6'1" actor John Michael Higgins had been cast as 4' lead elf Willy, providing MPC with an interesting challenge. Split screens were used in the majority of shots in which Higgins interacted with lead actor Vince Vaughn.

"Each elf was built so that it could have its jacket on or off, wear ice skates or shoes and wear one of three pairs of glasses or not," Hormann notes. "To expedite the processing of the motion capture data, we came up with a way of using our proprietary crowd tools to target all the data to a single skeleton, and have the software and rigs work together so the animation could be used on the other nine elves. Textures all came from photographs taken of the various costumes and props. To help make 10 elves into 1,000 without getting too many repeats, texturing made many variations to the design of the waistcoats and shirts for the male and female elves. Shading then added another layer of variation by making the shader randomly select a color for the jacket, trousers and hat of each elf from a swatch sampled from all the fabrics of the live action costumes. For the actions, we established with Alex Bicknell a list of what we needed to capture, built the props required, and spent time at Audio Motion in Oxford capturing each scene.

"There was only one shot that used the crowd software in the traditional, simulation way; all the other shots used the captured clips that were positioned and timed using our proprietary crowd engine ALICE in non-simulation mode. This flexibility over simulation packages like Massive made it possible to treat each shot as if it was a hand-animated piece, whilst still managing to get first passes on shots with 1,000 elves in a matter of days. Then, clothing animation was simulated in Syflex. We rendered the shots using sub-surface scattering for our foreground and midground elves. Final composites were assembled in Shake."

Cinesite created most of the sleigh ride sequences which were a combination of the sleigh mounted on a mechanized gimbal shot against a bluescreen, and a fully CG incarnation, including the passengers, sleigh and reindeer. 

For lead elf Willy, another approach was required. The character provided the team with an interesting challenge as 6'1" actor John Michael Higgins had been cast as 4' Willy. Having recently supervised 1,000 head replacement shots on a little person for Little Man, Bicknell certainly had some experience in the field. "Due to the comedic script and frequent improvisation, David wanted Willy to be able to interact directly with Fred in situ, which excluded the use of split screen techniques for the majority of the shots," Bicknell recalls. "Armed with my experience on Little Man, I suggested going down the head replacement route. We first played all the scenes with a little person named Jorgé standing in for Willy and miming his body to match John Michael's dialog. Then, we waited for a first cut of the scenes, and embarked on four weeks of secondary photography against a bluescreen. We lined-up JM with the Jorgé plates, and set up eye-line markers to represent any characters or relevant objects that were represented on the 'A' plate. JM was seated on a swivel chair that allowed him to rotate his body to match any perspective moves that Jorgé's body made -- any travel through the set would be created as part of the digital composite. Whenever the camera move on the ‘A’ plate affected a change of perspective, I mimicked it by eye using a dolly on the blue screen set." More than half of the head replacement composites were created by Peerless Camera under the supervision of VFX Supervisor John Paul Docherty. These involved very complex paint work, motion matching and CG clothing/skin replacement, completed by a five artist "high speed compositing" unit centered on Autodesk Inferno systems. The rest was shared out among other facilities, including MPC, where half of the head replacements for Little Man had been completed.

Making Santa Fly
The final challenge of the movie was one that plagues most Christmas movies featuring the iconographic Santa and his unique method of transport; namely, the sleigh and flying reindeers. Early in pre-production, the team decided on a practical sleigh and real reindeers for scenes featuring the static sleigh. The two sleigh ride sequences were made up from a combination of the sleigh mounted on a mechanized gimbal shot against a bluescreen, and a fully CG incarnation, including the passengers, sleigh and reindeer. The backgrounds were sourced from helicopter footage shot on location in Chicago, stock footage sourced from round the globe, 2D matte paintings and fully CG environments.