Guardians of the Galaxy had a record-breaking opening weekend and Framestore has revealed its work on the deep space comic adventure.

In creating VFX for James Gunn's film, for Marvel and Walt Disney Pictures, Framestore developed one of the universe’s most unlikely bunch of heroes in the form of Rocket Raccoon (voiced by Bradley Cooper). The studio animated both him and his arboreal companion Groot (Vin Diesel) in the middle act of the movie, one that spans more than 40 minutes and 633 final shots. Framestore also created the cavernous expanse of Knowhere – a giant, mined-out skull which is home to a whole city. The VFX studio described as the most complicated environment it had ever built.

The work was overseen by VFX Supervisors Jonathan Fawkner and Kyle McCulloch, with the latter on set at the UK’s Shepperton and Longcross studios.

“Our first creative challenge was creating a believable talking, bipedal raccoon,” explained Animation Supervisor Kevin Spruce. “Rocket needed to look naturalistic, but at the same time he had to be made to do things raccoons don’t do. Like shoot people with a big gun for instance. If you exaggerate his performance and make him too cartoony you’ve lost the audience but if you go too real it won’t be entertaining or won’t do Bradley’s voice justice.”

Framestore's Creature FX team had their hands full with Rocket's fur and clothing. Normally when VFX artists need to simulate a million hairs for a coat of fur, they might choose 10 percent of those as guides to drive the full groom. However for Rocket Framestore simulated every single hair and how it collides for the first time.

“Rocket is the strongest and most central character that we have animated without a doubt,” explained Jonathan Fawkner. “Underneath there’s a lot more to him than just anger and as a title character he’s got sequences that posed really beautiful challenges from an animation and an acting point of view. We had to make sure he could hold his own on screen.”

One section of the film begins with the heroes captured and transferred to the Kyln prison. One of the biggest sets Marvel has ever constructed, Framestore still needed to extend it from two storeys to 30. Where normally you might use a matte painting, the set extension was fully built, lit and rendered by Framestore. This was deemed essential as the environment was to be viewed from so many different angles .

Knowhere, a city inside a severed head floating at the edge of the Marvel Universe, became Framestore's most complicated environment build so far – three miles across and designed with distinct neighbourhoods comprised of 85,000 separate pieces such as towers, pillars, turbines, favela huts. The VFX studio brightened up those districts by hand-placing around 10,000 street lights. Other vfx shots included creatures to be animated on the gambling table and the animation of a high-speed spaceship chase that explores every inch of Knowhere.

"The chase takes place at hundreds of miles an hour," ” said VFX Supervisor Kyle McCulloch. "So from shot to shot the action might travel a quarter of the way around the environment, meaning you soon see every part of the environment. The camera takes in all the geometry, from large-scale things such as the towers right down to individual little railings, light fittings and doors. Our part in James Gunn’s hilarious, hyper-colourful entry into the Marvel canon ends shortly after the dogfight. It was fantastic to work with such an unlikely group of heroes and to help create such a complex one in Rocket.

"The best part of this movie was James being so engaged and involved from beginning to end," said McCulloch. "He wrote it, it’s his baby, and it was wonderful to work on a project where people cared so much."