MPC was responsible for the creation of a huge menagerie, including Asterius, the minotaur. Some creatures were full CG creations, others were a combination of live-action and CG body extensions.

The Return of Aslan
Meanwhile, at Framestore, VFX Supervisor Jon Thum and his team were busy tackling their own set of creatures, including the star of them all, Aslan. Voiced by Liam Neeson, the majestic god-like lion had been created -- successfully -- by Rhythm & Hues in the first movie. For the second movie, the team set out to make it look even better. Having recently created polar bears for The Golden Compass, Framestore had the perfect set of grooming tools to develop Aslan's mane. After months of development, the character was able to sport the most complex fur groom ever created at the studio.

Aslan's animation proved to be just as challenging, as the character's position in Narnia led to a specific behavior. "We tried not to over-animate him," Rogers observes. "He didn't need to move a lot to express his power, and we had to convey that by producing a subtle, even subdued performance, which is always difficult for animators. We spent a lot of time working on muscle structures and wrinkle placement to display emotions ideally. In one scene, Aslan is in full close-up and listens to what Lucy is telling him. The animators had to convey all his thoughts with minimal dialogue."

One of the aspects of Aslan that the team really wanted to improve on was his physicality. "We worked really hard to make him look and feel real," Wright says. "There is a scene in which young Lucy Pevensie hugs him and they both roll around playfully. We had to create a realistic interaction between Lucy's arms and Aslan's mane, which required a tremendous amount of work. First, we shot the plate with actress Georgie Henley hugging Shane Rangi wearing a fake Aslan head and torso -- we always filmed our 'stuffie' (KNB created a fantastic Aslan head with fake fur) as a lighting reference for every Aslan shot. Then, Framestore painstakingly removed Shane from the shots, and replaced him with the digital Aslan. A CG Lucy double was then animated to match the arms and head movements of the real actress. They were used as dynamics objects to generate realistic collisions with the CG mane, but the final composites feature the real arms and head. It was painstaking and complex work, but it really helped the character feel physically present in the scene."

Besides Aslan, Framestore also handled another key character, Trufflehunter. Since the badger is a newcomer in the Narnia saga, the team had to design and build it from scratch. Trufflehunter is considered by Narnians as the voice of wisdom, a character who remembers the old ways of their world. He had to deliver a lot of dialogue, but also feature typical badger behavior, notably when sniffing the air around him. Just like MPC with Reepicheep, Framestore's animation team worked hard to develop an animation style that would convey the character's acumen, while retaining his animal quality.

Framestore handled another key character, Trufflehunter, a newcomer in the Narnia saga. The animation team worked hard to develop an animation style that would convey the character's acumen, while retaining his animal quality.

Animating a Fluid Simulation
One of Prince Caspian's toughest animated technical challenges was tackled by ScanlineVFX, a German company (with a new L.A.-based office) that had recently garnered a lot of attention in the industry with its groundbreaking fluid simulation engine Flowline. "They had to create the River God, a giant character that is made out of the water of a river," Rogers says. "It constantly sucks water in a vortex motion from the river, spiraling up inside the body and pouring down again as his arms and hair. The character appears in only 22 shots, but they were all extremely complicated, as the team had to combine character animation and fluid simulation. And there's only so much that you can do to control a natural phenomenon before it no longer looks natural at all…"

To bring the River God to life, Scanline and VFX Supervisor Stephan Trojansky developed a system that allowed the artists to create directable fluid simulations within Flowline. It had to be a closed system where no single drop of water would disappear or could be cheated away.

The team developed a pipeline that based all simulation setups on a keyframe animatable polygon-character rig. Flowline was extended with features that allowed a realistic flow of the water with foam, splashes and bubbles, while following the keyframed motion of the character. One of the core features of Flowline is to allow rendering of all its simulation data in one beauty pass, including water, spray, bubbles, foam, self shadowing, global illumination and caustics. Indeed, the River God was created with just one beauty pass and some adjustment layers for the compositors to fine-tune the shots.

With all of its unique challenges, Rogers and Wright believe that Prince Caspian's visual effects succeed in surpassing the accomplishments of the first movie. "The second movie is definitely bigger, and I'm really proud with the work that was done," Wright concludes. "Most of the time, the vendors have actually exceeded our expectations. With Andrew's inspirational directions, they all did a fantastic job."

Alain Bielik is the founder and editor of renowned effects magazine S.F.X, published in France since 1991. He also contributes to various French publications, both print and online, and occasionally to Cinefex. In 2004, he organized a major special effects exhibition at the Musée International de la Miniature in Lyon, France.