MWD - Zodiac, Page 2 of 3

After getting away with his murders in outlying areas, the Zodiac chooses downtown San Francisco for his next victim. We listen to radio talk shows speculating wildly about the killings while a series of Matte World shots show the city from a floating perspective. Soon we discover that we have been watching as the killer has hailed a cab and driven to the site where he will murder the driver.

At the height of the killing spree and public turmoil, the Transamerica Pyramid structure was beginning to take shape. The sequence begins emerging from the clouds to reveal the construction pit and early steel truss work. It's an entirely CGI shot, using aerial photos of San Francisco buildings for photogrammetric recreations of the neighborhood.

The killer hails a cab in the busy Theater District. The digital camera used to shoot Zodiac is very sensitive and performs well on night shoots, but the sky and distant buildings are still too dark to be picked up.

MWD filled in the sky and extended the street with more period buildings. An advertisement for "Hair" is a restrained period touch.

Once the killer is in the cab, Fincher wanted the camera to follow from an overhead perspective perfectly locked to the car. It's a highly artificial view, but when coupled with a realistic rendering, it creates an unsettled feeling in the audience.

The shot could have taken an enourmous amount of detail to build as a complete 3-d environment. As a more practical approach, we collected overhead photographs from rooftops and mapped the photos onto relatively simple geometry of the buildings and streets. The cars required more complete models to allow for shadows and reflections from lighting.

The San Francisco photos provide a great deal of complexity with low rendering "cost".

For foot traffic, we photographed actors walking across a bluescreen from the roof of our building. Getting the perspective to match is a sort of cheat. In theory, we would have had to use a moving camera matching the scene camera. By cleverly placing the elements, though, we were able to match the perspective using a tripod-mounted camera. Computer-generated people fill in a few gaps where the bluescreen people couldn't work, but the real people have more natural and complex motion than can be quickly generated in software.

The cars in the frame seen here are all CGI, but in other parts of the shot we were actually able to use store-bought miniature cars photographed stop-motion to get the complex highlights without the long renders and endless tweaking that cg cars require. We love using "real" elements like this to keep our CGI shots honest.

Revisiting the San Francisco waterfront for a night version, Matte World modelled the Bay Bridge for a flyover. >

Flying past layers of fog, we see the bridge towers framing the waterfront skyline and its lights reflected in the bay.