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The Renaissance of 3D:
How the New 3D Technologies Work

Bill Livolsi, February 5, 2010

Interference Filter 3D

Another implementation of 3D in commercial theaters uses a technology called interference filters, made by the German company Infitec. This system uses one projector and does not require a silver screen. Infitec 3D compatible projectors have a special color wheel inserted between the lamp and the imaging device itself that divides the primary colors into discrete sections. Think of it this way: where there once were red, green, and blue, there are now red-1, red-2, green-1, green-2, blue-1, and blue-2. Special interference filter glasses allow the left eye to see only the "1" sections while the right eye sees only the "2" sections. The glasses use additional filters to correct color perception so what your eyes see is as close as possible to the original film. You may have seen this technology already: it is known as Dolby 3D in commercial cinemas.

Dolby 3D is not nearly as widespread in cinema projection as polarized 3D systems are, but the world premiere of Avatar at the Empire Cinema in Leicester Square, London, was shown in Dolby 3D.

Advantages of Interference Filter 3D

Passive glasses. Passive glasses are a common element in 3D systems designed for commercial theaters and other large venues both for their ease of use and for their relatively low cost. Interference filter 3D glasses are more difficult to produce than are polarized glasses. As such, they are built to last. The lenses are made of glass and the heavy-duty plastic frames even have a slot for an anti-theft device. They are more resistant to scratches and scuffs than the more flimsy polarized lenses.

No silver screen. Several decades ago, silver screens were used for all movies, but they fell out of favor. Silver screens have more restrictive viewing angles than do white screens, so when projectors became bright enough to light up a white screen sufficiently, silver screens fell by the wayside.

What was true about silver screens then is still true now: brightness falls off significantly for viewers sitting off-center. In a commercial theater this can include a significant portion of the audience. Since interference filter 3D does not use polarization it does not need a silver screen, thereby improving the viewing experience for everyone in the audience. People along the sides of a theater get more consistent screen illumination while everyone in the audience gets color fidelity on par with non-stereoscopic film.

Disadvantages of Interference Filter 3D

Light loss. Any single-projector 3D display method suffers from significant light loss compared to 2D display on the same projector. This does not mean that single-projector interference filter and polarizer systems are always the same brightness, or that dual-projector implementations are always brighter than single-projector systems. Single-projector polarized systems, interference filter systems, and shutter glasses systems all share this limitation.

Specialized equipment. It is possible to install a single-projector polarized system like RealD on an existing DLP Cinema projector, which many commercial cinemas already use, without actually altering the projector itself. Since the Infitec 3D mechanism works inside the projector, theaters need to either purchase cinema projectors pre-fitted with the Infitec color wheel or have the wheel installed inside their existing DLP cinema projectors by a trained engineer.

Expensive glasses. The major advantage of passive glasses is that they are inexpensive, so one might expect Infitec 3D glasses to be inexpensive as well. They are not. Most of the manufacturing cost of Infitec glasses is in the lenses themselves - the glass must be given several coatings to help them differentiate between the wavelengths used. The most recent Dolby press release related to 3D glasses has their wholesale price at $27.50 per pair. Obviously this represents a significant expense to a participating theater, so great lengths are taken to ensure the glasses are safely returned by theater patrons. One Dolby 3D theater I attended required that I hand over a picture ID in exchange for the glasses.

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Polarizers
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Shutter Glasses
Contents: What is 3D Anaglyph Polarizers Interference Filter
  Shutter Glasses Conclusion
Comments (19) Post a Comment
Currious Posted Feb 5, 2010 5:41 PM PST
So what about glasses-less 3D TVs?

Some companies claim they have that techno in store, from a flat screen.

One easy way to generate 3D that has been done, is to use a fast rotating screen, and as it turns display different pixels for that 3D position.
DD HT Lover Posted Feb 6, 2010 7:00 AM PST
Another fantastic article. Thanks for keeping us ahead of the curve again.
Paul Posted Feb 6, 2010 12:34 PM PST
When special glasses are no longer required, I'll be interested.
Matthieu Posted Feb 8, 2010 6:10 AM PST
Wow you did your homework VERY well. I'm into the 3D photogrphy for a long time and still I learned some things about tech stuff from yur review.
MREUM Posted Feb 10, 2010 9:31 AM PST
I still think 3D is a fad, just like before. People will tire of it, particularly if the 3D films are no better than what has already been produced. Until a system emerges that does not need glasses I do not see it being anymore than a novelty, although the adolescent gaming crowd will probably like it.
willdao Posted Feb 11, 2010 3:03 PM PST
Bill,

Very nice, comprehensive article!

Will
Wyatt Posted Feb 12, 2010 11:35 AM PST
As someone who has been working on a 3D film for the past year now and has experienced looking at the same material with all technologies (except for Interference3D), I can tell you that a good pair of shutter glasses is the best way to go.

I am sensitive to 3D cross-talk and the shutter glasses eliminate this completely for a crisper / cleaner looking image. Another advantage is that you do not have to keep your head on a level plane, so if you wanted to lay down on the couch with your head cocked sideway, shutter glasses would still work as intended. Polarized glasses do not stand up well to this.

Hopefully shutter glasses win the format war and will be mass produced making them much more affordable than they currently are.
libair Posted Feb 15, 2010 1:09 AM PST
well i think that it will take a long period before we see broadcasting in 3d although in korea this technology is here experimentally of course!!so its difficult for me who bought an hdtv this summer to participate in this even if this is 2-3 years ahead!!without the display that is capable of 3d you can only dream of 3d movies!does anyone know if there is a possibility for a top video box lets say to convert hdtv to 3d ready???of course not the 60hz but the 120hz or 200 hz ones...would that be possible!!from the other side here in grece where i live we will have the h.264 in a couple of months so i think the 3d broadcating about a century ahead!!!
Roy Posted Feb 16, 2010 11:56 AM PST
Very informative article. Thanks!

Because "3D Vision" glasses are another $200 on top of the cost of the projector, is it possible ProjectorCentral might consider a combo/package/bundle price where a person could buy say the new ViewSonic 3D projector + Nividia 3D Vision for a package price of around $500?
Jeff M. Posted Feb 22, 2010 9:41 PM PST
I don't know about the rest of you but I am ALL about 3D! If anyone on here could help me, my email is kraftmacincheese@yahoo.com I have been scowering reviews and the like in the search for a 3D projector with the crispest video that 3D projectors can offer. I am going to be throwing a distance of about 10 feet and trying to fill up a 110" screen as much as possible in a 16:9 or similar ratio. I have my eyes on the Epson 8500ub because of the awesome 200,000:1 contrast however it does not have 3D capabilities. So can anyone help me with this. I am trying to find the absolute BEST 3D projector on the market that I can get for around 3000 or so. However I am afraid that the image won't be crisp for movies and games like on one that has a contrast such as the Epson. I am a noob to projection and all of that but am computer literate so you don't have to speak slowly lol :P Thanks everyone.

Jeff
Stunko Posted Apr 8, 2010 9:17 PM PST
The current round of 3D hype will be dead inside of 24 to 36 months.... and will be resurrected some time later again... and again... and again.
Vincent Posted Apr 12, 2010 8:41 PM PST
In the 3D race, seems like the LCD/Plasma TVs are a little faster than projectors. Please correct me if I am wrong. Some of the TVs such as Samsung already supports 3D BlueRay directly (i.e. supports HDMI 1.4 format). Most data/home projectors only support HDMI 1.3 (1080P but not 3D). HDMI 1.4 is a relatively new standard.

Second problem is that it seems that only DLP projectors can support 3D projection. LCD based projectors cannot refresh at 120Hz. So quite a number of brands of projectors will not be able to get into the bandwagon so quickly.

For those looking for 3D experience using a projector and at 1080p, I guess the projectors will only be available some time later this year.
Richard Posted Apr 25, 2010 10:32 AM PST
I'm curious about one other thing. Isn't the end user dependent on the kind of coding that appears on, for instance, a Blu-Ray disk? Will these disks contain all the various encoding schemes, or what? Will I have to shop carefully, noting the kind of technology present on a specific disk before I buy it? If so, the media producers can quickly determine what standards will be weeded out, and buying anything now is premature. Just like VHS and Betamax all over again.
Bob Posted May 29, 2010 7:51 AM PST
So, if my projector refreshes at 120 Hz already, what is the prognosis for an interface box to decode Blu-ray 3D signals interlaced at 60 Hz for left and right eyes and providing the synchronization signal for the shutter glasses?
mdf Posted Jun 2, 2010 10:03 AM PST
Glasses-less 3D will never happen with current displays or projectors. In order for 3D to work, your right eye and your left eye have to see different images. If you shift a few inches to the right on your couch, how could your left eye not see what your right eye had been seeing? Until there are non-static holographic displays (there aren't and no one is working on them) the laws of physics make a glassesless 3D technology completely impossible.
Yllon Posted Jun 20, 2010 4:59 AM PST
This is not exactly true. Hitachi as come up with a way for you to see 3D with out the glasses. It is called parallax viewing. While this format is a year or two away and is only available in flat panels we will eventually see 3D with out glasses.
theG Posted Oct 10, 2010 7:38 AM PST
Bob, "Glasses-less 3D will never happen" check out [sales link deleted] and what about the 3D Nintendo DS?

Anyway, i dont mind the RealD glasses which will go with my realD projector next year... i hate sgutter glasses tho, expensive and you can see the flickering..
Esther Posted Jul 20, 2011 9:26 AM PST
what exactly do the 3D glasses given out at the movie theaters do? does anyone see a future of 3D movies without the glasses? is it likely that the glasses-less 3D showing technology will ever become commercialized enough to be used as widely as regular 2D tvs that most ppl have in their homes?
Carlos Zacharias Posted Sep 2, 2011 6:00 PM PST
What is the diference: 3 D READY AND 3D? Ex.: Optoma D33 and D66. Whych one is abble to project 3D movies riht now?

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