Jackson said the decision to the turn the two-part film into a trilogy was based on "the richness of the story of The Hobbit, as well as some related material in the appendices of The Lord of the Rings".
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While Galley Cat saw it this way:
Here’s more from the director:
We were really pleased with the way the story was coming together, in particular, the strength of the characters and the cast who have brought them to life. All of which gave rise to a simple question: do we take this chance to tell more of the tale? And the answer from our perspective as the filmmakers, and as fans, was an unreserved ‘yes.’ We know how much of the story of Bilbo Baggins, the Wizard Gandalf, the Dwarves of Erebor, the rise of the Necromancer, and the Battle of Dol Guldur will remain untold if we do not take this chance.Jackson discussed his upcoming film adaptation of The Hobbit: An Unexpected Journey at San Diego Comic-Con.
The Wall Street Journal reported that convention attendees received a 12 minute-preview of both Hobbit movies which included scenes that featured “Bilbo Baggins (Martin Freeman), the wizard Gandalf (Ian McKellen), royal elf Galadriel (Cate Blanchett), 13 dwarves and the ring-obsessed creature Gollum (Andy Serkis, who also served as the production’s second unit director).”
Check out this photo album to view pictures from the event. So far, New Line Cinema has uploaded seven behind-the-scenes video blogs on The Hobbit‘s official Facebook page.