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After tackling the Vatican in Angels & Demons, CIS Vancouver was ready for the demands of digitally reproducing The White House and surrounding Washington DC for the action-packed political thriller, Salt, starring Angelina Jolie as a suspected double-agent.

"The White House is an icon," asserts Robert Grasmere, the overall visual effects supervisor, who describes the action as hyper-real for the Philip Noyce-directed Salt. "It was a pretty daunting task because we couldn't shoot at the White House or build a set or even put up bluescreens. These were front and center shots. So the work CIS did looks pretty real -- it all came through."

The reason it all came through is because of CIS' skill and visual effects repertoire. They shot the Grumman Air Force base and constructed two White House gate posts in the parking lot with gates, and then dressed up the ground a bit, added some grass on the other side of the fence and marked out with chalk the general curve of the road that goes in front the White House. CIS shot everything in one night and had their plate.

"We got the plates back and quickly worked on a temp version while working on the textured version that looked like the White House after we'd gone to Washington DC and taken hundreds of photographs," explains Mark Breakspear, CIS visual effects supervisor. "And we used that to build our model. Version two looked real. We refined it and put in digital trees and a complete synthetic skyline of Washington. We added digital humans, so we dressed up a couple of CG characters in security and army uniforms and then walking up the steps to the portico of the White House. "

Of course, because they were only using the north side for the action, CIS didn't bother building the other side in CG. That is until they decided to re-shoot the ending to relocate this crucial sequence on the south lawn. "So we had to now build it," Breakspeare continues. "It was probably the most inefficient way to build a model in CG, with putting all of your forces off to one side and thinking you're done and then going back and rebuilding the backside.

"It was much harder because it is a lot bigger and your closest vantage point is right on the bottom. We ended up going up the Washington Monument because there's a good vantage point from the top. We worked with the Secret Service to get special permission to take our photos with a tripod."

Salt has been captured and is taken away in the helicopter outside the White House. This raised several issues: we see all of Washington DC behind the White House, so CIS opted to do brute force with roto. It was too expensive to do a complete 3D model of the city, and a matte painting was going to look too flat.

"We came up with a clever way of accessing a free data set available from the US government, which told us where all the buildings were," Breakspeare adds. "We realized that if we were take images from the right angles and project them onto the boxes from the data set, we would get a very convincing cityscape night shot in 3D. One of our programmers wrote a plug-in that would take this government software and reconfigure it into useful geometry that we could use. We did a very simple 2.5D model of Washington DC going back 20 miles with simple geometry and simple textures, but it rendered quickly. He populated the streets with cars and headlights and rendered that as a separate layer."

They used Maya for the animation but switched mid-stream from Shake to Nuke for the more complex compositing. Since the facility was transitioning anyway to Nuke, it seemed like the best solution. "On paper it was suicidal," Breakspeare notes, "but we had played our hand and it turned out surprisingly painless. Nuke is amazing and, quite honestly, if we had tried to use Shake for the second half of the project, it would have come up short."