Method Unravels the Maze with a New Creature Pipeline

“Method deliberately began seeking out artists with the right experience for the job, and once I came on board we contactedErik de Boerwho had been animation director on ‘Life of Pi’ with Rhythm & Hues,James Jacobsfrom Weta Digital and others. It was the first time we had all worked together before, but each artist had a lot of experience.”

Surrounded

The producers were enthusiastic about the team, but wanted to see a completely modelled, fully rigged and animated Griever by the end of the shoot, which was only to last nine or ten weeks. For this reason, Sue moved between the set and the studio during filming while her co-VFX supervisorEric Brevigstayed out at the location for the duration.  The shoot took place in and around Baton Rouge, Louisiana, where one of the challenges was the need to use blue and green screen extensively and very flexibly.

In this story, a group of boys have been pulled from their homes and their memories erased. They must live together as a community, trapped at the centre of a huge, stone Maze. Deep inside this Maze, the Grievers live.

“We were outdoors in all weather, and inside a stage that was a maximum of 24ft high to represent an environment surrounded by the massive walls of the Maze, which was to stand 100ft high,” Sue said. “Using blue and green screen across varied conditions while optimising the cost, time and situation, takes a fair amount of skill. The set could only be built up to about 16ft, which meant the lighting on the walls was compromised. We couldn’t capture any of the long, crawling shadows to help build the drama, for example, which put some pressure both on the DP and on our team later in post.”

One of the primary sets is the Glade in the middle of the Maze where the boys are living. The set was an open field, and the crew operated from the middle with a 16ft set piece of the wall positioned about 300ft away. The field was actually already surrounded by trees, so the team used these as a rough guide and replaced them with their CG walls, handled in some shots with blue screen and in others with rotoscoping.

Living Walls

“Lighting the walls correctly was crucial for realism and continuity. We had to think like cinematographers and use the story for our cues. For example, these walls open each day at sunrise and sunset, which made two ideal lighting cues for the lighters. We placed long shafts of light glancing down the walls’ surface whenever it was suitable, which also helped enhance the scale,” Sue said. Due to its importance for drama as well as realism, she and the team had to look at lighting from both a physically correct point of view, and from an artistic point of view to include expectations and assumptions relating to the story.

While the walls were a fairly straightforward build in Maya and textured in MARI, a major technical challenge was the growth of ivy that covered them. Any CG ivy needed to match the practical props provided at the base of the walls, which Method’s team extended digitally up to the top of the walls. “We had several different factors to consider before deciding on our approach to it. Trying to populate the environment with enough geometry would have been time-consuming, very difficult to light and render, and not very flexible,” Sue explained.

“Our team decided to grow the ivy procedurally by writing their own software in Houdini,” said Sue. “They could draw ‘edges’ onto the walls indicating the location of growth and then specify the number of branches for it to split into, the density in different parts of the frame to coordinate with shafts of light – and so on. As a procedural process, it was controllable and replicated quickly, and resulted in a lot less geometry for us to manage, and we could adjust the level of detail according to the proximity of the camera in different shots after the shoot, without limiting the director’s and DP’s decisions on set.”

To avoid creating shots that combined assets lit and rendered both in Mantra and in V-Ray, the artists exported much of their Houdini work using a script they had written to make it possible to render Houdini output in V-Ray. In one such scene a Griever tumbles down from where it is lurking on a wall, bringing lots of the ivy down with it. Because the ivy had been generated in Houdini and rendered in Mantra, while the Griever was built in Maya and lit in V-Ray, the ivy was exported from Houdini using their script and all of the CG could be rendered in V-Ray.

Controlling Forces

‘The Maze Runner’ is director Wes Ball’s first feature film. He is known mainly for his work as a graphic artist, visual effects artist and short film director. For an exciting, fast-paced sequence in which the heroes Thomas and Minho race through the Maze as its huge walls shift violently around them, threatening to seal them inside, Wes supplied some of his own previs to show his ideas about the action and the movements of the walls. Previs was essential to prevent high-action sequences like this from falling into chaos. With the team’s input, the sequence soon developed from sliding and rotating motions, to walls tumbling down, a ravine opening and clouds of dust flying up.

“Taking cues from real world destruction, from earthquakes to collapsing buildings, the final look was achieved with multiple layers in Houdini, starting with a ‘crack’, then fine powder rising up resembling hydraulic air escaping, followed by sandy fragments, small stones – and then huge rocks breaking away and falling around the boys,” Sue described.

“This shoot took place at a car park and involved a 40ft high green screen, 180ft long, that had to withstand the Louisiana winds and heat. The previs was followed by techvis to make sure that what happened on set would make it feasible to produce the desired results in post. Eric and I would review the shots in advance of shooting to plan the set-ups – for example, we might need a Technocrane for a particular scene and have to determine how it should be used. With the previs and techvis in hand, we captured the action and from there, the editor could cut and manipulate the footage to build the story and drama.”

Heart of the Action

The Grievers are at the heart of this story, creating fear and tension, and were the focus of Method’s work. Their essential nature is a deadly, six-legged mash-up of heavy machinery with organic parts.Erik de Boerjoined Method to work on this project as animation director just after the team received concepts for the Grievers from concept artistKen Barthelmy. “They were inspiring sketches for us – very dynamic poses of a mechanical-organic creature. The shoot still hadn’t got underway but we needed to determine the size relative to the characters in advance, and start on the build,” Erik said.

Sue had read James Dashner’s book ‘The Maze Runner’, on which this film is based, before starting to work on the movie, and as she, Eric and Erik discussed looks for the creature, they realised the author concentrated mainly on the characters’ reaction to it, without supplying detailed, graphic descriptions. In terms of looks, they didn’t need to stray too far from Ken’s concepts.

Sue said, “To develop the Grievers enough to build and animate them, we decided to look at reference of cranes and pneumatic drills. The animation was going to be tricky, partly because their large, heavy bodies needed to move with speed and agility along the narrow corridors of the Maze. The corridors were only 8 to 12 feet wide but their legs could actually splay 15ft apart. We introduced a kind of hydraulic, telescoping mechanism so the legs could extend or shrink as they ran along to accommodate the available space.”

Hydraulics and Pneumatics

“Once you move into 3D, you can experiment with the design and specific details. For example, we designed a special mechanism for each joint, offsetting the pivot points to make the motion more distinctive,” said Erik de Boer. “It was also at this stage that we developed the telescoping legs, so they could gallop out across the Glade area as well as negotiate the constricted Maze corridors.

“We had lots of actuators, or small motors, controlling the movement of those legs, and imagined that the organic heart was pumping the hydraulic fluids directly into the legs via many complex hoses attached to the body. The lungs also would be driving the pneumatic jackhammers at the termination of each leg. Along the long legs were four articulated joints that we could impose limits on, and force the solve for certain poses to avoid intersections.”

Overall, they wanted to design an interesting silhouette to work from, adding hydraulic hoses swinging from its back and, running down its spine toward its metal tail, a line of tiny knives that flick up and down, catching the light. The riggerVictor Barbosadevised a procedural zipper-like method to control those knives that sourced pre-made, keyframed motions. This gave it a centipede feel and allowed the animators to express emotion by drawing in or expanding the Griever’s pincer-like tail.

Organic Machinery

They always looked for a clear, graphical quality in all the poses and watched how the design came across on screen. Including strong negative space helped the viewer understand how they were built. Erik said, “Visually, of course, these inner mechanical stories are still concealed except for the hoses, which tensed up at the moment the actuators kicked in and the legs fired. We tried to sell its mechanics in that way. Our idea for the jackhammers was that they helped the Grievers grasp onto the rock walls and floor – causing the falling leaves and crumbling walls whenever they contacted the set, improving the integration.”

“For the organic, fleshy parts, I focussed on anything that freaked me out – macro photography I found of bed bugs and fleas, slug skin and warty toads – for inspiration,” said Sue. “Erik also thought of the Grievers experientially, even imagining the sound effects for the metal legs and hydraulic breathing system.”

Erik was especially interested in mixing machine moves with organic motion. “As much as the dynamic concept drawings, instinct tells you that these will be very dynamic creatures,” he said. ”We started looking for the conventional sorts of reference from nature – ants, cockroaches, centipedes and other creepy crawlies but the result was too insect-like. So we also turned to hexapods and similar six-footed machines, layering in that awkwardness as far as possible, even slight clumsiness to give the kids some hope of somehow overcoming them.

“Nevertheless, they are well-adapted to the Maze environment and had to be agile enough to pose a threat, move at speed and climb walls. AnimatorStephen Cleedevoted a lot of R&D work to figuring out how these creatures locomote. It was a fun, inner conflict to engineer!”

Creature Team

Sue relied on the creature effects team to visualise all her ideas - the Griever’s heaving chest for example, the scales over its underbelly, and the quivering layer of fat over its back. The secondary jiggle associated with soft tissues usually needs a secondary simulation, resulting from acceleration and deceleration, layered on top of motion to make it more believable. All of these required simulations.

Creature supervisor James Jacobs helped avoid having to hand-animate many such effects through his work on Method’s creature pipeline. A finite element solver was written and used with deformers to define the tissue deformation and how the skin should move. “Traditionally, you might hand animate movement in the surface of the skin by blending shapes and adjusting vertices. Instead, the solver and deformer employed parameters for warp, wobble and fat dynamics. It lessened the work for the animators and made the pipeline more efficient,” Sue said.

James’ understanding of weight displacement and fat in motion actually earned him a Scientific and Technical Award from the Academy of Motion Picture Arts and Sciences for his work on the Gobelin King in ‘The Hobbit’ films. He has continued to help Method’s team build other creatures for the upcoming film, ‘Night at the Museum’.

Weight and Speed

The Grievers’ weight and speed were two characteristics the team worked on quite hard. The creatures had to feel massive and heavy to the audience to make them seem more dangerous, but also move as fast as or faster than Thomas and his friends.

Erik said, “Expressing the weightiness he wanted meant giving the weight time to get up to speed and then resolve itself when it stops. It’s trickier with a six-legged creature because it has more ground contact and will always have a valid 3-point support. Such creatures tend to shuffle or bounce about - by the time the body has responded, the legs are into the next stride. Finding a satisfying cadence with a biped or quadruped is actually easier. We also played with options for external forces to interact with the Grievers to help sell that weight, bumping against walls, striking props with its tail, anything to establish connection.”

Thus when they skid around corners, brush up against the ivy or impact with the walls and floor, they cause damage such as falling leaves and crumbling rock. People are intuitively aware of how objects of different weights and materials interact – they might not notice the subtle impact effects but would miss them if they had been left out.

Jumping from Set to Animation

The group of kids’ final attack on the Grievers was an interesting challenge, partly because it was a high action sequence shot entirely on a blue screen stage. Stunt actors in blue, brandishing blue sticks stood in for the creatures, a 360° blue screen encircled the stage, and only the floor and the actors are captured in camera. As the kids enter the space the Grievers turn and try to attack them. But the boys fight back.

Wes Ball, as an animator and VFX artist himself, understood the potential challenges for the animation later. Normally a fairly calm person, when explaining the Grievers’ viciousness he gave a full-on performance, screaming and flailing his arms, to demonstrate to the team what he was after in the shots.

Sue said, “At first the young actors were hesitant but once the director got them going, a series of great fight performances were captured. The animators worked hand-in-hand with the editors in post to produce the exciting battle sequence. Using animated CG to make the best of the fight moves work, they applied some reverse engineering to make animation play off the live action performances.”

Quality of Motion

Erik had joined Method specifically to work on this project, and found it exciting to return to off-the-shelf software and work on tools alongside a very competent team of animators. But in fact, one of the first changes they made was to the workflow – specifically, they would let the animators indicate their work preferences for improving the quality of motion on a character, create a fast way to share their work, put it into a cut, watch it in sequence, evaluate, come back with a fresh eye - and iterate.

Erik said, “Regarding the pipeline, fortunately, animation remains an island in some ways within the rest of a facility’s pipe, with fewer dependencies on other departments. Victor Barbosa, the rigger, built a powerful and intuitive rig that drove the complex telescoping legs on the Grievers, fully functional with IK/FK switching. It was a great way to switch to different levels of detail. Another of the creature artistsPaul Jordandid excellent simulations on the hoses and other effects.

“James Jacobs’ proprietary tools moved the Grievers smoothly through the pipeline and ran the many simulations. Doing that allowed quicker model updates – we could re-run the simulations fast and return the frames to the render farm. We became pretty efficient.”

Animating to Camera

Erik always aims to go on set on projects, finding it is vital to keeping CG animations aware of the context and fitting them into the full production. “On set, we have the chance to think about giving the camera the appropriate level of energy, making the framing and composition suitable for compositing the creatures in. In Baton Rouge, I was observing how the production managed this large group of young actors, energetically fending off the stunt team,” he said.

“In post we went on to add overriding camera moves and so on to make sure the camera followed not only live action characters but also the CG Grievers when they came galloping into view and collided with the kids. You always have believability issues with blue screen shots especially, but having been on set gives you more cinematic freedom to design your camera takeovers and extra CG shots to really convey the feeling that the cameraman was out there with the monsters - and vice-versa.” www.methodstudios.com

Words: Adriene Hurst
Images: Courtesy of 20th Century Fox