20 Things You Didn't Know About Star Trek IV: The Voyage Home
19. The Iconic Shot Under The Bridge Went Through Several Revisions
Effects cameraman Pat Sweeney was tasked with creating the shot of the Bird-of-Prey swooping down from space and crossing under the Golden Gate bridge. First, they filmed the actual bridge in San Francisco, compositing in clouds and storm effects. This allowed the sense of scale that is shown in the film.
Then, they created a model of the bridge that would allow them to film up close. Forced perspective fooled the audience into believing that this shot was also of the real bridge, while this was filmed in the studio tank.
The actual shot of the ship swooping under presented a larger problem. Initially, a remote-controlled model was to be flown underneath. Sweeney knew that this would be a signature shot of the film, so it had to be done right. To his dismay, the model simply wasn't performing the way that they needed it to. He decided that the only option was to film it separately and, via motion control, composite the shots together. This allowed the epic image of a Klingon Bird-of-Prey to be seen hitting the waters of San Francisco's bay.