs that came with red-blue glasses. They
produced a half decent 3-D effect with half decent colors (maybe I mean
"assed", rather than "decent", in both cases).
The color was a bit etiolated and the 3-D effect was inconsistent, but
somewhat credible when it was good.
The eyestrain was such that I went back to 2-D to watch the movies
(actually it was "we" - there were two of us, and we agreed it was much
more comfortable in 2-D).
I've seen demos of the new scheme in two stores (two nearby Fry's - or is
it Fry'ses?). It's better than the above, but not tempting yet. One setup
looked very dark and the other looked a little dark. The color and the 3-D
were noticeably improved, but as I said, not tempting.

The passive and active glasses use a polarizer, so that's half the light
gone. That light is cut in half again by directing light to only one of
two eyes. It's dark.

There's another technology using an array of lenses and active tracking
to project each frame into each eye. It only works for one viewer so
it's being considered for handhelds. The operation is similar to
children's toys that show 3D using a ridged lens over two images
interleaved together.

--
I won't see Google Groups replies because I must filter them as spam

Gene E. Bloch

2010-04-22 17:47:37 UTC

The old 2 color scheme is long dead.
3D LCD TVs have an alternating polarization pattern on the pixels for
polarized glasses. 3D plasma and DLP alternates frames rapidly for
electronic viewing glasses that alternate transparency for each eyepiece.
It's new because of the bandwidth requirements. Analog NTSC would be a
flickering blobby mess if you split its bandwidth in half. The old
MPEG2 format used for HDTV isn't quite up to the task either. Only a
variation of the newer H.264 compression has enough efficiency to fit
good looking 3D in a standard bitrate.

The old 2-color scheme is not long dead, or at least a (possibly new)
variant of it was alive a month or two ago.
That's when I bought a couple of DVDs that came with red-blue glasses. They
produced a half decent 3-D effect with half decent colors (maybe I mean
"assed", rather than "decent", in both cases).
The color was a bit etiolated and the 3-D effect was inconsistent, but
somewhat credible when it was good.
The eyestrain was such that I went back to 2-D to watch the movies
(actually it was "we" - there were two of us, and we agreed it was much
more comfortable in 2-D).
I've seen demos of the new scheme in two stores (two nearby Fry's - or is
it Fry'ses?). It's better than the above, but not tempting yet. One setup
looked very dark and the other looked a little dark. The color and the 3-D
were noticeably improved, but as I said, not tempting.

The passive and active glasses use a polarizer, so that's half the light
gone. That light is cut in half again by directing light to only one of
two eyes. It's dark.

Yes, I agree - but until they brighten up the displays enough to make up
for that, I am less than tempted.

Post by Kevin McMurtrie
There's another technology using an array of lenses and active tracking
to project each frame into each eye. It only works for one viewer so
it's being considered for handhelds. The operation is similar to
children's toys that show 3D using a ridged lens over two images
interleaved together.

Another thing that might work is putting 3-D into TV spectacles, where you
already have a separate display for each eye. Now we're probably talking
serious money, though. And I imagine it could cause vertigo, unless the
pictures were adjusted for movements of the wearer's head - not likely to
happen, I suspect.

The ridged (cylindrical) lens idea is not only for children's toys. I've
seen it used for religious icons and for ads... :-)

I think the cylinder lens technology could have a succession of sweet
spots, if properly arranged - certainly the children's toys do. Sort of a
vague (VERY vague) analogy to interference bands.

--
Gene E. Bloch

Kevin McMurtrie

2010-04-23 05:48:34 UTC

The old 2 color scheme is long dead.
3D LCD TVs have an alternating polarization pattern on the pixels for
polarized glasses. 3D plasma and DLP alternates frames rapidly for
electronic viewing glasses that alternate transparency for each eyepiece.
It's new because of the bandwidth requirements. Analog NTSC would be a
flickering blobby mess if you split its bandwidth in half. The old
MPEG2 format used for HDTV isn't quite up to the task either. Only a
variation of the newer H.264 compression has enough efficiency to fit
good looking 3D in a standard bitrate.

The old 2-color scheme is not long dead, or at least a (possibly new)
variant of it was alive a month or two ago.
That's when I bought a couple of DVDs that came with red-blue glasses. They
produced a half decent 3-D effect with half decent colors (maybe I mean
"assed", rather than "decent", in both cases).
The color was a bit etiolated and the 3-D effect was inconsistent, but
somewhat credible when it was good.
The eyestrain was such that I went back to 2-D to watch the movies
(actually it was "we" - there were two of us, and we agreed it was much
more comfortable in 2-D).
I've seen demos of the new scheme in two stores (two nearby Fry's - or is
it Fry'ses?). It's better than the above, but not tempting yet. One setup
looked very dark and the other looked a little dark. The color and the 3-D
were noticeably improved, but as I said, not tempting.

The passive and active glasses use a polarizer, so that's half the light
gone. That light is cut in half again by directing light to only one of
two eyes. It's dark.

Yes, I agree - but until they brighten up the displays enough to make up
for that, I am less than tempted.

Another thing that might work is putting 3-D into TV spectacles, where you
already have a separate display for each eye. Now we're probably talking
serious money, though. And I imagine it could cause vertigo, unless the
pictures were adjusted for movements of the wearer's head - not likely to
happen, I suspect.
The ridged (cylindrical) lens idea is not only for children's toys. I've
seen it used for religious icons and for ads... :-)
I think the cylinder lens technology could have a succession of sweet
spots, if properly arranged - certainly the children's toys do. Sort of a
vague (VERY vague) analogy to interference bands.

The sweet spot is only an inch or two wide so the options are skull
clamps or a lens that tracks a single viewer. The former might be
limited to niche markets.

--
I won't see Google Groups replies because I must filter them as spam

Gene E. Bloch

2010-04-23 18:10:16 UTC

The old 2 color scheme is long dead.
3D LCD TVs have an alternating polarization pattern on the pixels for
polarized glasses. 3D plasma and DLP alternates frames rapidly for
electronic viewing glasses that alternate transparency for each eyepiece.
It's new because of the bandwidth requirements. Analog NTSC would be a
flickering blobby mess if you split its bandwidth in half. The old
MPEG2 format used for HDTV isn't quite up to the task either. Only a
variation of the newer H.264 compression has enough efficiency to fit
good looking 3D in a standard bitrate.

The old 2-color scheme is not long dead, or at least a (possibly new)
variant of it was alive a month or two ago.
That's when I bought a couple of DVDs that came with red-blue glasses. They
produced a half decent 3-D effect with half decent colors (maybe I mean
"assed", rather than "decent", in both cases).
The color was a bit etiolated and the 3-D effect was inconsistent, but
somewhat credible when it was good.
The eyestrain was such that I went back to 2-D to watch the movies
(actually it was "we" - there were two of us, and we agreed it was much
more comfortable in 2-D).
I've seen demos of the new scheme in two stores (two nearby Fry's - or is
it Fry'ses?). It's better than the above, but not tempting yet. One setup
looked very dark and the other looked a little dark. The color and the 3-D
were noticeably improved, but as I said, not tempting.

The passive and active glasses use a polarizer, so that's half the light
gone. That light is cut in half again by directing light to only one of
two eyes. It's dark.

Yes, I agree - but until they brighten up the displays enough to make up
for that, I am less than tempted.

Another thing that might work is putting 3-D into TV spectacles, where you
already have a separate display for each eye. Now we're probably talking
serious money, though. And I imagine it could cause vertigo, unless the
pictures were adjusted for movements of the wearer's head - not likely to
happen, I suspect.
The ridged (cylindrical) lens idea is not only for children's toys. I've
seen it used for religious icons and for ads... :-)
I think the cylinder lens technology could have a succession of sweet
spots, if properly arranged - certainly the children's toys do. Sort of a
vague (VERY vague) analogy to interference bands.

The sweet spot is only an inch or two wide so the options are skull
clamps or a lens that tracks a single viewer. The former might be
limited to niche markets.

As I said, the children's toys are configured so that there is a series of
sweet spots every so many degrees. It has to do with the focal length of
the cylindrical lenses, their width, and the spacing of the stripes on the
underlying picture.

--
Gene E. Bloch

Kevin McMurtrie

2010-04-24 02:36:46 UTC

The old 2 color scheme is long dead.
3D LCD TVs have an alternating polarization pattern on the pixels for
polarized glasses. 3D plasma and DLP alternates frames rapidly for
electronic viewing glasses that alternate transparency for each eyepiece.
It's new because of the bandwidth requirements. Analog NTSC would be a
flickering blobby mess if you split its bandwidth in half. The old
MPEG2 format used for HDTV isn't quite up to the task either. Only a
variation of the newer H.264 compression has enough efficiency to fit
good looking 3D in a standard bitrate.

The old 2-color scheme is not long dead, or at least a (possibly new)
variant of it was alive a month or two ago.
That's when I bought a couple of DVDs that came with red-blue glasses. They
produced a half decent 3-D effect with half decent colors (maybe I mean
"assed", rather than "decent", in both cases).
The color was a bit etiolated and the 3-D effect was inconsistent, but
somewhat credible when it was good.
The eyestrain was such that I went back to 2-D to watch the movies
(actually it was "we" - there were two of us, and we agreed it was much
more comfortable in 2-D).
I've seen demos of the new scheme in two stores (two nearby Fry's - or is
it Fry'ses?). It's better than the above, but not tempting yet. One setup
looked very dark and the other looked a little dark. The color and the 3-D
were noticeably improved, but as I said, not tempting.

The passive and active glasses use a polarizer, so that's half the light
gone. That light is cut in half again by directing light to only one of
two eyes. It's dark.

Yes, I agree - but until they brighten up the displays enough to make up
for that, I am less than tempted.

Another thing that might work is putting 3-D into TV spectacles, where you
already have a separate display for each eye. Now we're probably talking
serious money, though. And I imagine it could cause vertigo, unless the
pictures were adjusted for movements of the wearer's head - not likely to
happen, I suspect.
The ridged (cylindrical) lens idea is not only for children's toys. I've
seen it used for religious icons and for ads... :-)
I think the cylinder lens technology could have a succession of sweet
spots, if properly arranged - certainly the children's toys do. Sort of a
vague (VERY vague) analogy to interference bands.

The sweet spot is only an inch or two wide so the options are skull
clamps or a lens that tracks a single viewer. The former might be
limited to niche markets.

Heh, it has to do with the width between your eyes. After all, it is
projecting directly into them to create the 3D effect.

--
I won't see Google Groups replies because I must filter them as spam

Andrew Rossmann

2010-04-23 20:49:52 UTC

Post by Kevin McMurtrie
The old 2 color scheme is long dead.
3D LCD TVs have an alternating polarization pattern on the pixels for
polarized glasses. 3D plasma and DLP alternates frames rapidly for
electronic viewing glasses that alternate transparency for each eyepiece.

I don't think 3DTV uses polarization. It's simply toggling LCD lenses on
the glasses on and off in sync with the screen refresh.

You may be thinking of most movie theaters that use passive polarized
glasses. Modern 3D uses circular polarization and digital projeciton
with high refresh rates to reduce eyestrain and less sensitive to
tilting your head.

--
If there is a no_junk in my address, please REMOVE it before replying!
All junk mail senders will be prosecuted to the fullest extent of the
law!!
http://home.comcast.net/~andyross

Kevin McMurtrie

2010-04-24 02:42:26 UTC

Post by Andrew Rossmann

I don't think 3DTV uses polarization. It's simply toggling LCD lenses on
the glasses on and off in sync with the screen refresh.

LCDs are two polarized films with a liquid crystal between them that can
twist the polarization. Those active shutter glasses lose over 50% of
unpolarized light in the polarization films and over 50% is lost again
from the alternating blanking. Maybe 20% of the original light reaches
the eyes.

Post by Andrew Rossmann
You may be thinking of most movie theaters that use passive polarized
glasses. Modern 3D uses circular polarization and digital projeciton
with high refresh rates to reduce eyestrain and less sensitive to
tilting your head.

--
I won't see Google Groups replies because I must filter them as spam

Pete B

2010-04-23 13:39:25 UTC