In this article http://www.straightdope.com/classics/a1_369.html Cecil mentions different color lenses.
Other ways have been introduced (tho they still rely on showing each eye slightly different images)
One is to use different polarization for each eye. This was used for many movies when the 3-D fad hit in the mid-80s (Jaws 3D)
Another is to use electrical shutters to alternatively block each eye. The disadvantage is that the frame rate is halved.
Brian
Despite Cecil’s contention that 3-D without glasses isn’t practical, I understand that there has been a theater in Moscow showing such “lenticular” 3-D movies for many years. I don’t know why no one’s ever built another one. I learned about this from the book Amazing 3-D (1982). I know that there are patents on lenticular 3-D TVs, but no one’s built one yet.
You can also make true holographic movies. I’ve seen one at the (now departed) Museum of Holography in New York several years ago. The film was a very short loop of bottles rotating – boring, but there’s no reason that you couldn’t make a “real” film this way. The problem is that your hologram in this case is the screen. I saw a film of people watching a hologram movie several years ago (that’s a complicated sentence, but I think it makes sense). The hitch was that only four people could watch it at a time. No commercially practical, indeed.
When I read Cecil’s column I thought about the non-coloured glasses which I assumed used different polorization for each eye.
My question about this is how are the two different images projected so that they are only picked up by a single polorization lens?
Twin projectors (or a single split-image projector) with different polarization filters, of course.
Some holographic movies have been used as effects at, e.g., Disney World. But there are color and resolution problems for theatrical usage.
I suspect that lenticular projection also has resolution problems. In any case, offhand, I think it would have to be rear projection, which demands a purpose-built building.
The Moscow lenticular system is, indeed, in a building (and with a system) built specifically for that purpose.
I can imagine ways to do it front-projected as well as rear-projected. I don’t know what they use.
Incidentally, the 1950’s 3-D movies were released as polarized systems in the big cities, not the red-and-green (anaglyphic) system everyone associates with 3-D films. The problem is that you need a special p[rojector setup and a screen that won’t scramble your polarization. It was easier to do anaglyphic 3-D – you can use an ordinary projector and screen. The problem is that color movies generally don’t look as good in anaglyphic as in polarized.
Interesting tidbit: One would suspect that 3-D movies got their start with the development of sheet polarizers by Edwin Land. But there was a boom of 3-D movies back in the silent days (!) They didn’t use anaglyphic lenses, either – the earliest 3-D movies used something very much like the modern switching lenses trick. Only they used special rotating discs that you held up in front of your eyes. It was a clumsy and expensive system, though, and didn’t go anywhere. Synchronization must have been a bitch!
There are actually computer screen 3D systems that use the modern equivalent of this system. The lenses are alternatingly turned dark/clear for each eye, while the image on the screen is synced to provide the image to the corresponding eye. IMHO, a great way to get a headache.
I like VR type glasses, with sep. miniature displays for each eye. A nice “wow” effect.
There are also glasses that twist your vision a bit so that each eye sees only one half of the screen. But that has the obvious disadvantage of reducing screen real-estate.
Another would be image alignment. In an ordinary movie theater, if your projection is a little bit off-center, no harm done. But with a lenticular system, you have to line up to the grid, so a few millimeters off would destroy your 3-d effect, and either blur everything not in the plane of the screen, or reverse the depth perception (or a mixture of both).
It’s an ancient thread, but it has “3D” in the title, so it might grab some attention.
I was sifting through some old images in my computer, and came upon this one. It’s a red-green anaglyph that I made from a flat picture in a newspaper, simulating depth by shifting parts of it around. This was at least 20 years ago. The program I used was Paintshop Pro. And what I came up with works remarkably well. I really had little experience with image editing, but somehow I made it work.
If you have some old red-green or red-blue glasses, you better dig 'em out now! Prepare to be startled.
Ahhh! I’m being kicked in the face with a sneaker!