ESPN producer Phil Orlins shows a 3-D camera setup.

LOS ANGELES — Phil Orlins knows everything about producing TV in three dimensions including greens of Augusta National and the flying motor bikes of the X Games for ESPN's 3-D channel. But he can only guess how well his shows resonate with viewers. That's because 3-D audiences are so small they can't be measured by Nielsen's rating system.

Orlins' problem is that fewer than 115,000 American homes are tuned into 3-D channels at any one time. That's less than one-one hundredth of the 20.2 million-strong audience that saw television's highest-rated show, NCIS, this week.

ESPN 3D is one of nine 3-D channels that launched in the years following the late 2009 release of James Cameron's Avatar. Enthusiastic television executives expected Avatar to spur 3-D's transition to American living rooms, boosting sales of TVs and, they hoped, getting people to pay for 3-D channels.

That hasn't happened.

Only 2 percent of TVs in the U.S. are able to show 3-D programming which is about 6.9 million sets out of 331 million. After this year's Christmas buying rush, it is expected the number of 3-D-capable televisions in homes to jump to 19.3 million. Even so, 3-D TVs will amount to fewer than 6 percent of all sets.

At movie theaters, 3-D has attracted lots of viewers. But not at home. There's a supply problem: 3-D TV is expensive to produce, so there's not a lot of it. Of the content out there, some isn't very good. There's an equipment problem: Some people find the special glasses required for 3-D TV uncomfortable. And there's a money problem: Many wonder if it's worth the extra cost.

There's very little direct consumer demand" for 3-D, said Tom Morrod, a TV technology analyst with IHS in London. "They don't see a value with it. Consumers associate value right now with screen size and very few other features."

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Who’s watching? 3-D TV is no hit with viewers