Seven factors that could trip up the industry's 3-D push

First problem: subtitles on 3-D content.

How to deal with subtitles, or more importantly closed caption information which is mandatory in the United States, on a 3-D TV remains an unresolved issue. One can put a subtitle on a 3-D film, but when an image jumps off the screen, the subtitle follows. "It all depends on depth of a screen for now, we don't have a definitive solution," acknowledged Panasonic's Kozuka.

Second, sports and live events broadcast in 3-D.

No videographers and producers have enough experience with shooting live events in 3-D.

In a live 3-D baseball game, for example, cameras would have to be relocated from long-familiar 2-D vantage points in order to follow the flight of a 95-mph fastball from pitcher to batter, and again from batter to wherever the ball lands. In a football game, a long pass might be impossible to capture in a single panning shot with one 3-D camera. But if a camera switch is necessary, the whole play could be lost in transition.

Third, animation in 3-D is fine, but what about others?

So far, Hollywood studios have been able to demonstrate the effective use of 3-D in animation films. "But animation is after all depicting a fantasy world," said Reiji Asakura, an author and audio/video critic in Japan, who moderated the panel.

The real test is in a regular film, shooting the real world. "Even a slight discrepancy shown in 3-D will turn the audience off, because we all have a real-life 3-D experience," he noted.

Fourth, what about those cockamamie glasses?

Whether using active shutter glasses or polarizer glasses, the question is: "Will consumers be asked to wear them all the time?" asked one of the attendees. The inconvenience factor would be substantial. "Most people today watch TV while doing something else -- whether eating supper or reading a newspaper," he pointed out.

Fifth, how much is it?

No vendors have disclosed how much a new 3-D Blu-ray player or a 3-D TV set will cost -- yet. At a time when the global economy remains weak, it's unclear who's ready to jump on the newest gadget, except perhaps for the gadget-happy consumers of Japan.

Sixth, did you say "3-D PC?"

In different parts of the world, PCs continue to gain momentum as a primary device for entertainment. Sony says it has a plan for 3-D Vaio PCs, but the company offers no details on how to enable a PC with 3-D.

Seventh, is 3-D safe for your eyes?

The biggest question mark, and a potential deal breaker for 3-D, is -- no kidding -- optical safety. There is not enough evidence to determine whether watching 3-D intensely on a game console for hours is harmless. Vendors claim they will be taking precautions and working on guidelines. But the safety issue, if mishandled, could send 3-D back to the same drawing board where it died in 1954.