Prometheus - Highway to the Stars

VFX Supervisor Paul Butterworth, leading the VFX team at Fuel, described the process of finding references and inspiration for the Orrery, a holographic three-dimensional mapping system the story’s astronauts discover on the alien planet. An orrery as a device is not new and, in fact, an image that the director Ridley Scott chose as a key reference was an 18th century painting called ‘A Philosopher Lecturing on the Orrery’. However, the ideas and concepts for the Engineer’s Orrery in ‘Prometheus’ had to be flung far into the future.

Guiding Light
Paul and the team started researching the Orrery not long after he and the Fuel VFX team worked on the Rainbow Bridge effects for ‘Thor’. “That previous project had involved studying astronomical phenomena as well, like worm holes, star clusters and nebulae,” said Paul. “I’ve always been a fan of Hubble space photography and the models now used to depict the construction of the universe. The Art Department at Fuel also cultivates unusual geometric patterns, textures and sketches for inspiration. So much beautiful space imagery is available to anyone now from NASA, and that became our principle guiding light.”

For a starting point to the three-dimensional design and build, another set of references was sourced and shown to Ridley for his reactions and preferences – sculpture, classical paintings, even sounds and movie clips. The painting mentioned was among them, for example, showing mechanical hoops circling the sun to representing orbits reaching out into the universe. “Ridley’s concept called for a core at the centre, casting out light, as the place and time the Big Bang had occurred and scattered millions of tiny objects out in all directions,” Paul said.

“That central location also acts like a magnifying bubble. The user might grab something from the surrounding space, holding every star and celestial body ever made, and as he moves it to the centre, it would be magnified, like moving your mouse over the Apple dock on a Mac computer. The user could then study this object under a volumetric lens.

Orrery Story
“Further to this, Ridley liked the idea of frog spawn. When you switch on the Orrery machine you are presented with the entire universe, but around it you might have a selection of star systems of personal interest. Notes like this were story points for us to keep in mind as we worked on it. A final point was that in the end, the Engineers had triggered a switch firing a targeting system focused on one element at the centre. On investigation, this was a planet – Earth.”

From these essential story ideas they developed the looks based on real nebulae and astronomical objects. Lead effects TD Roy Malhi developed a set-up and wrote several specific tools for simulating gassy clouds and embedding stars within those clouds that illuminated them. Fuel’s Art Department typically works alongside the effects artists, who can run tests as they work to show the art team, who then produce further artwork.

Genetic Code
Meanwhile, animations for the Orrery’s hoops in motion were started. Its main concept artist Luke Bubb painted numerous style frames to design what viewers would actually see. How many stars, elements and systems would be visible? Would we see the hoops running around it literally holding the planets in place - or not? One of Paul’s ideas was that the hoops could represent genetic code, so that by invoking a particular planet, for example, a hoop would span out made of millions of tiny blocks, each one depicting genetic material.

“We based the idea on the Engineers’ interest in producing new species on various planets,” Paul said. “These elements - hoops and their ‘DNA’, nebulae, gas with the basic light set ups from the centre out - were the guiding features that compositing sequence supervisor Denis Scolar used to bring the complete machine together. It was built as an immersive, stereoscopic, experiential object and therefore, I designed it much more densely than I would for a mono project. Knowing the audience could use that extra dimension to see and understand the Orrery was exciting.

“I really enjoyed it as a creative artist. My background is in design and illustration as well as live action photography and direction. Art direction was a major factor in developing the Orrery. We watched the shots in stereo many times over to plan every movement, not just up, down and across but objects passing in front of others, interacting or moving into the background.”

Deep Image Tools
Roy Malhi’s tools for the gas formations, geodesic dome system with animated surfaces and connectors had all been developed in Maya. The hoops of genetic material were all set up and generated in Houdini. This meant sharing set ups and combining them. To manage the rendering and allow the renderers to interact, a system of deep image tools was employed. “When you render an element in a conventional project, the result is a flat image that you then combine with other images, shadows and interactions in compositing to give the illusion of 3D,” explained Paul.

“In a deep image system, your working environment is more like a cloud. You have access to all pixels, right back into the depth of the image as well as across it. You can then combine the render ‘clouds’ rather than confining the elements to a flat plane. Creatively, you can sign off the different elements at an early stage. As the overall project progresses, instead of locking off the final product and rendering whole shots, you can render one portion of your work at a time - in our case, the Engineers, the star formations, hoops and so on.”

The principle advantage to this system was the ability to lock off rendered sections of this massive Orrery object - containing nearly one million polygons - as they went. A further advantage the team found was using elements rendered in one package to light those rendered in another.

Compositing Challenges
Paul said, “However, this level of artistic control and flexibility comes at a cost. The process is very heavy on disk space. But it was worth it for the opportunities it gave us. As an example, if we had a gassy cloud and wanted to have a ship flying through it, normally we would render the cloud and use a hold-out matte for the ship inside it. If later on the ship’s animation had to be edited, the cloud would have to be rendered as well.

“The deep image system means you can render the gas cloud as required, then continue changing the ship animation and re-rendering only those elements, independent of the rest. As well as the designer, this set-up benefits the compositor, who has the freedom to manipulate details like camera effects, also independently of the rest of the render.”

Fuel VFX submitted all shots to the production in stereo. The earliest concepts were mono but the team would begin planning for the 3D composition as soon as possible, because shots usually needed to be designed more densely than normal, like the Orrery. Paul said that balancing stereo compositions can be a challenge, and the team sometimes changed their compositing style in order to keep enough visual interest in the shots.

Rotomation vs Mocap
When planning the animations of the holographic representations of the Engineers, the two sequences were approached in a slightly different way. On the bridge of the Juggernaut, when we see the Orrery and the Engineers manipulating the controls, the live actors were shot in prosthetic suits – either with or without a clean plate. Fuel would then paint these figures out, replace them with their models and rotomate, or match very precisely, their performance in the frame. The director could still maintain control over the performance, cut the sequence together as required, and rely on the accuracy of the rotomation to keep the sequence intact.

“It proved to be a very elegant way to work. It’s still hard work, requiring accuracy and retention form the animator, a but a great way to get performance sign-off especially when the director is not confident about including an animated character in a live action film,” said Paul.

The first appearance of the holographic Engineers takes place within the pyramid as the characters run along a dark corridor. The very low light and unevenness of the floor interfered with the actors’ performance. “In this case we decided to use a 3D scan of each actor in his gear and built a detailed rig for him. The rig was then passed to a motion capture company in London, where they captured the actor’s performance in a more controlled, directable environment. This capture data was sent back to Fuel to apply to their rig and virtual character.”

Ghosts of Engineers
However, having the scan, rig and performance data still left the challenge of the viewer’s concept of what this sketchy, tenuous, luminous character might be, or be doing. This presented another design and refining process that continued till the end. The brief they worked from called for figures you might see in volumetric security recordings of a time, perhaps thousands or millions of years ago, similar to security footage revealing random day-to-day activities in an office building.

“But in this sophisticated, alien version, the walls of the building were projecting a 3 dimensional version of the characters that a viewer could see from multiple angles - and even fast forward, stop or reverse. Ridley also liked the notion of making the characters perform in ways that would suggest interesting possibilities to the audience,” he said.

“For the look of the images, we deteriorated the model to give it a look resembling a broken TV image, showing various kinds of image degradation from missing sections and random bands of deterioration, to ‘dead pixels’ on a monitor. We tried to mix the familiar and scientific with the alien and fantastic.”

Interactive light was an essential part of all of Fuel’s holographics. While this is a typical part of visual effects work, in stereo , the accuracy and completeness of the CG surfaces they generated for their lights all had to be perfect. Paul said, “We underestimated the effort required to line up shot for shot, pixel for pixel, the geometry in the caves, the Orrery, or on the control desk. In the case of the desk for example with its green energy effects, we weren’t building just one desk but a unique desk for every shot.”

Fortunately they did have accurate LIDAR scans, survey data and drawings of all sets but it still became a huge task to re-model these surfaces perfectly for the Maya or Houdini lighting environment. When Paul had been on set for the key sequences, he had also simply walked through and around the set to get a feeling for relative positions of objects and where interactive lights would be important for realism.

Cartographic Kit
A major task the astronauts tackle as soon as they arrive at the alien domes, or pyramids, is a mapping and survey operation of the exterior and interior structure. The design of the Holotable and mapping system on board the Prometheus and the handheld scanning probes called survey pups were still an unknown quantity when Fuel VFX started on the project. “The production knew where the table should sit within the Prometheus set and what it should be able to do, but not its form,” said Paul.

“The sets of the ship interior were beautiful to work with. Our initial brief and concept frame was pretty interesting – we knew the table would have a glass surface and could volumetrically project a map using survey data. We also knew there were probes that flew around inside the aliens’ buildings and as the devices scanned, they send data back to the table, interactively building a 3D map. But we had no idea yet what those buildings, the maps, the devices or the table looked like.”

This prompted another quantity of concept frames to develop looks – should the map resemble an ant farm design? Would the alien pyramid itself have four walls or was it more of a dome? If it was a mountain-like structure, how far was it buried into the ground? “In short, the design had to answer a lot of structural questions. Inspired by the looks of laser and LIDAR scanning techniques, we decided that the mapping system would represent data scanned directly from the ship with the blue surfaces the viewer sees on the table, and derive the internal structures – tunnels and corridors from the probes – with other colours.

Holotable Hub
“During the film we see this 3D map grow and evolve as the survey data returns to the Holotable to be processed, revealing the tunnels, rooms and laboratories. We provided numerous frames and motion tests that Ridley really responded to, deciding to make the table a larger, more prominent feature of the story. The original shot count of 15 or 20 suddenly doubled,” Paul explained.

“Because the casts’ eyelines were working in different directions, I designed several different parts of the interface based on ideas from modern aircraft systems but projected into a futuristic technology – instead of altimeter and GPS readings, we had medical diagnostics on the crew members. If you actually study all the numbers and readings, they all make sense – it constitutes a believable technology.”

Laser Beams
Paul described the components. “To create the light beams we watched the way laser beams flicker and jump, and mimicked a grip’s torch moving around randomly on set. The probes have a main scanning beam spinning around the axis, plus various other beams all seeking topological data. Our artist Romain Buignet built a fluid gas system for the smoke they emit, combined with matte elements that race through it to create the look of laser beams illuminating the smoke, and a pass for the surface. Finally all of this was composited together with the glowing red CG ball of the device.”

The holographics in character Meredith Vickers’ chambers was one of the simpler tasks Fuel undertook, but also one of the most attractive. The Art Department and concept team supplied a beautiful matte painting to replace one of the walls in the room and Fuel, led by Xavier Bourque, built a snow system for it, all done in Nuke. They added small snow flurries scattering through the light, and dimensionalised the cards made for the trees, mountainscape and snow.

“We treated it as a window through to another world. The lighting had to be bent slightly to shine on actors and elements and reflections added but not interfering with the DP Dariusz Wolski’s lighting,” Paul said. 

Words: Adriene Hurst
Images: courtesy of Fuel VFX and 20th Century Fox Australia