It only takes one surprisingly successful film to spark a new Hollywood trend. For instance, the breakout 2009 hit The Hangover paved the way for the eight R-rated comedies that were released this summer. The unparalleled grosses of Avatar motivated studios to start shooting everything in 3-D — or at least convert their films to the third dimension after the fact. And now, thanks to the unexpected box-office dominance of Disney’s The Lion King 3D, we may have a new craze to anticipate and/or fear: the 3-D rerelease.

In just 10 days, The Lion King 3D has earned $61.5 million, topping the box office two weekends in a row and exceeding Disney’s wildest hopes for the 17-year-old movie. “There has been very low success with rereleases historically,” says Dave Hollis, Disney’s executive VP of theatrical exhibition sales and distribution. “Originally, we thought [The Lion King 3D] would do somewhere in the low-to-mid teens its first weekend.”

Instead, the 3-D rerelease wound up debuting to $30.2 million — the fourth-best September opening ever. As a result, Disney will be extending Simba’s stay in theaters past the studio’s originally intended two-week engagement, even though the film is being released on Blu-ray next Tuesday.

When The Lion King 3D‘s massive numbers came in, you could practically hear Tinseltown’sstudio executives collectively exclaim, “Aha!” Stereoscopic conversions were already in progress for Star Wars: Episode I — The Phantom Menace and Titanic, which will be released next year on Feb. 10 and April 6, respectively. (A 3-D version of Top Gun is also expected to hit theaters in 2012, but Paramount hasn’t announced a release date yet.) But these films could be just the beginning of an avalanche of 3-D reissues. “They see the potential,” Avatar director James Cameron recently told the Los Angeles Times. “All it takes is a little healthy greed.”

But before we start building an underground shelter to protect ourselves against the possible threat that is My Big Fat Greek Wedding 3-D, let’s give Hollywood a chance. As I spoke to a number of industry insiders about the future of 3-D reissues, a set of rules started to emerge regarding which films should be rereleased in 3-D and how. It was encouraging to hear that, at least at this juncture, there is an understanding that only a select few motion pictures deserve The Lion King 3D treatment.

Here are those rules for 3-D rereleases. Hollywood, you shall not disobey:

1. Pick only the crème de la crème of beloved blockbusters.

There are hundreds of box-office hits that Hollywood can choose from for a 3-D rerelease, but studios should be picky. “There is a judiciousness that needs to be applied to carefully selecting films that transcend time, that appeal broadly across generations, and that will be meaningful again in a new format,” says Hollis. “From our perspective, there are not many films that are going to satisfy all the prerequisites.” The Lion King, however, was the rare movie that did.

2. Get the original filmmakers involved.

Don Hahn, who produced The Lion King back in 1994, oversaw its 3-D conversion and consulted with the film’s directors, Roger Allers and Rob Minkoff. If the original filmmakers refuse to participate or are no longer around, then you may be better off leaving the film alone. “I don’t think you want to convert some classic title like Citizen Kane,” says Rob Hummel, president of the 3-D conversion company Legend3D. “You don’t know what Orson Welles’ intent was in certain scenes.”

3. Wait until there’s a new generation of moviegoers to experience the film.

Enough time had passed since The Lion King‘s original release that those who initially saw the film as a child were now old enough to take their own children to seethe 3-D reissue. And those who were parents when the movie first came out may now have grandchildren. Rereleases provide one generation the opportunity to share its nostalgic memories with the next generation. But this “circle of life” will only work if the studios remain patient.

4. No quickie conversions.

“If you go compromising the process, you damage the business for everyone,” says Hummel. The Legend3D president estimates that a 110-minute film can be converted from 2-D to 3-D for about $3 million or $4 million. The cost has fallen as the company’s software has rapidly improved — that price tag would have approached $10 million a year ago. And then you have a perfectionist like James Cameron, who convinced Fox and Paramount to spend $18 million to convert Titanic over the course of a year.

5. Give the movie the marketing campaign it deserves.

After the painstaking process of converting some classic film to 3-D, don’t get cold feet when it’s time to release the picture. Assuming you picked a movie worthy of being rereleased, you should advertise it as the big tent-pole that it is. “Disney marketed The Lion King 3D as if it were a completely new release, which is what you need to do,” says a Hollywood executive who opted to remain anonymous.

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