Les Misérables' compositing supervisor Greg Spencer talks about the visual effects done for the movie, including realizing Tom Hooper's direction to make the skies into another character in the film.
Says Spencer, "We needed to get a solid idea of what each sky looked like before we started. We knew there would be a lot of roto involved so while that was getting done, myself and the VFX Supervisor began taking single frames from what we considered 'hero' shots and began throwing as many skies into them as possible. That way we could see what did and didn't work. It was a quick way of getting a strong visual idea of how things would look. When we had narrowed it down to two or three skies, we chose a few key shots from each of the scenes and did rough versions to see if they would work on the move. We also did a couple of matte paintings of the city."