Finessing the Muppets
No, they didn't mess with the Muppets by going CG. But Look FX did do a lot of blue screen work because Kermit's green, of course. They didn't want to carry around two sets of screens.
"The one-word description I would use is 'finesse,'" suggests Max Ivins, the VFX supervisor for Look FX. "This is not a brute force, tour-de-force use of CGI. It was a finesse job of how to get those hairs from the Muppets back into the shot. And also how to roto out and get rid of all those puppeteers heads and everything else that's out of place. There were some pretty incredible rig set ups to enable the puppeteers to do their thing that in the past you wouldn't have seen."
For instance, there's a scene where Beaker runs around in circles and, considering that he's less than half a foot tall, they built a carousel with a platform on top so the puppeteers could hide below Beaker and get him to perform convincingly. There was a grip that spun the carousel with the four puppeteers on it.
"They went all out to make these rigs so these things could be done, so in that sense, it's a traditional visual effect show," Ivins confirms. "It wasn't about making three-dimensional puppets and animating in CG at all. Our main mission was to enable the puppeteers to do cool things. This was much more satisfying than trying to Mupp around with them."
In fact, it's getting to the point where they can just about roto out everything. "It strikes me as very similar to a lot of what we did on Captain America," Ivins continues. "We were given a bunch of shots of him on greenscreen or on a motorcycle completely over green, and we built the backgrounds and compositing him into it or driving away from giant explosions. And this was another economical way of shooting in a studio rather than going on location, so we did set extensions and bluescreen composites."
But there's definitely a lot of action and dancing in The Muppets. In the opening dance number where we're introduced to Walter, the new Muppet, he's very active. He climbs up on a dresser and jumps onto the door knob and flies through the kitchen, resulting in cereal spilling all over. That was pretty much head to toe, full-body puppeteering. "All of it was shot to backgrounds that they had shot for it and then you played that back for the puppeteers," Ivins explains. "And that gave them the freedom to do more, wearing these blue costumes. And our joke was that made them invisible."