Known as a genius for the way he seamlessly combines technology and storyline, Cameron is alert to the epic's emotional appeal.

The hero Jake Sully, an Avatar played by Sam Worthington, falls in love with Neytiri, a Na'vi princess played by Zoe Saldana. Their emotional bond, as Cameron elaborates, is at the center of the film.

"I learned the lesson on 'The Terminator 2' that if a movie doesn't have heart, doesn't make you feel the emotion, it has no purpose," he says.

"The film is a little bit overwhelming from a technical stand point, but I think the audience cares more about what they see on the screen, they care about the people, the relationship."

In "Titanic," Cameron found the balance between technology and emotion was one of the biggest challenges for a filmmaker. Fortunately he made it, by putting the visual effects, giant sets and thousands of actors, in balance with small intimate moments, to make the film really resonate for the audience.

"You will see the same balance and blend in 'Avatar,'" he promises. "It costs a million dollars a minute to do computer-generated characters in 'Avatar', so it's a very difficult thing to stop for those extra few seconds, the extra bit of time to let the characters have an intimate moment together, maybe just a look, a glimpse, or just a line of dialogue, but you have to do it, that's really critical."

In a time when blockbusters need to be "pre-sold", by comic books (Batman), bestsellers (Harry Potter) or toys (Transformers), "Avatar" does not have these advantages and is a brand new thing to audiences, globally and in China alike. Yet Cameron, who proclaimed, "I am the king of the world", at the 1998 Academy Award ceremony, which he swept with 11 wins, sees it as a legitimate concern.

"It is not a limitation that I ever believed in because 'Titanic' was not pre-sold, 'True Lies' was not pre-sold, and when I made the first 'Terminator' film, nobody ever heard of that," he says.

"I don't think Hollywood should accept that limitation, Hollywood should have the courage to make films. I am sure in the Chinese film industry you have the same issue. People need to have the courage to make new things, even at a blockbuster level of budget."

Blockbusters with a mega budget have become a norm for Cameron. The 55-year-old earned a record $1.8 billion globally for "Titanic," which cost $200 million, at the time the most expensive film ever made. When he made "The Abyss" in 1989, it was also dubbed the most expensive movie ever made, though that was not true. "The Terminator 2" was also the most expensive movie made, at the time.

"I do like to make big, expensive and visually spectacular films," he says. "I think the way people should look at this is, you spend the same amount for a ticket, no matter what the movie costs. So if a film costs more and brings more pleasure, more visual enjoyment, more spectacle, that's the best entertainment bargain you can get. As long as my films make money, people should feel good about what they cost."

The film is expected for a theatrical release on Dec 18 in North America and around Jan 2 in China, in both 2-D and 3-D.