"Shrek 2" may pick up the storyline right where the first one left off - Shrek is back from his honeymoon and ready to face the dreaded in-law "meet" - but technically, the second story about the not-so-jolly green lug is a few giant steps beyond the first film.
"We made a conscious decision to get more complexity," says visual-effects supervisor Ken Bielenberg. The most important new tool in their "paint box," he says, is a more powerful computer. Mr. Bielenberg says the machines used to make "Shrek 2" are about five times the speed of those utilized on the first film - power critically important to producing a bigger vision. "We weren't happy with the level of detail in the first one, it looked too much like a manicured golf course," he says.
Sitting in front of a computer screen full of forest shots from the new film, Bielenberg points to all the lilting and shimmering greenery. Then he illustrates how the animators were able to grow more grass, paint three-dimensional vines on objects that could move in the wind, and have more "set dressing" - like leaves scattered all around.
The more powerful machines allowed the filmmakers to create individual programs that control each tiny area of the picture.
"There's a tree system, there's a foot dust system, a gravel system for when the donkey runs along," he says, adding with a laugh, "and there's a fur-shading system, which we also used for growing moss."
The film's three directors say the heightened computer power gave new life to familiar figures, an important boost for a sequel.
"We didn't want to just redo the earlier film," says Kelly Asbury. "It was important to give another level of reality," adds fellow director, Conrad Vernon.
He points to small but important details. In the first film, he says, Shrek had a very simple eye. "They painted eyes, put them on a ball, and popped them in his head," he says. This time around, the computers kicked in and gave the big guy eyes that would turn Frankenstein's monster a very Shrek-like green with envy.
"In this, they created a lens and pupil and iris, they actually re-created a human eye," says Mr. Vernon. "As a result, you get a much deeper connection."
Shrek's artists stress that the technology must always serve the artistic vision. Computer-generated effects are simply the tools of today's artists.
Artists have always been drawn to the latest technologies, says production designer Guillaume Aretos. "We are interested in it as a medium to express ourselves, just the way artists were with oil painting when it was first invented back in the 14th century."
All that said, the directors are also quick to point out that the film lives or dies on its story. "We'll keep raising the bar technologically because we can," says director and screenwriter Andrew Adamson, "but is all that essential to the storytelling? No, the story would work just as well without all the leaves in the forest or the individual hairs."
This is a sentiment the technical team is quick to support, if for no other reason than that the technology curve itself may be slowing down. Bielenberg points to the advance made between the Dreamworks film 1998 "Antz" and 2001's "Shrek." That film was 10 times the complexity of "Antz," whereas "Shrek 2" is only two to three times the complexity of "Shrek."
Now that additional Shrek sequels have been announced, director Adamson says he already has the plot evolution mapped out in his head. "The first 'Shrek' was about him learning to be lovable," he says. "The second is about how to love. The third will be about how to love himself."