Lighting
There are five main locations in which the story unfolds: the tree top, sliding down the tinsel, the train, the piano, and the airplane. Each location required its own lighting setup, so I created five scene files expressely for this purpose, using between 21 and 31 lights each. The train and airplane sequences were the most complex, requiring a lighting rig to follow the vehicles as they moved.
Most of the key lights were set to warm colors, with ambient set to cool for extra depth in the shadows. Negative lights were used to darken the wall behind the tree and two corners of the room, and all other shadows were calculated using shadow maps. The shadows contributed a lot to making the environment look gritty and realistic. The tree itself had three dedicated lights: two distant key lights and one omni at the base to illuminate the underside of the branches.