‘John Carter of Mars’ is the largest creature project Double Negative has ever undertaken, requiring two and a half years of work. Updating the facility’s pipeline to meet the demand resulted in an exciting new Creature FX division.

Double Negativestarted working on JCM during pre-production in May 2009. Principle photography began in January 2010 and after a six month shoot, their team began on post production, continuing from June 2010 all the way through to December 2011, under VFX Supervisor Peter Chiang.

The artists created nearly all the movie’s creatures plus a selection of environments, all of which needed to coordinate with the work of Cinesite, the facility responsible for the majority of the project’s CG sets, and the live action. The Utah desert, wide open, barren country under dazzling bright sunlight, was the shoot location chosen to represent the Martian landscape.

Touching Down on Mars
The Double Negative team’s work began with extensive on set data capture including HDRI using a Spheron Spherocam HDR, and photographic stills for texture and photogrammetry. “We had witness cameras to aid tracking and used a Leica HDS6200 for laser scanning. We also shot helicopter plates and photographs for image based modelling to recreate the terrain and geology for certain locations,” said Peter. “Our team and Cinesite’s shared a lot of geometry and textures, and all the on set data was compiled into a database for easy access.”

The team’s detailed on-set data capture would not only be required for accurate tracking and placement of their creatures into the live action. They were also asked to create some of the especially creature-heavy environments in the film - the White Ape arena, internal views of the Thark’s city and exteriors for the Temple of Iss.

Peter explained that Andrew always wanted to use as much of the real environment as possible. “The set extensions enhanced what was already present in the locations’ structure and geology. He wanted to evoke a past civilisation and that we were seeing the remnants of much grander scale. Concept artist Ryan Church and production designer Nathan Crowley had produced a library of beautiful images covering all the major sets. The location scouts were actually done after we joined the project, so we developed the looks further as we went along.

Finished Image
“We also worked very closely with DP Dan Mindel on the whole show. We would talk at length about lighting and atmosphere so we could extract the most information from each set-up during the shoot. We were always conscious of the finished image allowing space and composition so that when all the elements had been added it still retained his photographic style.”

In the pipeline, Maya was used as the foundation for all modelling, and for rigging and animating the creatures, with numerous proprietary plug-ins and pipeline tools built around it. All the costume and fur dynamics were handled through a combination of Maya and Houdini.

John-carter-mars-3 John-carter-mars-4  
By the time Double Negative joined the film, Legacy had spent a year designing the creatures with director Andrew Stanton, and could provide Double Negative with ZBrush models to help start building their CG creatures. As well as the high level of believability the director expected, what made the creatures for this movie challenging is the amount of screen time they have, numbers of them within the frame, closeness to camera, and the range of actions in their performances. They also required complex interactions with practical and CG sets, and with CG and real characters.

Martian Tribe
“Andrew Stanton always described the Tharks as a nomadic, Masai warrior type tribe, but with the raw aggressive nature of Vikings,” said Peter Chiang. “The dry, arid, sun-bleached atmosphere affected their look. We made several refinements to the design once we started, based on look development and animation studies. Andrew wanted them to feel more human to help translate the actors’ performances captured on set. He also wanted to direct the performance closely, so we developed a facial capture system and also made minor alterations to the eyes and muscle structure. The eyes originally had black sclera but we made them white like humans’ eyes for a better expressive read.”

Co-Animation Supervisor Steve Aplin described creating a back story for the Tharks as a tribe. “We began in pre-production by creating a number of vignettes about how Thark day to day life might look if a nature documentary camera crew were to come across the Tharks by accident and wanted to observe their behaviour,” he said. “We looked at documentary footage of African tribes, such as the Dassanech and Massai, as well as more brutal cultural reference depicted in Viking films. Andrew was always pushing the energy of these characters, and how quickly they could transition from stoic, Clint Eastwood type personalities to ruthless, deadly machines in a split second.

Although similar to people, the Tharks are very tall, have two sets of arms, no nose and external bones curving around their faces. Nevertheless, they were always regarded as characters that needed to deliver a specific performance. The animation team, led by Steve and his co-animation supervisor Eamonn Butler, worked hard with Andrew to convey this feeling. Early studies established a lot of the character traits and this led the requirements for the look development.

Skin Deep
Once animation tests began, the Tharks’ key muscle groups were brought back closer to the moves of their human counterparts for the natural mechanics to work convincingly. It was important for the principle Thark characters to stand out from the crowds of other Tharks. All the females had face paint and wider hips, for example, and older Tharks tended to be more blue-green, but a tonal approach was always used to create more depth in the skin. The heroes’ costumes received more work, but any Thark moving close to camera needed high detail.

These creatures’ textures were incredibly detailed. The artists began with high resolution images, separating them out into different layers and adding bespoke painting to give unique detail to each individual Thark. Texturing was done with a combination of Bodypaint, Photoshop and Mari.  The harsh desert light made it harder to balance the specular values of the skin and differentiate this from the moisture and sweat on the Tharks while keeping them dry and sun blasted.

Eye to Eye
Tracking and compositing the CG Tharks into the shots and making them look convincing standing next to the real actors was one of the biggest challenges in the film. Most of the tracking was handled using Double Negative's proprietary PhotoFit software, and all compositing in Nuke. “We always started with the actors who played the part of the Tharks in shot, rehearsing the action until Andrew was happy,” Peter said. “We tried to use the take with Carter, without the Thark actors, as the chosen plate so we could minimise clean up. This meant adding all the shadows and light interaction back onto Carter once we had an approved animation.

“The Thark actors were always shot with the correct eye line either on stilts, on boxes or decking or walking around with a backpack with a Thark head at the correct height for the character. We also had to prevent the very tall Tharks from overwhelming the hero John Carter and reducing his impact in scenes. Fortunately, Andrew’s eye for composition and staging helped with effective layouts for the shots.”

Once they had viewed a rough cut of the film they were able to determine the level of detail we needed for the Tharks close up. The lighting started with the HDRI but they soon found additional tweaks were needed to emphasise the geometry and highlight narrative aspects in the shot. Lighting and rendering relied on a proprietary system built around both Maya and Pixar's RenderMan.

Performance Ready
The body motion of the principal Tharks was primarily keyframe animated, with the facial performance consisting of a combination of motion capture with keyframe enhancement layered on top. Steve said, “Due to the sheer volume of animation cycles required, we relied more on motion capture to flesh out our crowd system. The capture was done both at Centroid on their optical system and by using an inertia Moven suit. The creatures Woola and the Thoats were keyframed. We explored using motion captured camel data as the base for the Thoats’ movement, but it turned out to be too erratic to cover all the necessary actions.

“Andrew was very clear from the get-go that the Tharks had to stand next to the live action actors and be inseparable in their level of realism - they had to be able to hold their own. He also wanted a very tangible connection between the digital and live action worlds, which is why he was keen to have the Thark actors on set, acting with the live action actors with their eyes at the same height as their digital replacements.”

Layered Crowd
When the Tharks appear in the film’s huge crowd scenes, a three-layer approach was required, based on an animation library consisting of more than 800 unique pieces of animation supervised by animator Stephen Enticott. The first layer consisted of two or three hero rows of Tharks closest to camera. Their performance was hand animated, giving Andrew the flexibility to direct the foreground action. The next layer was for mid ground action, which the animators hand-placed using the library cycles, while composing the shot to draw the viewer’s eye around the frame as the director needed.

The final, third layer covers all distant Tharks and involved the greatest numbers, under the banner of Crowd Simulation supervised by Eugénie von Tunzelmann, FX Supervisor and crowd specialist. “She and her team used the animation library to populate vast areas of the background via a proprietary particle instancing tool through Houdini,” Steve explained. “They could digitally airbrush an area with particles, replaced with animation at render time, and blended different pre-animated sections of motion together to maintain richness and complexity in the backgrounds.”

“We shot several motion capture sessions with performers we had auditioned for various Thark attributes. Some had specific attitudes we keyed into, some were physically similar in build, and some were more athletic. A good combination of the three was actually discovered in one of our lead animators Thomas Ward. When applied to a Thark, his motions were solid fit and great starting points for many of our cycles.

Facial Performance
Motion capture was also the basis of the facial animation in most shots, producing a very natural looking performance to build on. Eye motion was entirely keyframed, using either the Thark performers' footage or additional animator shot footage as reference. A lot of attention was paid to the eyes because they had to hold numerous subtle, complex emotions in some extreme close-ups. The animators could layer on top of raw motion capture to accentuate, clean up or rework a performance, as needed.

Steve noted that the centre of the Tharks' faces were an issue from the start. “The nose on a human face is such a visual anchor. Without one, we asked the question - what do we feel the underlying anatomical structure would be, and how can we accentuate it to achieve the feel of a nose being there? We came up with a series of muscles and tendons which we could fire quickly before key mouth shapes were dialled in, as well as tying the eyes and mouth together via the nasal labial folds to avoid a dead area in the space between.

“In addition, the nostrils on the Tharks were actually on top of their heads, so we ensured that they performed in conjunction with the rest of the face to reflect what regular nostrils would do. It's a small detail that most people won't even notice, but it would take away from the performance if they weren't there. Finally, we layered facial skin simulations on top of everything to tie all the relative areas of the face together, and give the skin additional secondary jiggle that really paid off in those extreme close ups.”

The Tharks each have two pairs of arms as well, posing a different kind of challenge. While Andrew didn't want the arms to act independently as if the Tharks had two brains working toward different ideas, 'twinning' the actions gave an automated feel to the performance. “We chose the upper set of arms as the primary action tools, and worked in the secondary lower set to support them. At times his meant introducing a partial twinning, offset enough to not be distracting.

New Creature FX Team
Because the Martian creatures are not hairy or furry, skin and muscle were important to get looking right. “The muscle system gave us the generic bulges in the right place but a further layer of displacements added the shape detail. Skin sliding, tendons, folding skin and bone pressure changing the skin colour were all part of the tool set developed for the film in ‘Creature FX’”, Peter said.

Creature FX at Double Negative is a relatively new discipline within the realm of creature work. It was developed during John Carter to bridge the gap between the mesh centric world of rigging, and lighting and rendering. Creature FX supervisor Richard Clark explained that traditionally, creature TDs and riggers focus on making the mesh represent as much of the anatomical detail as possible and can animate, deform and drive the mesh in many ways. “While this approach has benefits, the artists can never use a mesh matching the level of detail seen in a ZBrush sculpt,” he said.

“Sculptors and lighting artists have the opposite problem, as their disciplines are not animation centric. They can achieve almost limitless levels of detail, but virtually have no way to breath life into that detail. To get the best of both worlds we have developed a new discipline that plays on the strengths of each one. Creature FX artists are essentially creature TDs, but work with lighting and renders to turn those amazing details into something that moves and compliments the character animation work.”

Flexing Muscles
As the Tharks are lean and muscular, every muscle had to be animated to support the whole performance. This involved developing a new tool for Maya called dnBeouf that communicates with rigs and renders and provides an animation interface giving feedback in hardware. They dissected every ZBrush anatomy sculpt to provide ‘areas’ to drive on the displacement map.

dnBeouf also drove mesh deformations such as muscle flexing on the rig, tendon deformation, dynamic wrinkles, skin sliding and compression data for skin colour changes. Richard said, “This gave us near real-time feedback for key framing to the performance. The result was viewed in the render to asses it with impact of lighting. Once approved a mesh cache was delivered to the lighting team to render for the final.”

Man’s Best Friend
Woola, John Carter’s loyal companion and protector, was possibly the most fun creature, similar to a dog combining a fairly grotesque design with endearing performances. Mysteriously, although his build is fat and stubby, he is able to move at heroic speeds over most terrains.

Steve agreed that he doesn’t have the most instantly appealing face. “We started out by making his movement pretty cartoony and extreme, but in one of the first sequences we animated we found that by having Woola do less and appear more vacant and attentive to Carter’s every move, he became far more lovable. The lead animator for Woola, Craig Bardsley, focused his team on reference of bull dogs, pugs and boxers for locomotion and character traits. They spent a lot of time exploring how a creature of 400lbs could move at speeds up to 200mph, yet stop on a dime. By displacing his weight in number of creative ways they managed to avoid letting him feel like a Tex Avery cartoon.

“For the head animation, Andrew always reminded us that you should be able to gain a performance for him by keying off something as simple as a sock puppet. If you could make a sock puppet emote, Woola would be similarly effective. Such behaviour as the way a dog tilts its head while trying to understand its owner’s words really embellished Woola’s character. His tongue was also fun to animate, based on a dog’s tongue. Effects artists were able to add a separate layer of jiggle motion over the top of the key frame animation to really amp up the fleshy feel of the tongue motion, especially on the thinner edges surrounding it.”

Desert Transport
The Tharks ride massive, eight-legged beasts over the vast distances across their desert environment, calling for such reference as elephants, rhinos, horses and even camels at one point, as mentioned earlier. The heavy design of the Thoats' eight legs and their close proximity presented the animators with some difficult pose massaging and the need to play with the timing of the motion to avoid heavy intersections, especially when galloping. Due to its incredible size, the tail of the Thoats was played as if it had strong cartilage running through it to support its weight, but with minimal flex.

On set, the actors rode on motorized Thoat rigs that created saddle motion derived from the animation cycles. Steve said, “Once the Thoat team had animated various walks, canters and gallops and recorded the degrees of rotation and levels of translation of the CG saddle on them, special effects supervisor Chris Corbold and his team used these to build and drive the movement of the live action saddles on set, giving the actors the correct motion for the animators to use later on the CG Thoats superimposed underneath.

Because no motion capture was recorded on set, the Tharks were actually more forgiving because we could adjust their motion more easily to fit them to the Thoats.

Ape Interaction
At a high point in the action, John Carter is thrown into an arena with one of Mars’ most vicious creatures, the gigantic White Apes. They also posed a keen challenge for the creature and animation teams. According to Steve Aplin, “The White Apes had to be insanely physical and interact seamlessly with the environment, John Carter and the chains he wielded.”


Andrew's concept department had already heavily designed the Apes before production began, which needed only slight alteration during the animation test phase to accommodate a more expressive range of motion. Their lead animator Ben Forster had his team looking at silverback gorillas in particular for natural motion to key from. As they were at least ten times bigger than the average real ape, additional weight passes were added and their ferocity was cranked up to the next level.

Steve said, “We struck a careful balance between the speed the Apes had to move about the arena and maintaining the sense of extreme weight. They are also blind and seek Carter out by their sense of smell, so this had to be worked into their performance as well, in a way that the viewer would immediately understand.”
Words: Adriene Hurst
Images: Courtesy of Walt Disney Studios