How do 3D TV's work?

[asterion]

I have a LG 47LW5600 3D TV. It’s a passive 3D TV, which means that, as mentioned earlier, the glasses are a heck of a lot cheaper and they work with some 3D movies in theaters. Even better, you can get clip-ons that work with both the TV and at the movies, which is much more comfortable. My 3D source is a Playstation 3, and I mostly use it for 3D gaming, although I have bought a couple 3D BluRays. I used to pay TimeWarner Cable for the 3D tier when they were promising that they’d get more material. I stopped because I was paying $11 a month for ESPN3D and only ESPN, and there wasn’t enough programming to justify it. The 3D channel for the Olympics was free, but again, the coverage was hit-or-miss. On the plus side, it was the feed from the BBC, so it was much more pleasant than most of NBC’s coverage.

3D gaming can be really fun although it takes some getting used to.

[Student_Driver]

@enomaj

FoieGrasIsEvilWith active the TV refreshes @ 120 Hz so that alternating frames give each eye 60 Hz just like regular tv. Student Driver describes passive technology in his first post. For LG Cinema 3d, it used to mean that resolution was cut in half for each eye to 1920x540p instead of 1920x1080p. Since they’ve updated their algorithm, it was increased to 1920x1080i.

There are 240 and 480 Hz active sets, too, so the “downgrade” for each eye would be 120 and 240Hz respectively.

I went with passive (LG) due to lower overall barrier to entry at relatively low trade-off in quality. Unless you get a deal with active to get glasses bundled in, you generally have to pony up an extra $100 to get your first set of glasses, and buy more glasses for additional viewers. For passive, the glasses are practically free (I’ve had to tell friends to stop giving me their theatrical glasses). In addition, I wanted 120 Hz or higher for each eye (noticeable when gaming, watching sports, and fast action), which would have necessitated looking at more expensive 240 Hz active sets, but was able to stick with 120 Hz for passive.

The downgrades in quality I made: passive sets have a more strict angle of viewing, requiring viewers to be close to center. Not ideal for large viewing groups, or set-ups where the TV must be at an angle from the viewer. In addition, there is the 1080i vs. 1080p issue; I found the effect to not be noticeable. However, I did see a noticeable drop in resolution with the original 540p algorithm; if the firmware had not updated, I’d have gone with active. Not sure what methods Vizio or Samsung use on their passive sets.

[Siam_Sam]

@tim-n-va

Does anyone make 3D glasses that are comfortable over prescrition eyeglasses?

I don’t know if they’re commercially sold, but the one or two times the wife and I tried out 3D in the cinema, the 3D glasses fit comfortably over our pescription specs. So they are out there.

[Chronos]

There’s been some mention of screens that work without the need for glasses. These all work on the lenticular principle: There’s a ridged cover over the screen that throws the different images in different directions. You’ve probably played with toys that show a different image from different angles: This is the same idea, just made higher-quality. The advantage, of course, is that you don’t need any glasses. The disadvantage, though, is that you can’t move your head much, or you start seeing the right-eye image in your left eye, and/or vice versa.

[Student_Driver]

@Chronos

There’s been some mention of screens that work without the need for glasses. These all work on the lenticular principle: There’s a ridged cover over the screen that throws the different images in different directions. You’ve probably played with toys that show a different image from different angles: This is the same idea, just made higher-quality. The advantage, of course, is that you don’t need any glasses. The disadvantage, though, is that you can’t move your head much, or you start seeing the right-eye image in your left eye, and/or vice versa.

I imagined this would be the case. Restricted view angle is one of the downsides of passive sets that use glasses, and sounds like it’s going to be a downside of any passive set.

[Chipacabra]

@Chronos

There’s been some mention of screens that work without the need for glasses. These all work on the lenticular principle: There’s a ridged cover over the screen that throws the different images in different directions. You’ve probably played with toys that show a different image from different angles: This is the same idea, just made higher-quality. The advantage, of course, is that you don’t need any glasses. The disadvantage, though, is that you can’t move your head much, or you start seeing the right-eye image in your left eye, and/or vice versa.

This is how the nintendo 3DS works. Since it’s a handhold game console and, by its very nature only has one person viewing it at a time, it works really well.

Also, with the advent of head tracking, there are parallax tricks that you can do even with a traditional 2D screen that are very convincing. The human brain uses a bunch of visual cues to create a 3D image, and stereoscopic vision is only one of the tricks. On the other hand, head tracking doesn’t work very well with more than one viewer!