Digital backgrounds were created to bring to life the tale of Hughes’ airplane crash in Beverly Hills.

No such problem existed when Sony Imageworks created the virtual environment for The Aviator. “They did full clouds that would behave in 3D,” says Legato. “We originally thought that the clouds would cover so much that we’d get away with murder. Because we didn’t have a ton of money to do this, we thought we would use the cover of clouds to hide any problems, but we didn’t need to. The guys at Sony Imageworks made it perfect — so anywhere we wanted to shoot was fine. We could carve out an area without worrying whether clouds were there to cover it up.”

Legato credits Sony’s digital effects supervisor Pete Travers and CG supervisor Dave Sieger with making the process go smoothly. “They updated something that Sony had used on The Polar Express to create clouds. But for us, they made a photoreal version. It’s sort of a particle system `bed’ that the real cloud information was projected onto. They created, basically, the geometry that the cloud information was texture mapped on top of. It’s texture-mapped in such a way that I would imagine it is in little tiny chunks, like NURBS splines. They looked very realistic.

“You could view it from any angle because they broke up the real clouds into so many textures that when these pieces were reassembled they had all the texture of real clouds. My version of what they did is to imagine that you take a picture of clouds and divide it into a thousand tiny squares. Then you take those tiny pixels as texture maps that are literally sprayed onto this geometry. Basically every angle you see is of a cloud. Then they applied lighting on top of that. It’s very difficult to tell how a cloud is lit. So the pictures are probably fine enough for a texture map that it creates the illusion of three-dimensional clouds. It’s kind of like combining texture mapping and particle systems. The particles that were created didn’t have to be that fine because they’re really just holding picture information. It probably only works really well when you do it with things that are sort of amorphous. If you chop up a picture into thousand pieces and put those pieces on top of particle geometry, each piece of that puzzle is random-looking enough that it works.”

A progression from wireframe to completion of the Hell’s Angels’ sequence.

One final bit of verisimilitude in this virtual environment was the illumination of the sky. Legato explains, “What we did on this film that we didn’t do on Harry Potter was that as you fly around the sky dome, the sky is lit up appropriately. If you’re looking towards the sun, for example, the sky is very light in color. When you shoot at a 24° angle to the sun, for example, it’s very deep blue. And you have all the variations in between. In Harry Potter, we didn’t really do that. We had a generic sky dome.”

One unique aspect to the visual effects work in The Aviator was the post-processing that Legato did to emulate the vintage Technicolor processing in Hell’s Angels. For the film’s original release, Hughes had the prints hand-colored, including an eight-minute two-strip Technicolor sequence of the film’s female star, Jean Harlow. Scorsese wanted to evoke that look in portions of his film, notes Legato. “Way back in 1927 the only color process that was available was two-strip Technicolor. So you could only use red and green. If you shot a blue sky, the blue sky would always be this cyan green, and it tended to look artificial and not like real life. Marty’s version of how he was going to tell the story is that if he were filming Howard Hughes at the time and wanted to use color, he’d be limited by two-strip Technicolor. So that’s what he chose to do.”