Hobbit film director Guillermo del Toro says designing the movie has taken almost a year, three times as long as his other movies such as Hellboy.

This is despite having three or four times the number of artists used on other films, and the production of drawings and character models will continue through to the start of filming after the summer, he said.

The director told the Total Film website the two Hobbit films would follow the structure laid out by the book's authors, Professor J R R Tolkien but will fill in gaps, such as what the wizard Gandalf was doing when he was absent from the action in the book.

Del Toro was asked whether the films will stick to the creature designs from Lord of the Rings, but said they would be changing.

"I also wanted some of the monsters in The Hobbit to be majestic," he said.

"I wanted the Wargs to have a certain beauty so that you don't have a massively clear definition: what is beautiful is good and what is ugly is not. Some of the monsters are absolutely gorgeous."

And the director - who confessed he was already "creeped out" thinking about the Spiders of Mirkwood - said he was proudest of the dragon Smaug, for which he has come up with an idea to make it different to all the other dragons on film.

"The bulk of the design took about a year ... because of the unique features of the dragon."

He said there was a lot of magic in the film, and said it had a bit more poetic licence than the Lord of the Rings trilogy directed by Peter Jackson, who is producing the Hobbit films.

The Hobbit begins shooting at the end of the summer, and the first film will open in 2011.