Duncan Jones follows up his brilliant Moon debut with Source Code, a sci-fi thriller with Ground Hog Day overtones starring Jake Gyllenhaal as a soldier investigating a commuter train explosion by revisiting the incident in a continual eight-minute loop.

Louis Morin, the overall visual effects supervisor, hired six facilities to create more than 850 shots: Montreal-based Modus FX, the primary vendor, which contributed nearly 100 shots in-house, including complex digital crowds, CG trains, environments and dramatic pyrotechnics, and another 60 train station assets for the other vendors; Rodeo FX, which crafted most of the greenscreen windows for the train interiors; MPC Vancouver, which handled the big explosions and crash sequences; Fly Studio, which provided key transitions; Mr. X, which did additional window backgrounds; and Oblique FX, which created bomb interiors, a virtual stuntman and a slow-motion explosion sequence.

Seamless photorealism was vital. The shots featured hundreds of greenscreen windows showing passing landscapes or train station backdrops, and the use of CG in post allowed Jones and the actors to work without outside distractions during production. Set extensions on the train station were also crucial, especially since they decided to change the parking lot. That meant more than 65 additional shots, but these also provided logistical maneuverability as well as flexibility with the storytelling. Editorial, meanwhile, was done in tandem with VFX, allowing them to be ahead of the curve, so to speak.

Modus, which previously worked with Morin on Barney's Version, began early on Source Code. "We started doing the previs for the main action scenes --how the train would explode, and where this would take place -- so we were responsible for the feel and pacing of the key effects sequence," explains Yanick Wilisky, VP of production and vfx supervisor at Modus.

However, once these shots were roughed out, Wilisky says they were handed over to MPC Vancouver for completion because Morin wanted a more experienced touch. Thus, Modus was able to do what it does best, focusing on exteriors of the train and the station, including reflective windows and the metallic surfaces of the train. Modus also created the CG commuter and cargo train models for the team at MPC, as well as shots depicting enormous traffic jams: lots of virtual crowds and cars for plates of the superhighway in Chicago, which were shot from a helicopter.

"The action takes place in Chicago but lots of it was filmed in Montreal, so we had to do CG replacements of the environments," Wilisky continues. "So we did a mix of Google Maps and other stuff to survey the area and then we went and took lots of pictures and from there we created an accident. And Duncan would say, 'Let's try another area of Chicago.' So we did three different areas until we figured out exactly the action. At the time we were working with Paul Hirsch, the editor, and he was working with us on a lot of versioning. And the final result is 1:1 with what we prevised.