The footage takes viewers to the planet Pandora, where an ex-Marine (Sam Worthington) is among a group of humans who have their brains linked to cloned versions of a native species in order to safely explore the spectacular environment. Sigourney Weaver plays a botanist overseeing the exploration. She, too, embodies an avatar based on the tall, lithe, tailed, blue humanoid species that populates the planet.
Together they meet an enormous hammerhead dinosaur with a plume of multicolored spikes on its face and the snarling tiger-like creature that scares it away.
Another scene shows Worthington's character befriending a native woman (Zoe Saldana). They discover a psychedelic forest of luminescent flowers and battle an army of flying dragons. Relying on 3D and performance-capture technology Cameron has helped pioneer, "Avatar" is an immersive blend of animation and live-action movie magic.
Fans at an IMAX screening in Los Angeles were overwhelmed by the 3D footage.
"It was almost a sensory overload," said Ryan Moore, 23, a student at Ohio State University. "You have to be in the moment wearing the (3D) glasses to really appreciate it."
Dwayne Smith of Venice was taken with the digital effects.
"It looked very real, especially the aliens. It looked amazingly real," said the 45-year-old. "It was one of the most amazing things I've ever seen, actually."
The free preview convinced one fan to buy a ticket on the spot.
"I think it's going to be one of the greatest movies this decade," said 21-year-old film student Derek Nunn.
The screenings, shown on some 440 screens in 58 countries, kept social networking sites abuzz with fan feedback.
One who was disappointed with the trailer said seeing the extended footage in 3D changed his mind about the movie.
"It is essential that you watch it in IMAX 3D, or 3D," Manoj Patel of Manchester, England, wrote on the film's Facebook page. "I just got back from watching the 15-minute footage, and I've got to say, my mouth was wide open all the way through."
Response to the film's 2D trailer, which debuted online Thursday, was mixed. Analyzing the two-minute teaser, several movie blogs
- including Movieline.com and Spout blog - noted the film's similar appearance to the 2008 animated flop "Delgo" and other science fiction movies.
