How to do 3-D
3-D Film Theory
3-D Film List
3-D Film Review
3-D Camera Build
21st Century 3-D
The world television audience is lazy and cheap by definition (bear in mind that most people don't even change out-of-the-box TV settings or even know how to), so you'll have to start thinking about a way of showing 3-D stereoscopic images without complicated or expensive extra's and procedures - like electronic glasses.
So that's the playing field. Now this does leave some options open for consideration. Let's look at some of the available 3D encoding techniques and their employability with current TV technology. Again, realism dictates that your ultimate choice depends on your means and goals; the bigger the audience, the cheaper the glasses need to be and the longer the film lasts, the better the 3D needs to be to prevent a massively headache with your audience.
The latest technology
But what about the latest Philips, Samsung and Mitchubishi 3-D (DLP) TV sets? It will be a while before they penetrate the average Eropean and American living rooms. If the 3-D revolution really takes off beyond 2010, it will be another 10 years before new technology such as native 3-D TV truely reaches the global living room - or even just the western world. What's worse, Philips and Samsung have just pulled out of the 3-d TV market again and Mitsubishi sets are not available in Europe. Hitachi has then just entered the 3-D TV market, but without proper 3-D broadcast content, sales will remain very steadily low and unprofitable for TV manufacturing giants. It's a bit of a chicken and egg situation, and right now the chicken is not laying enough eggs.
If you're planning for future 3-D broadcast TV production (something that will work and reach enough households in 2025), or if you're planning to produce for a small number of special 3-D TVs, the Philips and Samsung screens are indeed ready to display your Stereoscopic ideas - with or without the glasses! The best bet, what ever you do, is to shoot two separate videos for left and right and decide in post how it's going to be presented (lenticular or field/frame sequential).
Regarding the 3-D TVs that do exist right now: they are ideal for special presentations, advertising in public spaces and other promotional use. The freeview models work with Lenticular presentation (see below) and some of the newest screens work with Shutterglasses and Polarized glasses (again, see below).
The working principle of polarizing light
You know you want it: the smoothest, most reliable 3-D image system on your television. Polarized 3-D on TV is by far the best solution - when it comes to wearing glasses. However, the premise of the ray tube or LCD screen found in television sets, rules out any standalone practise of the polarized system; the polarized system works only when the 3-D image is, well, polarized by two oppositely polarizing lenses. So the light needs to be projected.
A setup with two identical televisions and a semi-transparent mirror can be used, but the source (the 3-D on tape or from broadcast) has to be split or a special splitter box has to split side-by-side or field-sequentially encoded 3-D imagery.
Polarized 3-D is best known for the big theme park films like 'Terminator 3-D', 'The Amazing Adventures of Spiderman' or 'Captain EO' (That one was replaced by 'Honey, I shrunk the Audience' in 1999) and, in DLP enabled cinemas, 'Chicken Little'. It is being used in these parks and DLP cinemas because it produces the best possible results in 3-D.
Besides the clunky solution illustrated below, 3-D Flatscreen Plasma TVs are now available that use two screens behind each other, with sheet polarizers, turning on and off at high framerates to give the glasses-wearing viewer a smooth and spectacular 3-D experience.
Chromadepth is a system that works with difference in
hue; the visual spectrum- with colours running from red to blue.
When presenting moving images in Chromadepth, this results in something that resembles an LSD trip. If you can live with this colour design, then ChomaDepth is probably the best system for cheap, accessible 3-D television production.
The Pulfrich system is quite an interesting solution. It works just fine, as performed on a broadcast of '3rd Rock from the Sun' by NBC and 'Shark Week' on Discovery Channel. The problem is, as is indigenous with Pulfrich 3-D, the camera has to keep on moving for the effect to work. In short, it works on the combined premise of delayed image transfer to the brain -the eye with the darkened glass- and horizontal parallax -moving sideways, one eye will see equal imagery later than the other eye, creating the illusion of depth.
When people thought of the future of 3-D in the 80's and 90's, they thought of shutterglasses. Because they look futuristic and because the IMAX uses them for some of their cinemas (the others that are 3-D enabled use polarized glasses).
The shutterglass - or VR - system is also a great option for 3-D imagery on television. But your audience has to be willing to spend the money on expensive VR goggles or relatively less expensive shutterglasses. Tthat means one pair for every family member.
The new Samsung and Mitsubishi 3-D DLP TV sets use frame sequential 3-D encoding on high framerates of 60 fps - that's 60 progressive frames per second (120 Hz). The same field/frame sequential glasses as those used from the 80's onward are compatible with these new 3-D TV sets.
Field/frame sequential glases / VR goggles have an LCD display for each eye, and the shutterglasses work by opening and closing the left and right eye glass in sync with the field interlacing a television does (field sequential). This means that the viewer will see a substantial flicker - somewhat less on NTSC than on PAL or SECAM because NTSC works on 60 fields per second, while PAL and SECAM work on 50 fields per second. 100 Hz televisions do not work with the shutterglass system, nor do plain HDTVs.
Ideally, a 3-D television presentation would be one where the viewer does not wear glasses at all. In other word a freeview solution. This sort of a television exists and it employs the lenticular method.
The surface of this television contains a specially ribbed lens that allow the left and right eye to see different angles of the image on the screen, which is parted into lots of small strips to match the ribs of the lens on the screen. This surface can also be a plastic sheet add-on.
The resolution of the screen will drop dramatically, because of the left and right image next to each other (even/odd vertical lines) on one screen. For example, a 1024x768 image on a computer monitor will be reduced to 438x256 (less than 1/4 of the screen). So one will need a screen of very high resolution to maintain normal resolution 3-D imagery. Standard Definition TV currently works with a resolution of 720 x 480 for NTSC and 720 x 576 for PAL and SECAM. True HDTV increases the horizontal resolution to 1920x1080, resulting in a final image of 820x360.
In other words: freeview plasma 3-D TVs can result in a bit of a blurry image.
Another version on this theme implies the use of a fresnel lens, dispersing the TV or computer monitor information by directing left eye image information to the left eye and right eye information to the right eye by means of positioning the viewer in a exact position in front of the TV screen (and, indeed, the fresnel lens). Again, a low resolution 3-D image will result as a cause of the low image resolution that all TVs start off with. The fresnel lens is a very popular item with manufacturors and inventors of autostereoscopic 3-D displays because of its light bending properties.
For people who've seen holographic technology featuring in Star Trek,
Star Wars, Logan's Run, Minority Report, A.I. and countless other movies
there's an important reminder of the kind of films they are: science fiction.
The theory that a holographic imaging system may become reality in 100
years time doesn't mean its technology is actually around the corner right
True, there are ongoing experiments with electron beams that make the
electrons flare up at a certain point in space, with a certain colour,
but sticking your hand in such a beam would mean definite electrocution.
Besides, these are highly limited, theoretical lab tests.
Another kind of freeview 3-D technique is the spinning surface approach. By projecting onto a spinning surface with multiple viewing angles, a walk-around image can be generated in the containing cube. Again, this technique is still in its very infancy and practically speaking, is totally unrelated to Television. A future application of this technique will look like a big glass cube in the middle of your living room, requiring the complete bandwidth of your current satellite, cable or digital antenna to transmit one broadcast channel. The end result will be a bit like miniature theatre in your living room.
Also, reports in newspapers of holographics using 'dry ice' as a means of displaying a 3-D image are highly exaggerated and often journalists hungry for news wrongly interpret these experiments as the arrival of the future. A practical application of dry ice in our living rooms or in a cinema theatre is difficult to imagine.
A third common misunderstanding is that the technology behind picture holographics can be used to produce a holographic 3-D movie. The technological restraints of the production of a holographic print actually make this completely impossible with current technology. Required bandwidth for holographic display is so insanely big, that current and next generation technology is not able to transmit a moving holographic image larger than a pinprick.
One has to make a clear distinction between stereo 3-D and holographic 3-D imagery. They are different mediums. Why? Because holographic 3-D (including the 360-Degree Light Field Display imagery) has no framing, as opposed to stereo 3-D.
© 2009 3-D Revolution Productions