I was a bit surprised when I heard they were doing it in three parts as well. 2 made sense. The story is big enough that one wont work at all without cutting out huge sections. I suspect that it was about breakpoints. As you mentioned, you'd want the first part to conclude with Bilbo finding the ring and escaping Gollum's cave (perhaps with a bit of fade away of Bilbo protectively covering the ring after lying to Gandalf about how he escaped). But if you break there, there's a lot of story to tell in the second part. I guess I can kinda see it because of that.
I agree that they're probably going to fill in a whole lot more stuff that wasn't in the original story, but might leave viewers not familiar with the book wondering. For example, Gandalf repeatedly leaves the group to their own devices, periodically showing up again to provide them direction or advice. In the book, it's never explained where he goes or why. He's just a busy wizard doing busy wizard stuff and can't spend his whole time with this one group apparently. But in the film, they'll have to explain this. I suspect they'll create some sequences of Gandalf helping them from behind the scenes. I think they'll also spend a lot more time developing the back story of the battle of the five armies. In the book, they just kinda all show up claiming a share of the treasure. So some of the extra stuff in the second film could be used to set that up (folks find out that Gandalf is helping a group to take down Smaug and start jockeying for position in case they succeed). They'd also want put in a lot more detail about the Lake Town people. In the book, it's almost an afterthought. Tolkien wrote the book the way he told the stories originally (to children, and kinda making stuff up as he went along). In the films, they'll have to significantly expand several parts to fill in the gaps that were in the original.
So yeah. I do see how they could spend 3 films telling the story. I also suspect that the studio is wanting to stretch it out as much as possible. It's a huge potential money maker. Also this is the last feature film you can really do based on Tolkien's world, so from an artistic point of view, you'll want to fill it with as much material as possible. You can also fill in detail that will lead more smoothly into the existing Lord of the Rings trilogy. Ultimately, you want folks to watch the Hobbit films and then the Rings films and get a full complete story. Filming them out of order is actually an advantage in that you know exactly what stuff you need to add in order to do that. Of course, that's also how you end out with a story that could potentially be told briefly in one film, or well in two, take up three full length films.
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King Nobby wrote:
More words please