After years of legal wrangling, dozens of setbacks, a switch of directors, a health scare, an earthquake and a race row – production has finally started on The Hobbit films in New Zealand. We've put together a fact file on the troubled production – with everything from major castings to the finer details.

About the film
Based on the iconic novel by JRR Tolkien – and the prequel to the massively successful The Lord of the Rings – the film will follow the journey of the hobbit Bilbo Baggins, who is swept into an epic quest to reclaim a lost Dwarven kingdom, conquered by the dragon Smaug. Hailed as a great "burglar" by the wizard Gandalf, Bilbo joins a company of 13 dwarves led by the legendary warrior Thorin Oakenshield. Bilbo's journey takes him through the wild; through lands swarming with goblins, wargs, giant spiders, shapeshifters and sorcerers – and the creature Gollum, where he gains possession of the magic ring that is tied to the fate of all Middle Earth.

Guess who's back?
Some of the stars from The Lord of the Rings have agreed to take up their roles for The Hobbit. Among these are Ian McKellen (Gandalf), Cate Blanchett (Galadriel), Andy Serkis (Gollum) and Elijah Wood (Frodo). Christopher Lee – who played Saruman in the fantasy trilogy – has said he will take up his role again, health permitting. Hugo Weaving (Elrond), Ian Holm (Bilbo) and Orlando Bloom (Legolas) are currently unsigned, but expected to return.

New faces
There was much speculation over the casting of Bilbo, with everybody from Tobey Maguire to Harry Potter star Daniel Radcliffe being rumoured for the part. However, the role eventually went to The Office star Martin Freeman. Richard Armitage (Spooks) will be playing Thorin Oakenshield – and the rest of the dwarven company will be played by Ken Stott (Balin), Graham McTavish (Dwalin), William Kircher (Bifur) James Nesbitt (Bofur), Stephen Hunter (Bombur), Rob Kazinsky (Fili), Aidan Turner (Kili), Peter Hambleton (Gloin), John Callen (Oin), Jed Brophy (Nori), Mark Hadlow (Dori) and Adam Brown (Ori). 

What's the hold up?
Lord of the Rings director Peter Jackson and his wife Fran Walsh originally expressed an interest in filming The Hobbit in 1995, as part of a trilogy – with the final two films telling the story of The Lord of the Rings. The years since have been plagued with legal wrangling over distribution rights and profits earned from Lord of the Rings, the financial woes of Metro-Goldwyn-Meyer and arguments over the budget (The two-part film is expected to cost around R3.4-billion to make).

These delays forced director Guillermo del Toro to pull out over concerns over scheduling conflicts, with Peter Jackson stepping from the executive producer role into the director's chair. The film was almost pulled out of New Zealand after actors' unions urged their members to boycott filming over pay and conditions. Then, when filming seemed certain to kick off, Jackson had to have emergency surgery on a perforated ulcer. Filming was pushed back even further after the earthquake in Christchurch on 22 February.

All of the delays led Freeman to acknowledge that he had heard rumours that The Hobbit was "jinxed". Production finally kicked off on 21 March.

The finer details
The Hobbit will be filmed in two parts, tentatively titled The Hobbit: There and Back Again and The Hobbit: An Unexpected Journey. The films are being shot in 3D,with Ian McKellen blogging that he had seen test shots of Bilbo in three dimensions. Despite rumours hinting at otherwise, the film will only draw on plot elements from The Hobbit and The Lord of the Rings – and not from The Silmarillion and Unfinished Tales, as filmmakers do not have the rights to those works.

The first part is scheduled for release in December 2012 and the second part will follow around the same time in 2013.

Go with what you know
After the massive commercial and critical success of The Lord of the Rings, Jackson was hardly going to change a winning formula. Like The Lord of the Rings, The Hobbit will be shot back-to-back in New Zealand. The film will be shot in the same studios (Stone Street Studios, Wellington). After The Lord of the Rings, Jackson kept the Bag End set (which he used as a guest house) and the scale model of Rivendell - so those are highly likely to make a reappearance in the films.

As with The Lord of the Rings, a lot of the sets will be built in scale – although there will be a greater use of animatronics and digital effects to keep with the times. Special effects company Weta Workshop will again be responsible for the film's sets, costumes, armour, weapons, creatures and the "bigatures" – the scale models of the sets used in the film.

Composer Howard Shore – who won three Academy Awards for his work on The Lord of the Rings – is returning to work on the score for The Hobbit films.