Behind the Magic: Anatomy of a Shot - 'Marvel's The Avengers'

I find these behind the scenes videos really interesting, especially when comparing what's actually filmed to what you see up on the screen.

While 'The Avengers' posed many visual effects challenges, one of the larger challenges was pulling together the "tie-in" shot during the third act of the film. Rather than frames, this single shot is measured in minutes on screen and is one of the longest effects shots in the film. It incorporates both practical special effects and extensive digital visual effects. The New York City environment that serves as the setting for this shot (and virtually the entire alien invasion) is computer generated by the visual effects team at ILM.


via