Matt Reeves' Let Me In (the Americanized reworking of the Swedish vampire film, Let The Right One In) is so deliberate in the way it's crafted that the vfx needed to be complementary to this tender yet horrific allegory about adolescent angst.
"Matt had a strong desire that this film not feel smaller than the original," suggests Brad Parker, the overall visual effects supervisor. "At the same time, he didn't want to overdo anything with ridiculous over-the-top visual effects. The vast majority -- and there are well over 150 shots -- are transparent."
However, it was the spectacular car chase that got Parker involved in the project, having overseen the climactic car chase in We Own the Night. "James Gray, the director of We Own the Night, is a friend and he talked to Matt about his car chase sequence, so that's how I came to work with Matt, and it was the first shot that we ever discussed," Parker continues. "He wanted it to be very first-person in the car with him as he crashed. He didn't know how he wanted to do it or how it was going to look, so we went through a quick development process, prevising out the sequence with an amazing supervisor, Casey Schatz [simulcam supervisor on Avatar , now at Giant Studios], who prevised all of the Let Me In sequences by himself. Once we had a sequence that Matt was happy with in terms of impact, it was my task to actually figure out how to do it.
Indeed, Faden, Method's visual effects supervisor, admits it was one of the most challenging shots, which required their compositors to combine two plates of what would total a 1,110 frame shot. "The tasks here were threefold," Faden explains: "First we had to create a realistic environment outside the car; second we needed to create an animation that would blend with the first part of the shot and tumble down the digital hill in sync with the natural motion of the rotisserie, adding large bounces where appropriate and traveling the proper distance; third, the marrying of the two plates required that we blend not only the actor and stunt man but also the details of the two Impalas.
"The background was created using an HDR of a location shot on PCH and then projected onto low detail geometry. This was blended together with a road, fence, and hillside complete with plants and shrubs in cards rendered in V-Ray through Maya  by our CG Supervisor, Juan-Luis Sanchez. The car tumble animation was completed in Houdini  using CHOPS (channel operators) to blend the tracked car animation from the A-side to a hand animated B-side. CHOPS were also used to add procedural shakes and bumps on top of the blended curves based on wherever changes in velocity were detected (hitting the ground). Debris and smoke were also created using Houdini and Mantra. For the plate transition, we used both Flame  and Nuke  to hand-off from one plate to another, carefully offsetting each transition so that you would never feel that too many things changed at once. We were asked to not hide too much with camera shake, which is how these sorts of transitions usually would take place, so we had to get extra creative in how we switched over. In addition, Compositor Nancey Wallis used Nuke to transition the BG by layering a lot of the B side lights into the A side gas station plate as we are panning or skidding across the road."
According to Faden, each character had cloth and hair simulations performed using Ncloth in Maya and were lit using RenderMan  through Houdini. "For each shot where we knew we would be doing a digital double, we shot reference of the actors in the actual lighting, doing something similar to the required action, which helped our animators, lighters and compers across the board," Faden adds. "In the end, it was a combination of careful fight choreography by Anim Supervisor Matt Hackett and animators Joon Lee and Christina Sidoti, and detailed comp work to blend the rendered characters into the plates."
Making Abby bleed when she enters Owen's (Kodi Smit-McPhee) was a daunting task as well. "It required a spot on face track while the actress was actually shaking, as well as a Houdini developed dripping blood technique created by Nordin Rahhali," Faden continues. "The shots were comped by our supervisor, Jeff Allen, who perfected the face tracking using a Nuke based magnet tracking plug-in, which we created at Method for Freddy's face on A Nightmare on Elm Street. It allowed us to pinpoint problem areas and stick them to the actress' deforming skin."
Meanwhile, Dive, working under the supervision of Mark Forker, developed the look of Abby as she transforms into a vampire (removing her hair, creating throbbing veins and darkening the skin around her eyes, augmenting the actor's features with digital makeup), and a character burned by acid in collaboration with Invisible Pictures (3D modeling and skeletal scans of the actual actor in make-up began the process so that parts of the face could be subtracted while digital prosthetics created the inner and outer half-mouth). Dive used Maya, Nuke, Sapphire , Furnace, SynthEyes , Mocha  and Silhouette.
However, the long opening and closing shots required a snow system to depict the haunting wintery New Mexico landscape.
"The snow system was built on Maya sprite particles and dynamics," Forker describes. "Using a few reference shots from a few different scenes, I matched the motion of the falling snow and began adding controls for adjusting wind, size and volume of the entire system. There was also some control over making sure particles got killed after leaving the camera's view in order to keep simulation and render times down. Visually, the snow varied in multiple scenes from larger, fluffier flakes to more crystalline, icy flakes. I could dial in the heavier look of the icy snow using the controls built earlier and then added additional passes for sparkle which could be finely adjusted in comp. Multiple depth passes were rendered out for compositing using a GPU- based renderer: this allowed us to generate multiple revisions without too much of a render time hit. Lighting, final color and occlusion were handled in comp. Special cases where see the snow land, melt or blow through specific areas were handled with additional particle systems inside the larger simulation."
Bill Desowitz is senior editor of AWN & VFXWorld.