London-based VFX house Double Negative worked on a series of key visual-effects scenes for Paramount Pictures’ cinematic release of Stardust, including the iconic Sky Vessel.
One of the most keenly awaited Hollywood films of the summer – the fantasy adventure movie, Stardust – has London visual-effects house Double Negative to thank for many of its breathtaking sequences.
Stardust, directed by Matthew Vaughn (Layer Cake), is based on the graphic novel by Neil Gaiman, in which a young Englishman attempts to win the heart of a girl by going on a quest to retrieve a fallen star.
His journey takes him to a forbidden land beyond the walls of his village, where he finds the star has transformed into a beautiful girl, who is then hunted by a ragged crew of villains, pirates and witches.
It was Paramount Pictures’ production VFX supervisor Peter Chiang who approached Soho-based Double Negative with the offer to provide the major visual effects for the film. The Double Negative team influenced the creative side from the beginning, reveals Chiang.
“Vaughn had a very clear vision about the way the world should look, and felt the simpler the process the better. This was great, as he had a completely open mind and an ‘innocent approach’ that the film benefits from.”
Led by digital supervisor Mattias Lindahl and VFX producers Matt Plummer, Andy Taylor, Clare Tinsley and VFX co-ordinator, Emma Larrson, Double Negative produced 350 shots, making it the lead vendor on the film.
The main areas of work for Double Negative included the extensive photo- realistic environments, the Sky Vessel flown by pirate Captain Shakespeare, sky replacements, greenscreens and the magic effects used to differentiate between various witches.
The most difficult challenge – the Sky Vessel – was met by the production designer Gavin Bocquet, who made some minor alterations to its balloon shape during post-production.
CG supervisor, Rick Leary, designed the mechanism and dynamics for opening and closing the lightning nets. He says: “The director had been very clear in his brief: the vessel must look Victorian, and it must look the worse for wear.”
A major section of the Sky Vessel hull was built within a green screen set at Pinewood, with a heavily distressed look. It was Double Negative’s task to match the Sky Vessel identically with digital set extensions in keeping with this look.
“Most Sky Vessel shots needed CG topping up on the set construction, and in some shots the entire vessel was replaced,” explains Leary.
The team on the Sky Vessel was led by Lindahl and Leary in tandem with 2D supervisor Paul Riddle and 2D sequence lead Matt Twyford. Leary began work on the film early on in shooting, modelling the vessel from blueprints provided by Double Negative’s art department.
Once the full-size section of boat had been constructed on-set in Pinewood, Leary, along with texture artist Guy Williams, photographed every inch of the set to extremely high resolution.
Meanwhile, the modelling crew based back in Soho (Jez Smith, Jordan Kirk, James Guy and Emily Cobb) made the boat to a high level of detail and accuracy. Guy stitched the texture reference photographs in Double Negative’s proprietary software, STIG, and used other in-house tools, dnPhotofit and dnPlaneit to project and bake the textures.
Guy and look-development artist Bruno Baron undertook the remainder of the texturing of the boat’s hull and decks. Meanwhile the balloon, rigging and flags were modelled by Kirk and rigged by Gia Sadhwani.
By filming in front of a 360-degree greenscreen cyclorama, Chiang was able to offer movie director Vaughn and director of photography Ben Davis the flexibility to shoot from any angle – safe in the knowledge the ship could be invisibly extended in any direction.
Whether the camera was contained within the confines of the ship or free to drift far away into the air, the compositing team delivered a seamless transition from the live action set into the precisely matched CG ship, “even in a scene set within a raging storm which had the additional complexity of dense falling rain”, says Riddle.
Also integral to the Sky Vessel sequence was the need to illustrate the passage of time. Twyford was able to facilitate this “by creating a palette of looks, from early dawn, through midday sun to falling dusk”. Another feat that taxed the team’s expertise were the CG environments.
The geography is needed to show the relation of the real world to Stormhold – the film’s fantasy world – and those environments were used for the Sky Vessel sequences, and many other points in the film.
Double Negative says Chiang wanted “amazing vistas that would show the huge magical Kingdom of Stormhold”, and reveals that the live-action locations were in Iceland and the Isle of Skye, adding: “This provided guidance to the types of mountains and geography that were required, but outside of this, the Double Negative team was given a free hand to design the landscape as we saw fit.”
For the Sky Vessel shots, TECTO Survey data of the Isle of Skye was used for the near ground, and a 3D cyclorama of mountains was constructed for the background.
The sky dome was created from photography, stitched together with STIG and rendered latitude/longitude of 24,000 pixels. The vessel was match-lit, and digital doubles set up for the deck.
Lindahl says: “The film is a fairytale, and so a lot of the VFX were required for major story points and had to demonstrate the geography of the world that we are taking the audience into – so it was magical, but also had to be realistic. This is a fine line to walk and a challenge that we had to measure up to.”
On his odyssey, the love struck lead, Tristan, finds the falling star, which has transformed into a girl named Yvaine. But he’s not the only one seeking her: a king’s four living sons – and the ghosts of their three dead brothers – all need the star as they vie for the throne.
Tristan must also overcome an evil witch, Lamia, who needs the star to make her young again. Tristan encounters multiple witches, and each required signature magical effects.
Lindahl says: “Lamia’s green magic effect was briefed initially as a fluid, controllable fire. However, the brief evolved quite rapidly, to vary the effect from a gentle twisting finger of flame to a raging inferno. The intensity of this is dictated by Lamia’s emotional state.
“The evolving brief required a change of approach to the magic effects and required a far greater range of characterizations.”
2D sequence lead, Christoph Salzmann utilized both photographic elements and CG fire to realize this, while dynamics technical director Pawel Grochola developed a novel approach to generating 3D fire using particle and joint-driven softbody ‘ribbons’.
Another key witch is Sal, whose magic effect Lindahl says was briefed as “black smoke”. He adds: “A great deal of design work was done in-house under the supervision of Gavin Graham, regarding its movement and technical execution.”
Sal’s smoky magic was used to illustrate transformations, such as a mouse being turned into Tristan and back again. Says Graham, “Normally you would create a smoky figure, turn it into a cloud of smoke and reverse it, but Sal’s smoke needed to be more sophisticated than that.”
In fact, the colours of the original object needed to flow through the smoke effect and then recreate themselves into the final outcome. Because Vaughn wanted this magic to feel rooted in reality Graham aimed for “gritty and dirty, like diesel smoke”.
With fluid simulations being notoriously difficult to art direct, 3D artist Bjorn Henriksson used a wide variety of Double Negative’s in-house fluid tools to turn animated geometry into a target-driven fluid simulation in a manner that allowed for a more sophisticated effect – with efficient turnaround – than out-of-the-box simulations would allow.
While Stardust’s material leant itself to VFX it was a diverse project in terms of content, leading to many ‘one-off’ visual effects and meant that nothing was predictable.
Chiang says: “It’s an amazing, magical, fantastical film. The design reflects the simplistic environment and a combination of the simplistic approach combined with the sophistication of the VFX toolbox creates a really exciting combination.
Matthew [Vaughn] always thought hard about the look of what he wanted, identifying the bare roots that would support the narrative. This was very liberating in a way and makes you think of the effects very differently.”
A walk in the clouds
All the clouds were rendered in Double Negative’s Voxel Rendering System. Clouds were constructed by the cloud team, under the supervision of 3D technical supervisor, Gavin Graham, who says: “The environment shots travel over a huge distance and needed to kept photo-real.
TECTO and dnCloud were both modified since their first outing on the World War I aerial film, Flyboys, which Double Negative had worked on the year before.
“The additional functionalities were a huge step forward. The Stardust environments covered huge distances that required a much greater volume and diversity of clouds.
This demanded a library that needed to be extensive but also flexible, including clouds that could be made up of three to ten ‘cloudlets’, allowing the shape to be modified on demand.”
Because the storm clouds required more sophistication, they were created from greater numbers of smaller particle clumps that continuously rolled, expanded and moved independently, work that was carried out by dynamics technical director Nicholas New.
Lindahl says: “Previously, the clouds were out of a box and couldn’t do much. The modifications made for Stardust meant that the clouds could be rendered out on different channels, which allowed the compositor to grade them according to the requirements of the shot. Daytime to night-time, overcast or bright sunshine – all the tools were there, so that the artist could do what they needed.”
Other Double Negative proprietary software, dnCloud and gtoMunge, were also used, providing the artist a means to preview the clouds at low resolutions inside of Maya, so they could work on layout in real time.
The hardest challenge – the creation of the Sky Vessel – saw a wooden model be replaced by a fully realized CG model in key scenes.
The Double Negative team had to create extensive CG environments of the kingdom of Stormhold that formed the backdrop to exterior Sky Vessel sequences.
Now that’s magic
Some scenes called for the creation of signature magic effects from the evil witches – the green effect here was a combination of photographic elements and CG particle effects, plus softbody ‘ribbons’.
The final composite scene shows the placed mountains, atmospherics, and solar effects.
Project: Visual effects for Stardust
Client: Paramount Pictures
Studios: Double Negative
Software: Double Negative(dn), STIG, dnPhotofit, dnPlaneit, dnRendering System, dnCloud, gtoMunge, Autodesk Maya