1. What is 3D TV?
3D TV is a generic term for a display technology that lets home viewers experience TV programs, movies, games, and other video content in a stereoscopic effect. It adds the illusion of a third dimension, depth, to current TV and HDTV display technology, which is typically limited to only height and width ("2D").
2. How does 3D TV work?
A 3D TV works much like 3D at the theater. A screen showing 3D content displays two separate images of the same scene simultaneously, one intended for the viewer's right eye and one for the left eye. The two full-size images occupy the entire screen and appear intermixed with one another--objects in one image are often repeated or skewed slightly to the left (or right) of corresponding objects in the other--when viewed without the aid of special 3D glasses. When viewers don the glasses, they perceive these two images as a single 3D image, a process known as "fusing."
The system relies on a phenomenon of visual perception called stereopsis.
The eyes of an adult human lie about 2.5 inches apart, which lets each
eye see objects from slightly different angles. The two images on a 3D
TV screen present objects from two slightly different angles as well,
and when those images combine in the viewer's mind with the aid of the
glasses, the illusion of depth is created.
3. How is the new 3D TV technology different from older 3D?
Most people are familiar with the old anaglyph method, where a pair of glasses with lenses tinted red and cyan (or other colors) is used to combine two false-color images. The result seen by the viewer is discolored and usually lower-resolution than the new method.
The principal improvements afforded by new 3D TV technologies are full color and high resolution--full 1080p HD resolution for both eyes in Blu-ray 3D, for example, and half that resolution in broadcast 3D used by DirecTV and other providers. Note that current passive 3D TV technology affects adversely resolution (see #5).
(Note: For the remainder of this article, any mention of "3D" refers
to the new full-color version, not the old anaglyph variety.)
4. How is 3D TV different from 3D in the theater?
Many viewers have experienced newer 3D presentations, such as IMAX 3D, in movie theaters. Though the technologies can differ somewhat--most U.S. theaters use passive glasses, for example (see #5)--the main practical differences between 3D TV in the home and theatrical 3D are the size of the screen and the distance you sit from it.
In the home the image is generally much smaller, occupying a lower percentage of viewers' fields of vision, so it's generally less immersive. With 2D you could create a more immersive home theater by sitting closer to the screen, but with 3D that can become a problem. Panasonic recommends a seating distance of no closer than 3x the screen height away--about 6.2 feet from a 50-inch screen--and cautions that sitting closer could increase the risk of eye fatigue and headaches. One expert we talked to, Martin Banks of UC Berkeley, confirmed that sitting too close to a 3D screen can heighten the risk of such adverse effects (see #7).
Smaller screens may also present other issues unique to 3D, such as a relatively narrow viewing distance range. We've also seen that the edge of the image, which is much more noticeable with smaller screens, can disrupt 3D viewing much more disconcertingly than 2D.
One advantage of 3D TV at home as opposed to the theater is user control. Some 3D compatible TVs provide control over the 3D experience in addition to standard picture settings. Samsung's models, for example, allow you to adjust the "G axis," or the amount of 3D effect, to taste, comfort or to compensate for variations in eye spacing.
5. What's the difference between active and passive 3D?
Most 3D TVs use active liquid crystal shutter glasses,
which work by very quickly blocking each eye in sequence (typically 120
times per second) to separate the different right and left images
required for 3D. The glasses, in addition to the liquid-crystal lenses,
contain electronics and batteries (good for 80 or more hours and often
rechargeable) that sync to the TV via an infrared or (in many 2011
models) RF signal. They currently cost $60-$120 per pair when sold
separately.
In 2011 Vizio, LG and Toshiba will introduce 3D TVs that use passive polarized 3D glasses that are much less expensive. They are actually compatible with the passive 3D used in theaters, and will work with Real D's circular polarized glasses, for example, which are available for as little as $5 each online. The 2011 models use a technology called Film Pattern Retarder, developed by LG, where a polarizing film coating the TV screen allows each eye to view every other line. See #31 for our impressions.
At CES 2011 Samsung and Real D announced RDZ, a system that claims to deliver full resolution yet allow the use of cheaper passive glasses. Products with this or similar technology won't be widely available in 2011, however.
3D TV is a generic term for a display technology that lets home viewers experience TV programs, movies, games, and other video content in a stereoscopic effect. It adds the illusion of a third dimension, depth, to current TV and HDTV display technology, which is typically limited to only height and width ("2D").
2. How does 3D TV work?
A 3D TV works much like 3D at the theater. A screen showing 3D content displays two separate images of the same scene simultaneously, one intended for the viewer's right eye and one for the left eye. The two full-size images occupy the entire screen and appear intermixed with one another--objects in one image are often repeated or skewed slightly to the left (or right) of corresponding objects in the other--when viewed without the aid of special 3D glasses. When viewers don the glasses, they perceive these two images as a single 3D image, a process known as "fusing."
Here's an example of what 3D looks like without glasses. Notice the doubling of onscreen objects.
(Credit:
Sarah Tew/CNET)
3. How is the new 3D TV technology different from older 3D?
Most people are familiar with the old anaglyph method, where a pair of glasses with lenses tinted red and cyan (or other colors) is used to combine two false-color images. The result seen by the viewer is discolored and usually lower-resolution than the new method.
The principal improvements afforded by new 3D TV technologies are full color and high resolution--full 1080p HD resolution for both eyes in Blu-ray 3D, for example, and half that resolution in broadcast 3D used by DirecTV and other providers. Note that current passive 3D TV technology affects adversely resolution (see #5).
A pair of "active" LC shutter glasses, the most common type for 3D TVs.
(Credit:
Sarah Tew/CNET)
Many viewers have experienced newer 3D presentations, such as IMAX 3D, in movie theaters. Though the technologies can differ somewhat--most U.S. theaters use passive glasses, for example (see #5)--the main practical differences between 3D TV in the home and theatrical 3D are the size of the screen and the distance you sit from it.
In the home the image is generally much smaller, occupying a lower percentage of viewers' fields of vision, so it's generally less immersive. With 2D you could create a more immersive home theater by sitting closer to the screen, but with 3D that can become a problem. Panasonic recommends a seating distance of no closer than 3x the screen height away--about 6.2 feet from a 50-inch screen--and cautions that sitting closer could increase the risk of eye fatigue and headaches. One expert we talked to, Martin Banks of UC Berkeley, confirmed that sitting too close to a 3D screen can heighten the risk of such adverse effects (see #7).
Smaller screens may also present other issues unique to 3D, such as a relatively narrow viewing distance range. We've also seen that the edge of the image, which is much more noticeable with smaller screens, can disrupt 3D viewing much more disconcertingly than 2D.
One advantage of 3D TV at home as opposed to the theater is user control. Some 3D compatible TVs provide control over the 3D experience in addition to standard picture settings. Samsung's models, for example, allow you to adjust the "G axis," or the amount of 3D effect, to taste, comfort or to compensate for variations in eye spacing.
5. What's the difference between active and passive 3D?
Vizio's passive glasses are comparatively thin, light and inexpensive.
(Credit:
Sarah Tew/CNET)
In 2011 Vizio, LG and Toshiba will introduce 3D TVs that use passive polarized 3D glasses that are much less expensive. They are actually compatible with the passive 3D used in theaters, and will work with Real D's circular polarized glasses, for example, which are available for as little as $5 each online. The 2011 models use a technology called Film Pattern Retarder, developed by LG, where a polarizing film coating the TV screen allows each eye to view every other line. See #31 for our impressions.
At CES 2011 Samsung and Real D announced RDZ, a system that claims to deliver full resolution yet allow the use of cheaper passive glasses. Products with this or similar technology won't be widely available in 2011, however.
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