Hollywood's faith in the power of 3D movies to deliver a bright future of packed cinemas and spectacle-wearing audiences has been jolted by figures that show the format may already be floundering.
Seven months ago, James Cameron's science fiction epic Avatar burst on to the screen in three dimensions, taking in US$2.7 billion ($3.71 billion) and becoming the world's highest-grossing film.
Studio executives compared the breakthrough with the development of the first ''talkies'' almost a century ago, and fell over one another in the stampede to produce more such films.
But with the tally of major films released in the new format expected to reach 22 by the end of the year, there are signs that 3D may not, after all, be the panacea for falling ticket sales.
The proportion of cinemagoers who opt to see new films in their 3D versions has fallen steadily over recent months, with more opting instead to watch them in the traditional - and cheaper - formats.
When Avatar came out in December, 71 per cent of Americans who went to see it on the opening weekend opted for a cinema showing the 3D version.
In March, when the animated fantasy How to Train Your Dragon was released, 68 per cent of the audience chose to see the film that way.
But by May that figure for Shrek Forever After was down to 61 per cent. At the beginning of this month only 56 per cent saw The Last Airbender in 3D, and a week later the proportion fell even lower, to 45 per cent, for the newly released animation Despicable Me.
The figures have provoked an anxious debate within the film industry, which had previously hatched plans to convert popular films on its backlist into the cinematic style du jour.
Studios are already working on at least 24 new films in the expensive format for release next year. Some fear that the ''3D bubble'' has already burst.
Critics say part of the problem may be the technology itself. While Avatar was made specifically in the new format, studios have hurriedly converted films that were originally made for two dimensions.
The process can cost up to US$100,000 a minute of film but can be done in a matter of weeks, allowing for a quick release. But for much of the time it simply doesn't work and delivers murky pictures.
After seeing director M Night Shyamalan's summer blockbuster The Last Airbender, starring British actor Dev Patel, the influential US film critic Roger Ebert said it ''looked like it was filmed with a dirty sheet over the lens''.
He said Hollywood's current infatuation with 3D was just an excuse to add surcharges to already expensive cinema tickets. ''3D is a waste of a perfectly good dimension and Hollywood's current crazy stampede towards it is suicidal,'' Ebert said.
- The Age