Photo: The Canadian Press. All rights reserved.

In this Wednesday, June 27, 2012 photo, 3-D TV operator Cody Miles adjusts camera focusing settings for a 3-D production for ESPN 3-D Network at the ESPN X-Games at the Staples Center in Los Angeles. (AP Photo/Damian Dovarganes)

Phil Orlins knows everything about producing TV in three dimensions.

The ESPN producer has captured the undulating 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.

"The feedback on The Masters was fast and furious. You could go on Twitter at any moment, and there'd be comments coming in every minute about 3-D coverage," said Orlins while giving a tour of a production truck at this summer's X-Games. "But then you go to some other events where it's pretty quiet."

Orlins' problem is that fewer than 115,000 American homes are tuned into 3-D channels at any one time.

That's less than a hundredth of the 20.2 million-strong audience that saw television's highest-rated show, "NCIS," this week. 3-D viewership is so tiny that The Nielsen Co.'s methods are unable to capture any meaningful data about viewers' programming preferences.

ESPN 3D is one of nine 3-D channels that launched in the years following the late 2009 release of James Cameron's "Avatar." The 3-D blockbuster won three Oscars and ranks as the highest-grossing film of all time, garnering $2.8 billion at the global box office.

"Avatar" was supposed to change everything. Enthusiastic television executives expected the movie 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 never happened.

Only 2 per cent of TVs in the U.S. are able to show 3-D programming, according to the most recent data from research firm IHS Screen Digest.

That's about 6.9 million sets out of 331 million. After this year's Christmas buying rush, IHS expects the number of 3-D-capable televisions in homes to jump to 19.3 million, mostly because many new larger TVs automatically include the technology. If you're in the market for a big-screen TV, you're likely to wind up with 3-D, too. Even so, 3-D TVs will amount to fewer than 6 per cent of all sets.

"We've learned with every passing day that we were ahead of the curve further than we thought we were," said Bryan Burns, the business leader for ESPN 3D. "We hit the on-ramp earlier than we realized at the time."

At movie theatres, 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.