“I Am Legend” officially becomes shorthand for “obnoxiously intrusive, seemingly eternally omnipresent film shoot”:

Don’t be alarmed by the fleet of Black Hawk helicopters and military ships converging on the Brooklyn Bridge tonight — it’s only the new Will Smith movie, police said yesterday.

For the next eight days, these mock military vehicles and more than a thousand extras will shoot an evacuation scene for the next Big Willie blockbuster, “I am Legend.”

The post-apocalyptic sci-fi flick is due out this December.

Filming will start at 4 p.m. and is expected to wrap up weekdays at 10 p.m., police said.