While the blue-skinned Na'vi are shooting arrows out of the screen toward the audience in the 3-D movie “;Avatar,”; another battle is being fought in the theater—over the goofy-looking glasses that moviegoers must wear to see the three-dimensional effects.

Four companies are fighting for bridge of the nose with three different technologies. Each of them is more advanced than the paper glasses worn to view “;Bwana Devil,”; regarded as the first of the commercial 3-D movies in the 1950s, but all work on the same general principle. Each eye sees a slightly different frame of the movie, but the brain puts them together and perceives depth.

About 4 million glasses made by RealD, the market leader, were worn during Avatar's opening weekend in the United States. RealD's glasses use polarized lenses and cost about 65 cents each. MasterImage 3D, another vendor, uses a similar technology.

Dolby Laboratories, the company behind theater sound systems, makes glasses that filter out different frequencies of red, green and blue. They cost about $28 each. The glasses of the third company, XpanD, use battery-powered LCD shutters that open and shut so each eye sees the appropriate frame of the movie. Those cost as much as $50 each.

Each company claims its glasses and projection-system technology is better. Because glasses using one technology are useless in a theater using a different digital projection system, the companies backing the three technologies are battling for the upper hand while the 3-D industry is still in its infancy.

James Cameron, the director of “;Avatar,”; is more often than not the main marketing tool. He has endorsed RealD, says the company, which has about 5,000 screens using its system. But he, his wife and his production partner were photographed at the premiere in Japan wearing XpanD glasses, which work on 2,000 screens worldwide. Dolby says its glasses work with 2,200 screens, but it has no Cameron connection. The company helpfully points out instead how a malfunction in the RealD system spoiled a press preview of “;Avatar.”;

The battle over what glasses patrons wear is a big deal because exhibitors are convinced that 3-D, while seeming like a gimmick now, will lure movie lovers away from their crisp high-definition widescreen TVs at home and back to the theater. Maria Costeira, the chief executive of XpanD, believes the sky's the limit: “;Eventually, we'll see 3-D movies on airplanes as well.”;

The fight over the glasses may well intensify because TV makers are pushing 3-D TVs for the home as a way to increase their sales of more expensive sets.

Despite the marketing, when it comes down to choosing a 3-D system, many exhibitors are making a decision based on one factor: Do they want to be in the cleaning as well as the movie business?

The expensive Dolby and XpanD glasses go into a dishwasher after each use, not the trash. Both companies recommend that theater owners clean them in an industrial-grade machine. (To prevent pilfering, Dolby and XpanD glasses can also contain built-in antitheft tags that can be activated by exit-door sensors.)

XpanD offers its theater partners disposable wipes that it can distribute to customers along with their tickets to assure them the glasses are germ-free.

RealD, whose cheap throwaway glasses were being perceived as a liability, has addressed concerns of hygiene. Theater owners are encouraged to ship back the used glasses to the company, which will clean, repair and repackage them for other theaters.

But in all the hubbub about each product's advantages and which system Cameron really, truly loves, the most important question remains unanswered: Does one system create a better looking 3-D picture than another?

“;I don't think the consumer can tell the difference,”; said Joe Miraglia, the director of design, construction, and facilities for ArcLight Cinemas, a chain of luxury theaters based in Hollywood. The movie chain uses each system in one or more of its theaters, and finds the cost of operation to be roughly the same for all.

While Miraglia uses RealD in several theaters, he chose XpanD's LCD glasses for the large curved screen in the company's flagship Cinerama Dome theater on Sunset Boulevard. This is similar to the technology that will be used by Panasonic, Sony and others as they bring 3-D HDTV to market next year. Recently, electronics makers set standards for creating 3-D Blu-ray discs and players.

But in order to make the wearing of 3-D glasses as routine as ordering popcorn, the makers need some help in the design department. Many of the glasses resemble the “;fitover,”; or wraparound sunglasses favored by senior citizens in the Sun Belt, a look that is not appealing to young moviegoers.

RealD and XpanD hope that 3-D will soon become a fashion statement. In addition to its standard movie glasses, RealD is introducing child-size versions, as well as high-style 3-D specs that people can wear without embarrassment out in the three-dimensional world as sunglasses or prescription lenses.

Costeira of XpanD thinks personalized designs that can be used with 3-D HDTVs and video games could turn into something big. “;Stylish, thin and light, 3-D glasses will become your new iPod,”; she said.