Turning Glasgow into Philadelphia for the Zombie Apocalypse of World War Z
There was a lot of work done by the matte painting team, a lot of re-projection work onto geometry. So, you have the ground floor of a building in Glasgow, but it becomes a real building in Philadelphia. Of course, there’s a lot of work done to make that blend seamlessly together. We got great feedback even from early tests. The filmmakers forgot that that what they were looking at was fake, which is a good compliment. There’s a shot where we’re looking down a street which is a canyon. Even the buildings right close up to the camera, they don’t exist. People said, “Where was that building?” Well, that building doesn’t exist. It’s in the computer. It’s not real.
We could create the canyons of Philadelphia and then in CG add in cars and cabs and fire trucks, crowds, things like that, to give that sense of scale. We had scenes where 50,000 people would run across the square. We used massive crowd sims. For example, there is a shot where you’re looking out the back of a helicopter as you’re flying over the city. So, for a shot like that, which no one would ever know, every single road in the live-action helicopter plate was digitally replaced. All the real moving vehicles that were shot at rush hour were removed. All the streets were painted clean, and then re-projected back onto geometry. Then we added CG cars jammed in traffic. We wanted to show the city gridlocked. The whole idea was the city was at a standstill. We didn’t want to see even in the background any cars moving. We had to remove all the traffic from the Ben Franklin Bridge and replace it with CG objects we’d created.
DS: I understand you used a lot of LiDAR scans.
MJ: Yes. Basically, we pretty much LiDAR scanned Glasgow by the time we finished with it [laughs]. We had a lot of reference of what the Glasgow buildings were. Aviv had a huge setup, like a robo-head, with a digital panorama camera, doing HDRI, multiple exposures on everything so you got the full dynamic range of the image. Aviv and I would go off and do these huge panoramas of the environments, detailed textures of buildings right down to the window level.
One of the environments I’m most proud of in the movie, skipping ahead from Philadelphia a bit, is when Brad and his family are being airlifted to safety and they have to make their way to the roof of an apartment building, which is in downtown New Jersey. That was the visual effects nightmare scenario. That essentially was done with a green box. It was a small roof-set piece, with just the top level they were standing on finished. Everything else was a complete 360 degree digital environment. Everywhere the camera looked, it was looking into a greenscreen. We had to create a world that doesn’t exist. There aren’t any housing projects like that in New Jersey.