This scene also required special effects, stunt work, and figuring out how to portray vampires fighting at very fast speeds. Overseeing the visual effects department for "New Moon" was Susan MacLeod, who had previously worked with Weitz during the production of "The Golden Compass". MacLeod enlisted Tippett Studio to create the computer generated wolves, while Prime Focus of Vancouver handled the effects of the vampires. To prepare for the aggressive task of making the wolves look real, Tippet artists studied wolf culture. They also were able to reflect leadership and human muscle size by adjusting certain features of the wolves, such as their fat and height. In February 2009, a group of artists were able to travel to Wolf Mountain Sanctuary, outside of Los Angeles, and see real wolves. The artists were able to observe the behavior of both the timber and arctic wolves, who ran in packs of three to five. The idea was to give everyone a deeper feeling of the creature that they were creating. MacLeod explained that creating the shape-shifting werewolves was not an easy task. The wolf work included shooting "plates", or photographic imagery into which CG creations are integrated. Since the book described the wolves as being as big as horses, full-scale aluminum and board wolf cutouts were used as a visual reference for both actors and crew members. Once the actors had a reference, the cutouts would be removed allowing the cameras to capture the scene. In order for the CG wolves to be in sync with the live action cameras and actors' movements, the team used match movers, a land surveying tool that recorded the shooting location's topography with reference marks. A raw 3D model of Jacob's wolf was the basis for creating the others. A muscle system, which gave the appearance of muscles firing and flexing, contributed to this model. From there, the initial fur layout went to painters who were responsible for its color and groom. They also added characteristics, such as wet hair clumping together, and applied it to the fur. They refined this look before passing it off to the lighting and technical directors. One challenge for the production team was how to convey Bella's depression once Edward departs. In the novel, these pages were filled with the names of the passing months, and in the movie, would be represented as a visual effects shot with a camera circling around Kristen Stewart. The window that was used for the original film did not quite fit what Weitz was looking for, so the production team created a bay window when recreating the Swan house.