Metro sat down with Sir Ian McKellan and asked his why The Hobbit films (originally two) has now became a trilogy, even though The Hobbit book is the smallest out of all of Tolkien's works.
“I thought it was pushing it to make even two films, which is what we were originally doing,” he said, “but then I realised that one of the reasons it does spread into a trilogy is that Tolkien can describe something in under a paragraph that will take far longer to replicate on-screen. For instance, ‘the army advances’; that’s only three words but involves a lot of visual action. It isn’t that the book has been expanded I suppose, it’s that it has gone into all its detail.”
He then went onto speak about Benedict Cumberbatch's performance as the dragon Smaug which was completely done in motion capture, which Sir Ian is confused about.
“Doing motion capture for a part such as that is tricky, I mean how do you play a dragon? Then again, before Lord Of The Rings people were saying how on Earth do you play a Gollum?’”
The Hobbit: The Desolation of Smaug hits theaters December 13th 2013