A new technology emerges
It took the invention of the liquid crystal display, among other things, to bring usactive-shutter 3-D technology, which is the current state of the art and the basis for most 3-D displays on the market today.
Viewers don glasses with lenses that are actually LCD shutters that can alternate between blocking the left and right eye 120 times per second -- in other words, they alternate at 120 Hz. They then look at a screen that syncs with the glasses to show the appropriate image for each eye. The images don't have blurry fringes or "ghosts" as they do in other systems, and either black-and-white or full-color images can be used.
But there are downsides. For one, between the darkened glasses and the 120-Hz image-switching, the image has its brightness effectively cut in half. This isn't bad if you're already in a darkened room (e.g., a home theater) but can be problematic if you're not. Second, you have to actuallywear the glasses, and that by itself is a distraction -- doubly so for people who already have visual problems or simply find glasses annoying.
And finally, there is not yet a standard for 3-D glasses. So, for example, if you give a party for your kids and want to show a 3-D cartoon on your Sony TV, your kids' friends may not be able to watch the cartoon using the glasses from their Samsung TV. And at $200 a pop, it's unlikely you'll want to buy glasses for the whole crew.
The content crunch
What matters more than the tech, though, is content. Content is king, especially when it comes to 3-D, and right now there's just not very much 3-D video material out there, either live-broadcast or prerecorded.
Many of the barriers in generating 3-D content are both technical and economic. Much as the early years of color created technical challenges for film and TV crews, filming in 3-D requires special cameras and the technical expertise to use them. It's not insurmountable -- people can be brought in and trained on new equipment in fairly short order -- but only makes sense if the demand for 3-D content warrants it.
Of course, there's the possibility of converting existing 2-D material to 3-D. For example, although the recent remake of Clash of the Titans was not shot in 3-D, it did have a 3-D theatrical release.
It's also possible to have consumer equipment perform resynthesize 2-D to 3-D on the fly. Cyberlink's current version of its PowerDVD application comes with a feature called TrueTheater 3D, which allows 3-D video to be derived from a conventional 2-D DVD. Toshiba's series of Cell TVs also promises to convert 2-D to 3-D on the fly but won't be released until later this year.
The problem with either approach is that it requires adding picture information that was never there to begin with, and which can't always be deduced by analyzing a 2-D image (or even a 2-D motion stream). This was one of the problems faced by movie studios when they wanted to convert recent moviessuch as Titans and Alice in Wonderland from 2-D to 3-D. By the experts' own admission, some degree of manual work is required for the technique to really work, which means automatic conversion of 2-D to 3-D by software or hardware is going to yield limited results at best.
3-D: Who needs it?
That brings us to another issue with 3-D entertainment, one that doesn't get as much discussion in technical circles: the aesthetic and artistic problems that 3-D introduces.
The size and detail of most scenes in a movie, especially on a big screen, create a 3-D effect all their own. Add actual 3-D to that, and you have to make a bevy of additional decisions. How often can you cut without disorienting the audience? What do you keep in focus? One thing? Everything? Do you try to make things pop out of the screen or instead sink into it, as director Werner Herzog plans to do with his upcoming 3-D documentary about the Chauvet cave paintings?
Questions like these, plus the technical problems generated by 3-D, prompted movie critic Roger Ebert to pen an essay for Newsweek where he decried theatrical 3-D as a gimmick. It is a way not just to scalp ticket-buyers out of an extra $5 a head, he declared, but also a way to pressure theater owners into buying the next generation of projection hardware. Critic A.O. Scott of The New York Times stated that 3-D seemed better suited to animation than to live-action, and that the "pop-out holographic effects feel more tacked-on" for "earthbound" 3-D films like Alice in Wonderland and Clash of the Titans.
In other words, a good 2-D movie doesn't need 3-D to make it even better, just as a good black-and-white movie isn't crippled by not having color.
Another possible problem with 3-D is medical, not aesthetic. An associate professor of ophthalmology was quoted on CNN.com as saying that about 20% of viewers who watch 3-D content for prolonged periods of time experience vertigo and nausea.
It's possible to blame some of that on what happens when you take fast-moving content better suited for 2-D and try to show it in 3-D: Viewers can't focus or track what's going on in front of them fast enough, and they become ill. 3-D also seems to be that much more problematic for people who have vision problems like strabismus or who are photosensitive epileptics. The strobing effects created by 3-D glasses may not be noticeable to most people, but those sensitive to it can have everything from headaches to seizures. 3-D TV manufacturer Samsung has issued warnings about this.