Tolkien's three novels - The Fellowship of The Ring, The Two Towers, The Return of the King - were published 1954-55 and first made into a single underarchieving feature-lenght cartoon by Fritz the Cat creator Ralph Bakshi in 1978. Since then the classic tomes have long been considered too complex, too grand and too expensive to attempt in live-action form. There's also the novels' huge and fanatical following around the globe - fans who are easily piqued and liable to revolt if they feel the story of Frodo Baggins, Sam, Gandalf and friends aren't getting the lavish treatment they deserve. Perhaps filming a giant ape climbing up a skyscraper would have been a safer opinion.

However, Jackson has gone ahead with his plan and, almost a year after the original announcement, details are at last being finalised on what will be New Line Cinema's largest undertaking yet. The studio has shelled out around $ 190 million for the trilogy, which is set to start filming this autumn throughout New Zealand - a country Jackson feels can best capture the essence of Tolkien's mystical domain.

Hobbiton is now on a farm on the North Island, while Edoras is taking shape on the outskirts of Canterbury.

The scripts for all three movies have already been written by Jackson and his long-time collaborator Fran Walsh, helped by first-timer Phillipa Boyens and Stephen Sinclair (who worked with Jackson on Braindead and Meet The Feebles). The trio of films will be shot back-to-back in a marathon 18 months, before heading into post-production for a period of similar lenght.

Much of the work will be undertaken by Kiwi computer effects house WETA, which recruited by posting large adverts in the trade press calling for digital technicians to "champion your craft and make history". WETA has been charged with reacreating Tolkien's Middle-Earth, as well as the 1,200 CGI shots required by the production. They have spent the last two years constructing thousands of miniatures, creatures, weapons and armour for up to 20,000 extras.

Meanwhile, Jackson has busied himself by drawing a number of sketches of scenes from the movie, which have been fleshed out by the effects team into richly textured storyboards, samples of which can be seen on these pages. Among them is the scene in which Gandalf is seen standing in the Mines of Moria, towered over by the behorned shadow of the Balrog, and a romantic interlude on a bridge between Aragorn and Arwen. They also give some idea of the huge scope of the movies with sprawling landscapes, dazzling waterfalls and beautiful snow-capped peaks. Similary, a shot of two hobbits sneaking a look at the advancing hordes of Sauron demonstrates how sophisticated WETA's computer technology is, transforming 15,000 extras - wearing armour made out of string by the ladies of the Wellington Knitting Club - into an unstoppable 100,000- strong evil force.

Meanwhile, the frenzy surrounding casting can only be rivalled by Star Wars Episode II. Confirmed are Elijah Wood (The Faculty), who has signed to play lead hobbit Frodo and former Goonie Sean Astin, who will play his sidekick Sam Gamgee. Recent additions have included the muchlauded appointment of Sir Ian McKellen as the mystical wizard Gandalf (a role wich will tie him up for a staggering 11 months), while Ian Holm has agreed to take the part of Frodo's uncle Bilbo. Elsewhere, the prize role of the knight Aragorn has been nabbed by young Brit actor Stuart Townsenf (Shooting Fish) and Secrets and Lies' Timothy Spall will play the dwarf Gimli. The weaselly Gollum, however, will be a totally CG creation.

Otherwise, some big-name cameos are still being considered - including Sean Connery as baddie Saruman - while Jude Law has apparently been earmarked to play Legolas. Emma Thompson, Kate Winslet and Christopher Lee are also rumored to be mulling over possible appearences.