7 LAWS OF SCIENTIFICALLY ACCURATE VGX
THE TEAM BEHIND AMAZON’S CRITICALLY ACCLAIMED THE EXPANSE SERIES SHARE THEIR SECRETS TO PUTTING THE SCIENCE BACK INTO SCI-FI
Is learning physics the key to great visual effects? VFX producer Krista Allain and VFX supervisors Bret Culp and Chris Nokes certainly seem to think so. With good reason.
For six years now, they’ve formed part of the team behind The Expanse: a sci-fi show so wellknown for its scientific accuracy that it was even featured on the front cover of Physics Today by season two.
For the multi-vendor visual effects team, who are now working on season six, it’s meant delivering an average of more than 2,000 shots per year – the same numbers as Avengers: Endgame. And this is all while ensuring that each and every frame is as scientifically accurate as possible.
It’s a lot of hard work, but the added authenticity has been worth it. Despite a tight television schedule, the show’s impressively high production values have attracted a serious following, even in the scientific community. In fact, when Syfy cancelled The Expanse after three seasons, it was the show’s devoted fanbase, including real-life astronauts like Andreas Mogensen, that campaigned for Amazon to pick the series back up.
By then, The Expanse’s adherence to science stood out so much that Jeff Bezos announced the acquisition at an International Space Development Conference.
So, how do you go about creating effects so realistic they could save your show? To find out, 3D World caught up with Allain, Culp and Nokes to learn their top secrets to creating scientifically accurate VFX.
1. USE REAL-WORLD REFERENCES AND HYPERDETAILED SCRIPTS
For the team behind The Expanse, real-world reference is the first crucial step towards delivering realistic results, especially when it comes to the show’s hundreds of fully digital shots.
“We believe that science fiction is a reflection of the contemporary times. The Expanse is a story about the colonisation of our solar system, set in the not-too-distant future. That means we can’t rely on completely fictional technologies like warp drive when developing our visuals,” begins Culp, who works with Allain at The Expanse’s production company Alcon Entertainment. “The show needs to be futuristic, yet recognisable to scientists today.
“We also always update our effects to reflect new advances
“WE ALWAYS UPDATE OUR EFFECTS TO REFLECT ADVANCES IN SCIENCE. IT’S A CONTINUOUSLY EVOLVING PROCESS” Bret Culp, VFX supervisor
in science. When NASA released new footage of what the Martian landscape looks like, we updated The Expanse accordingly. It’s a continuously evolving process.”
Luckily, the team have some serious help. The series is led by Naren Shankar – a showrunner with a PHD in engineering physics and electrical engineering from Cornell. Pre-production typically starts reviewing his detailed notes in the script based on science as well as original The Expanse books: a series of novels written by Daniel Abraham and Ty Franck.
These detailed scripts go on to inform the concept stage, where Allain, Culp and Shankar use daily cinesync sessions to remotely communicate with a dedicated concept team at North Front Studio. Together, they work to create art that adheres to both the science and the books. That’s when an in-house post team as well as up to eight vendors on the show, including Rocket Science VFX, Spin VFX, Mavericks VFX, MARZ, Torpedo Pictures and Krow VFX, will get involved.
“Our role is to develop the concept art further by integrating how that object would move in real life,” says Nokes, who works for Rocket Science. “The Mech bots from last season are a good example. The concepts were amazing, and Naren and Ty were very specific about the types of joints they wanted Mechs to have. When we went in to build them, however, we needed to realistically showcase the limitations those joints would have and how that would affect the way a Mech would walk. We produced an animated walk cycle with those joints, and it wasn’t how everyone pictured it.
We all decided to rethink the joints for that reason.
“Remember, even a simple element like the joint type or where the knee is can make a big difference on how a character walks. On The Expanse, everything needs to behave realistically, even when it comes to the joints on a completely fictional character.”
2. NEVER FORGET GRAVITY
There’s no way you’ll ever come across a spaceship with internals designed to look like a living room on The Expanse. The reason is simple: it doesn’t adhere to the rules of gravity. Instead, spaceships are built like the Apollo. They have stacked floors in a rocket-like shape that ensures gravity is generated by being under accelerating thrust. If you lose thrust, gravity cuts out. Planets, too, are always depicted with a realistic gravity on the show: to prepare for what they consider to be an inevitable battle between Mars and Earth, Martian soldiers carry out combat training under Earth gravity conditions. Characters from outside Earth can even be tortured simply by being placed under Earth gravity.
“Gravity is a whole village effort of work,” begins Nokes. “We use a site, www.artificial-gravity.
“WE HAVE A MANTRA ON THE SHOW – THERE’S NO UP OR DOWN IN SPACE” Krista Allain, VFX producer
com/sw/spincalc, where you can actually calculate gravity. So, when we are creating a shot with the Medina space station, for example, the first thing we do is calculate the rate at which it would need to spin to generate 1/3 gravity as per the original books. We then integrate those figures directly into Maya, so Medina always rotates at the right rate.”
“There are several pieces of advice we’d give to anyone who wants to quickly depict a realistic version of gravity,” says Culp. “First, try long shots. One of our key opening sequences involved a long shot of the camera moving inside the hero ship, called the Rocinante or Roci, then going along a docking bridge following two of our heroes. On set, we wired them so they were upside down and rotating, walking down the hall. It was a fantastic shot, and immediately set the scene by showing viewers there was no gravity within this environment.”
“Another technique is to use your props to highlight realistic gravity,” Culp continues. “We take advantage of the Coriolis effect to manipulate fluids throughout The Expanse. All a character needs to do is pour a drink, and dependent on the gravity on their ship or planet, you’ll notice the speed and angle of the fluid will be different.”
3. THERE’S NO UP IN SPACE
From the very beginning, one of The Expanse team’s primary objectives was to represent space in a way that astronauts would recognise. One part of doing this was creating realistic gravity, and another was depicting a distinct lack of direction.
“We have a mantra on the show – there’s no up or down in space,” explains Allain. “Our viewers keep us on our toes with this. For season two, we had a shot where we were showing Jupiter with its bands
going vertical, and the sun’s light coming through from the side. One of our dedicated fans pointed out that the bands always run parallel to the sun. It was a learning experience and further reinforced how we needed to compose our shots differently to ensure they were right.”
“You need to forget about what you’ve seen from other shows, or in compositions and concept shots of space,” agrees Culp. “If you want to show several planets across a frame but they won’t fit, for instance, there’s no reason you can’t go vertical and really use the space. In space, objects on the top aren’t always on the top, and the bottom isn’t always the bottom. We always work hard to present space and the planets in a way that’s different to how people typically perceive them.”
4. CREATE EXTENSIVE PREVIS FOR ACCURATE LIGHTING
The team also produce extensive pre-vis in Maya to view how concepts can accurately go from script to video form. This is especially useful when it comes to visualising accurate lighting on the show’s space shots: considering there’s no up in space, the lighting is always tricky.
“We don’t treat pre-vis as work that we’re going to throw away, or as simply a way to preview character animation. We treat it as the first version towards a completed render,” reveals Nokes. As well as helping the team visualise what parts of an asset are in frame so that they can develop more detail in those areas later on, pre-vis also helps when planning the on-set practical LED and smart ray lighting – which can even involve up to 3,000 separate lights for some sequences.
“Last year, we were working on a sequence involving a character jumping out of a ship and spinning around in space. One of our DPS, Jeremy Benning, used our previs to build a giant spinning light
“WE WORK HARD TO PRESENT SPACE AND PLANETS IN A WAY THAT’S DIFFERENT TO HOW PEOPLE TYPICALLY PERCEIVE THEM” Bret Culp, VFX supervisor
rig with three-axis rotation. This meant that when the actor was on set, Jeremy could shoot exactly how the light in the background would affect the actor’s face, to match the planned comp,” Nokes continues.
In the last few years, the team incorporated Redshift GPU rendering into their workflow to make pre-vis even more realistic. “We render with motion blur, show lighting, and higher-quality FX,” Nokes adds. “That’s especially useful for pre-vis explosions, as we can make them more typical of the final look.”
5. GIVE ARTISTS A PHYSICS LESSON
“There are many other challenges you may not think of in space. How do you show a ship that’s moving fast? Space is infinite, and the stars are so far away that if you’re depicting it realistically, you’re not going to have a parallax effect or have fictional technologies like warp drive to see stars come past if you’re moving quickly,” explains Culp.
What the post-production team do instead is what they affectionately call basic training. “First, you get an animator who is new to the show and say, here’s a 56-metre ship. You now have to make that look fast and guess what – the stars don’t move,” says Nokes. “On top of that, you also have to ensure the ship looks like it’s rotating in a zero-g way whenever it turns. So, the first thing an animator has is a physics lesson.”
In order to give a sense of movement in space while maintaining scientific accuracy, The Expanse team make clever use of camera work. “We look at car chases as inspiration for our flight sequences,” Culp tells us. “Ships move across full frames. While you can’t make stars move with warp drive, you can make them move through camera movement. You can pan and tilt the camera, and still get that same sense of speed.”
6. PAY ATTENTION TO MEASUREMENTS
According to Allain, Culp and Nokes, one of the biggest challenges for the effects team on The Expanse is right there in the title. “Getting a scientifically accurate scale is one of those things we all always have to try to remember to do,” says Allain. “The idea of a Ring gate is a great example. Each ring is a torus shape with twisting edges that spiral around its body. Ships
travelling through a Ring go through a wormhole so it’s a fantastic visual for the story. The problem is, one gate is 1,000 kilometres in diameter.”
“That means it’s impossible to capture the entire thing in a single frame while also seeing a ship go from one end to the other, as the ship would be a pinprick. You constantly have to visualise these massive scales and come up with clever workarounds – like seeing the gate from multiple characters’ points of view to make the shot more visually engaging.”
This is where 3D concepts, which are built using Maya and Substance Painter, help. “North Front Studio will build the framework in 3D. We then validate the scale, down to the exact centimetre,” says Nokes. “If you want your show to be realistic, remember to measure all your assets, especially when you’re creating anything that is at a human scale, like doors or bridges. Even seemingly insignificant details, like how tall or wide the door of a ship is, can make a big difference when there’s a script in a later episode that has someone coming out of that door and hit their head.”
7. LIVE AND BREATHE SCIENCE
“Lastly, the reason we’re so successful at creating scientifically accurate effects on The Expanse is because everyone lives and breathes science,” reveals Nokes. “I read the books and learned everything I could about the show before working on it. And it’s not just me. You have to get to the point where you fully understand the world inside out. Guys like Ty and Daniel wrote the book, they’ve done an immense amount of research. And Naren is a scientist. If you can’t keep up with them, you won’t be able to make the right creative decisions.”
“We always make sure to keep up with science and the scientific community,” concludes
Culp. “Some of the cast and crew even screened a scene where the Roci touches down on the surface of the alien planet, Ilus, to the team at NASA’S Jet Propulsion Lab and aerospace company, Blue Origin. It took us so long to ensure we got that touchdown sequence just right, using real references.
“Then the Blue Origin team applauded when the Roci touched down during the screening. We even recently spoke to a scientist who told us Blue Origin has a Rocinante board room! When you hear stories like that, you know you’re doing something right.”
“WE CAN CREATE SCIENTIFICALLY ACCURATE EFFECTS BECAUSE WE LIVE AND BREATHE SCIENCE” Chris Nokes, VFX supervisor