Why Eyewear-Free 3DTVs Are Hard to Build

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One of the questions that always (always) comes up in discussions about 3D television is this: “Will there ever be a 3D TV that doesn’t require the glasses?”

Regardless of your stance on the matter of whether and why people are put off by 3D-TV eyewear, it’s a valid question. Dedicated eyewear for television watching seems destined to parallel the fate of the TV remote: Something that gets sat on, chewed on, spilled on and lost in the cushions. Sometimes simultaneously.

Many of us have seen 3D televisions that don’t require special eyewear. Visually, most of us have the same reaction: Eh, maybe not; a little off; needs more work.

From a usability perspective, it’s worse: Forget about lying down or tilting your head or even moving, in some cases. Today’s auto-stereoscopic 3D TVs require the viewer to stay in a fairly fixed position.

Ever wonder why? I did, and was glad to learn more about it during a standing-room-only technical session at last week’s Cable Show in Los Angeles.

Here’s why doing 3D without the glasses is so hard: It needs more (many more) than the two camera angles (one for each eye). And, each extra camera “view” divides the resolution.

That’s not to say it can’t be done, but, it’s going to make for a really, really large video stream, relative to today’s high-definition TV streams - which are already pretty large, compared to standard-definition TV.

Mark Schubin, a 3D expert and operator of SchubinCafe.com, described an NHK display of glasses-free 3D he saw at the 2009 NAB show: “It was spectacular. You could move your head in any direction; you could look around objects - but the quality was less resolution than YouTube.”

Plus, he said, the footage was shot using an 8K camera - meaning 16 times the pixels of an HD camera. So, to get to really good auto-stereoscopic television, “you may need 100 times the picture information” of HD, he explained. For mediocre quality, it’s still a video stream that’s five or more times larger than an HD stream.

That’s why glasses-free 3D may emerge first on smaller, personal devices, noted David Broberg, vice president of consumer video technology for CableLabs, who also spoke on the panel. With the use of a method called “parallax barrier,” the sweet spot for 3D viewing is technically and visually manageable on a smaller screen.

So, the answer to the question of whether there will ever be glasses-free 3D TV is yes - and no. Surely, someday. But probably not anytime soon, especially when it comes to big-screen TVs.

Until then, the 3D glasses become another thing to keep away from the puppy, the beverage and the couch cushions.

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