The dragon posed a design challenge, particularly around its face, to subtly connect with the actor and to also create the feeling that it was a youthful dragon that could play emotional moments when he's more vulnerable and less defensive. "It's tricky having believable characters that need to be expressive, so it's that melding of human facial features with different animal morphologies," Valdez continues. "And with the dragon there was concern about how the skin would look and we went ultimately for a crocodile hide feel. That challenged us in the skinning area because we wanted the skin to stretch but when it compresses to fold and buckle. We have a combination here of muscle and skin simulation tools plus good old-fashioned sculpting for a layered approach. His wings too were difficult to make look natural."

The trick with the sea serpent was that he had a complex rig and had to wrap himself around the ship. "At one point, he opened his body to reveal all these horrifying inspectoid spines," Valdez explains. "This horrified the animators when they first started because there were so many limbs to articulate, but they ended up being a combination of procedural wavelet motions with keyframes. And we did a big motion capture shoot for a crowd library of sailors on the ship. There are a few dozen shots of a full-CG boat and the full-CG crew on the deck and that was pretty easy work for our Alice crowd tool."

A more abstract challenge was how to depict the amorphous Dark Island, which represents the force of evil in Narnia. "We did various experiments with particle and fluid simulations and created an island-sized massive cloud that has an almost octopus form with large tendrils that reach out into the ocean," Valdez suggests. "The trick was to have parts of the smoke contracting and to have the tendrils squirming and twisting to keep the smoke bound to this shape. That took a few months to figure and a lot of rendering development to figure out how to render the complex simulation of millions of particles with internal light as well as external soft shadowing from the sun. It's not quite a character but is a definite presence and connects with work done at Cinesite with the smoke tendrils that appear in other scenes throughout the film. The final battle takes place inside the creature, which required a separate effort throughout the last 200 shots done on bluescreen stages where an entire mood and look had to be established and a certain grade had to be figured out. We used quite a lot of Nuke for that."

For its part, Cinesite, under the supervision of Matt Johnson, provided CG particle mist tendrils that were extensively featured in the early part of this "Figures in the Mist" sequence with 60 shots. These ghostly trails were created in Houdini utilizing bespoke fluid simulation tools.

Animations were blocked out for each tendril shot using "character" eels to give a sense of position, speed and movement to the mist. The animations were cached, and fluid simulations derived from the data. Houdini renders produced numerous lighting passes for each of the mist tendrils. These included passes for light emitting particles, internal beams and shadows, all of which could be controlled in Nuke to achieve a desired look per shot.