3D is going through a cycle of popularity, and it is not clear that it will
last, but this time there seems to be a lot of technical innovation which
has resulted in acceptable presentation to groups. But each method has
problems. So far the best method for home presentation seems to be using
circular polarization to separate right and left images, but it has problems
as all the methods do. So can anyone come up with some ideas for fixing
some of the problems. Here is a list of current methods:
1. Anaglyph - Red/blue glasses. Works on any color monitor, but has
ghosting and results do not look good. OK for comics, but not for good TV.
2. Lenticular/Barrier - Separates R/L using alternate vertical strips, but
only looks good if you look at it straight on, and if to the side you get
severe ghosting and/or reversal of the images. Resolution is not very good.
Only good for 1 viewer.
3. Time division - Active LCD glasses and L/R frames are alternated in
succession with the glasses blocking the unwanted frame. Expensive and
ghosting happens. Some people are nauseated by the flickering. The need to
recharge the glasses is very tiresome, and the glasses tend to be heavy and
expensive.
4. Polarization FPR (Film pattern retarder) - L/R circular polarized light
used to deliver different frames to the viewer. Some resolution is lost,
but your brain puts some of it back. Ghosting is less than the time
division method according to reports I have read, but the viewer has to be
careful about vertical alignment which is often critical within a few
degrees. Off axis horizontally introduces some ghosting, but just being a
few degrees off vertically produces severe ghosting, and there is just one
optimal distance because the picture is divided into alternate horizontal
strips. This is the least expensive method and viewers do not generally
have nausea. In addition the glasses are lightweight and cheap. This seems
to be a growing method and is selling better than #3.
5. 6 color method - Not available at home, but used in some theaters. The
spectrum is divided into 6 regions R1, R2, G2, G2, B1, B2 and the 1/2 colors
are used to present only L or R to each eye. The glasses have fancy
coatings which block the wrong color, and then shift the colors to match for
each eye, according to what I have read. It should have no problem with
ghosting due to being off axis, but the glasses cost $25 each. I have read
that some theaters require you to turn in your drivers license to get the
glasses. I have not read any reports about the quality of the picture or
presence of ghosting.
6. Zscreen, polarization/time division - Not available for home use, but
uses time division at the monitor and produces alternate frames with
opposite circular polarization. No reviews, but suffers from same problem
of ghosting off axis as the FPR system. Ghosting due to persistence may
also occur as in the time division method, but it delivers full resolution.
This is one of the commonly used system in theaters. The other common one
would use 2 aligned projectors with each handling only 1 polarization. It
was being developed for home use, but the economy got in the way and the
company dropped it.
YouTube supports 1, 3, 4 #4 can have either vertical or horizontal
alternating R/L strips. They also support separate images which can be
freeviewed, or viewed with a lorgnette viewer.
So I was thinking about the FPR method, and the main problem is due to the
fact that the alternate horizontal strips have to have good alignment
between the circular polarization filter and the pixels. But when you get
off vertical axis, the light comes from adjacent strips so you get the
ghosting problem inherent in lenticular when off axis. The obvious solution
is to somehow prevent light from each pixel going through the adjacent
strips, but then you will probably have a severe problem with dropoff in
intensity. A reflective barrier might work better. If the light can be
collimated to be horizontal before going through the pixels, that would
help. There are certainly some clever engineers looking at these problems,
but more brains might be able to come up with some great ideas. There was a
very clever system that individually changed the polarization for each
pixel, but it had severe ghosting, especially off vertical or horizontal
axis. The FPR method is currently cheapest, and is fairly satisfactory
except when you want to mix 2D and 3D. It makes 2D small fonts hard to
read. For natural pictures the mind apparently fills in the missing
information for each eye. Each eye receives only half of the vertical
information, but the brain accommodates this. Indeed this is something I
was already aware of because when using 2 eyes my astigmatism in each is at
a very different angle so my brain generates higher resolution than each eye
alone. So I had to get an FPR monitor when my old one died, so I can attest
to the fact that it looks good if you are the right distance from the screen
at exactly the right vertical angle.
Does anyone have thoughts on how to fix some of the existing systems?
Incidentally there have been some reports that 3D tend to help students
remember things better. Whether that effect is inherent in the medium, or
just the novelty is unknown.