HDTV Almanac - Universal 3D Glasses

[alfredpoor]

One of the complaints about 3DTV that is often repeated in the press is that “there are no standards“. I may be the only one who does not see that as a major obstacle. After all, there are a lot of different digital image file formats out there, yet programs like Microsoft Word or most [...]

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[stevekaden]

Just kidding...though I'd expect that feature sooner or later (and then 'electronic skins').

Better of course would be a universal transmission standard. I mean how hard could it be to send a single switch pulse out?!

You have to give kudos to XpanD in not only have a good product already, but to have seen the market hole and jumping in immediately.

++ I have worn their glasses and find them quite comfortable, with a big field of view.

[mstockfisch]

CEA's R4 WG16 "3D Technologies" workgroup is in the process of standardizing the emitter-to-eyewear IR subsystem. The goal is to standardize parameters & signal protocol, with careful consideration given to interference from the environment and to other consumer products.

[hharris4earthlink]

This seems to be an electronic standardization of the link between the TV's emitter and the eyeglasses. Is there a psychological/perception standard that maximizes the viewer experience and minimizes eye strain, and if so, are TV manufactures following it? Having an electronic standard is all well and good, but I would think there must be a higher perceptual standard that the link standard must address.

[alfredpoor]

Perception is a slippery conception. It varies with individuals, and in macro/micro scales. There are no standards that I know of that set standards for stereoscopic imaging. It's not like light intensity -- such as lasers -- where you can set limits to prevent permanent vision damage.

It is generally accepted that 30 frames per second (fps) is sufficient for people to see smooth motion. (Movies are filmed at 24 fps.) 60 fps is typically required to eliminate any flicker. As a result, stereoscopic TV is run at 120 fps so that each eye gets 60 fps images.

The difference between the different sets is how the sync signal is encoded so that the glasses present the correct image for each eye with minimum crosstalk. But as for there being a "higher perceptual standard, I'm not aware of one.

Alfred

[hharris4earthlink]

Thanks. I have a feeling there's something missing here, probably my lack of knowledge of how this works. When we talk about normal film, we are talking about an image being replaced a certain number of times each time interval. In 3D glasses are the left and right picture replaced simultaneously? This would mean, obviously, that a 3D camera records left and right view simultaneously. But I had the impression that left and right are recorded one after the other and that 3D glasses continuously switch between left and right, using persistence of vision to allow the brain to integrate it into 3D.

[alfredpoor]

It's not exactly persistance that merges the left and right images; it's more like the fact that the images come quickly enough for the brain to perceive them as a single image; this is much like the red, green, and blue images of a DLP projector being merged in the brain to create a full color image.

The left and right images are presented sequentially, so each eye receives an image in turn. However, the frequency of the images to each eye is the same or faster than film or video. The home 3D systems use 120 Hz refresh rates, which means that each eye will see 60 distinct frames per second.

So, yes, the image "jumps" back and forth between the left and right eyes, but it happens so fast that it is perceived as smooth motion, just as with standard 2D video images.

Does that help?

Alfred

[hharris4earthlink]

Fascinating. So I assume the function of the glasses is to shutter out the left eye when the right image is being shown and vice versa. Is there an industry standard now so different manufacturers glasses will work with any 3D TV? Can 3D glasses be made light enough so they can be comfortably worn for hours at a time?

Looking into the future, for those of us who wear glasses anyway, would it be possible to wear prescription glasses that become 3D glasses when they receive a 3D signal? (Double as sun glasses?) Further into the future, how about contact lenses? Sounds like a growth market in innovation.

Thanks!

[alfredpoor]

Yes, the glasses close off the light to one eye then the other. They are typically called shutter glasses or active glasses. One of the major manufacturers of these glasses has a model that they claim works with all the major 3DTV models. (I have not tested this claim, but I have no reason to think it's not accurate.)

Yes, the glasses can be lightweight. I envision one possible future where most people will wear them all the time, whether or not they need corrective lenses. These glasses could serve as your Bluetooth headset, MP3 player, sunglasses, and more (as well as provide vision correction if needed), and use a combination of photovoltaics and energy scavenging/harvesting so that they would never need to be recharged.

Alfred

[hharris4earthlink]

Might even be a fashion statement and would save me running around like a dork with headphones and an iPod clipped to my belt. Very cool. I want one.