How the ‘Ad Astra’ VFX Team Turned Rover Battle Into a ‘Fury Road’ Chase on the Moon
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James Gray (“Lost City of Z”) isn’t accustomed to directing action scenes, but he made sure that his thrilling “Ad Astra” Rover battle on the moon, with astronaut Brad Pitt being pursued and attacked by pirates, was unconventional. “In some weird way, it was shot on location,” Gray said.
The location was Death Valley. Cinematographer Hoyte van Hoytema ingeniously came up with a special 3D rig with Alexa 35 infrared and 35mm film cameras to shoot the sequence in the desert with stunt doubles in motorized Rovers (overseen by second unit director Dan Bradley). This “virtually created unfiltered hard sunlight firing through the atmosphere-less air,” said van Hoytema, who also slowed down the motion of the image to add low gravity credibility. “Tension wouldn’t necessarily come just from speed, but more from the fucked up physics and the story itself,” he added.
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Method Studios then replaced most of the desert surface with animated lunar surface, along with the strange, explosive action, and then composited closeups of Pitt shot by van Hoytema in an LA studio. “It was an [interesting] combination of approaches,” said production VFX supervisor Allen Maris. “Because of the clear, blue skies, those turned black in the infrared, and you got a high contrast look on the ground so that the sand-colored terrain would turn almost grayish white. It was a very good look — a base layer. Everything was replaced mid-ground all the way into the deep background. That’s obviously because there are no sand dunes or rolling hills on the moon. But we retained as much of the skies as possible except when they were cloudy.
“And then, as you got close to camera, [Method] tried to do simulations of the moon in a vacuum to create the kinds of dust plumes and trails that Rovers leave behind as they drove. And then in all of the wide shots, we replaced everything so we that we could get those craters, the pot marks, and the texture that the moon has.”
Fortunately, there was plenty of high-res NASA moon photos to analyze along with the “For All Mankind” documentary. Method discovered some very helpful visual clues. “All the little craters and other things that make up the texture of the terrain are very different and very strange compared to the Earth,” said Jed Smith, Method’s VFX supervisor. “The reason that we had to replace most of the background terrain from the desert footage is that when you start to look at those dunes, you see patterns of wind formed in the sand and the light. It also almost throws off your perception of distance because on Earth there is atmospheric perspective, which hazes out things that are further away, but it’s not like that on the moon.
“We overlaid new moon texture, keeping as much of the plates as we could,” Smith added. “The default procedure was to keep the Rover practically, add other CG Rovers, and do a blend on the CG moon that we created with foreground as plate and background as moon. The portion that was shot on a stage in LA over black for the closeups with Pitt was tricky with no chroma screens for us to extract. But they had one lighting source that would try to mimic the lighting on the moon, which actually worked quite well.”
Camera movement from the closeups on set were matchmoved, and reflection passes were done for the helmet visors. The other CG component was additional aerial shots of the moon to show off the action and to point out the position of the Rovers in relation to each other as the action progressed to the dark side of the moon.
“It was an opportunity to show off the procedural look dev system that we built for lighting and rendering the moon,” said Smith. “One of my favorite shots is where we see the power station with all the solar panels and the lights glinting off it and the pirate Rovers approaching. Every shot is a new position and a new background, and we needed to help with the continuity.”
The other creative look dev process involved the gunfire and explosions. The pirates shot at Pitt with special guns called Stilettos, which required a credible projectile. “We needed a justification for why we would see tracers,” Smith said. “This was a key dramatic moment. It had to be dangerous and scary. We invented the idea that the Stilettos were magnetically accelerated railguns shooting out molten chunks of metal. This was in a vacuum where there’s no atmosphere, but if it’s molten you could see something that’s bright with a lot of kinetic energy. We created the reddish tracers and extra explosion elements of moon being thrown into the air, both shot practically and done in CG.
“Then there’s artillery support that helps on the dark side of the moon by firing missiles,” added Smith. “These are standard rocket engine-propelled missiles with orange flame coming out of them. They are launched from the base, arcing over us and the stars in the background, ending in big explosions. These were full CG with effects simulation for the explosions. We found a test online of trying to simulate an asteroid impact in zero gravity on the moon in a vacuum and replicated that look. The debris was kicked up in a cone shape and it just kept going up.”
It was clearly like watching a war movie on the moon — “Apocalypse Now” in space.
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