"We had gigantic challenges along the way. The battle alone was made up of thousands and thousands of creatures, which includes polar bears, lions, tigers, centaurs, ogres, boggles, etc. Just an incredible undertaking."Producer Mark JohnsonThe creation of Narnia would ultimately require more than just creative power - it also required massive computing power, combining the efforts of the some of the hottest and most innovative effects houses in the world to digitally enhance the otherworldly characters and landscapes of this alternate universe. "This is a story filled with incredible creatures," remarks Adamson. "To give a sense of the scope, in the final battle, there are 20,000 creatures. All these creatures were created at least partly in a computer but no singular approach was used. Some creatures are CG all of the time. Some creatures are half computer-generated and half live-action. A centaur, for instance, might have a human upper body with a computer generated horse lower body, while the beavers were entirely computer generated. The idea was to have it all meld together into one cohesive universe that feels entirely real." "The Lion, the Witch and the Wardrobe" is one of the biggest special effects movies ever made," adds producer Mark Johnson, "and to pull it off we used three of the biggest, most creative effects companies in the world - Rhythm & Hues, Sony Pictures Imageworks and ILM - simultaneously." In the beginning, the filmmakers asked several effects companies to "audition" for the various characters, almost like actors. Johnson explains: "We would take a single character, let's say Mr. Beaver, and ask five separate companies to take a stab at animating this character. There were no guidelines. We said `let's see what you can do to demonstrate what Mr. Beaver would look like.' That's how we chose the best houses for the job." Overseeing the work was VFX Supervisor Dean Wright, a veteran of the second and third "Lord of the Rings" films. Wright collaborated with Rhythm & Hues Bill Westenhofer, Sony's Jim Berney and ILM's Scott Farrar to create somewhere between 1,000 and 1,400 CGI shots and images for the film. According to director Adamson, "There really isn't one frame, one scene, that is not touched by a visual effect." Eventually, some 1,000 people would work on the effects and some 50 terabytes of information for the film would be stored at three different effects houses. Large libraries of newly created images were shared back and forth by each of the houses as they worked in concert with one another, layering scenes with richer and richer effects. So while Sony Pictures Imageworks was creating the CGI beaver performances and forging CGI wolves so photo-realistic they were able to mix seamlessly in with a pack of real animals in certain sequences, Rhythm & Hues was honing Aslan's magnificent musculature and ILM was tinkering with how centaurs might walk. Then, the teams might switch, each working on a different aspect of Narnia's massive world. "In every element, the aim was always to have each the creatures be entirely believable right next to our human cast," sums up Wright.Ultimately, all the film's elements - from locations and designs to practical effects and digital wizardry would come together in the most challenging sequence of all: the climactic battle for Narnia as Aslan's army takes on the forces of the White Witch. Andrew Adamson had envisioned a spectacular scene involving some 20,000 characters on screen at once - one that sprung primarily from his imagination. "In the book, the battle is one about a page and half long. Lewis writes about it in very simple, `you should have been there' terms, but in my imagination was always this incredible battle with minotaurs against centaurs against fauns and satyrs. We had to show the battle, an incredible battle like nothing that has ever been done before," says the director. The sequence was shot at New Zealand's Flock Hill Station, on a rugged plateau featuring snow-capped vistas. There, the film's cast and hundreds of extras dressed in the otherworldly creations of WETA and K.N.B., played out the war for Narnia's future. Later, Rhythm & Hues employed the same groundbreaking software used to create the spectacular battles in "Lord of the Rings' - the artificial intelligence program known as Massive - to multiply the fighters into the tens of thousands and to control each fighter's individual moves and motions. "We have 20-30 creatures on screen at any one time and they each have their own unique attributes in terms of how they jump, run, walk, move and fight," observes Dean Wright. "It's an enormous challenge to make this look believable, but with the computer simulations, you have the tools you need to make it look as good as it possibly can." When the battle was completed, Andrew Adamson knew his Narnia had truly made the journey from a fantastical vision in a child's fevered imagination to the motion picture screen. "Making this film was a daunting exercise in every way," sums up Adamson.