Water, water, everywhere — but how do you make it move?
That was the question for the creators of the family film Flushed Away, which tells the tale of a mouse at sea in a sewer.
"Initially, Plan A was to do it stop-frame, actually," said producer Peter Lord. He helped develop the Flushed Away story and is also the co-creator of Aardman Animation, best-known for its stop-motion Wallace and Gromit projects. "But then common sense kicked in and we thought, it's just not going to happen."
In that type of animation, the puppets, props and background elements are manipulated ever so slightly for each frame of a movie.
But there are only a few materials that mimic water in a stop-motion production, Lord said, including plastic food wrap, glycerin and K-Y Jelly.
And none of those options could work for scene after scene of the sloshing, swirling, rippling, splashing stuff that Roddy the mouse finds himself in when he's flushed down a toilet to a rat-ridden underground re-creation of London.
Lord says the team then considered using puppet characters against a computer-generated background. "But that was ridiculous, actually. That was like making two movies, which is an expensive option."
In the end, Flushed Away is a 100 percent CGI production created at DreamWorks Animation, with inspiration for its look rooted in Aardman's familiar puppet features (broad mouth, narrow teeth, expressive round eyes) and their clay-animation ways of moving.
"There was no question about disguising its Aardman ancestry," Lord said of the collaboration with DreamWorks' computer animators. "So that gave us carte blanche."
"They're so committed and completely giving," Aardman-based director Sam Fell agreed. "You don't need to worry too much about the technical side. You just sort of keep asking for what you want, and they keep giving it to you."
Roddy, voiced by Hugh Jackman, is leading a pampered pet's life in a posh Kensington apartment until a sewer rat invades his home and sends the city mouse down the drain into an adventure among common rodents. In his quest to get home, Roddy meets Rita (Kate Winslet), a street-wise (or canal-wise) rat with a rustic boat and a goal of her own.
"It's like The African Queen, only she's the one with the oily rag around her neck, and he's the guy who'd like a nice cup of tea," Lord said.
Meanwhile, a baddie known as the Toad (Ian McKellen) has various ill intentions — to get a jewel Rita found, which could save her family from poverty, and to wipe out the sewer system's rat population so he can reign supreme. Doing the Toad's dirty work for him is a pair of not-too-bright rats, Spike (Andy Serkis) and Whitey (Bill Nighy).
To do his first animated voice role, Serkis sometimes alternated his DreamWorks recording sessions with his motion-capture work in Peter Jackson's King Kong, giving life to the giant ape. "I was 25-foot-8 (8.7m) by day and a 6-inch (15cm) rat by night," he said.
Serkis said he was drawn to Flushed Away by his longtime admiration for Aardman's Oscar-winning films as well as its knack for bringing out the reality in sometimes outrageous characters.
"I just think the world they've created is so rich, and that whole sewer version of London is such a great world," he said. "There isn't a frame where there isn't a hundred things going on.