One of the new characters introduced into the Marvel Cinematic Universe in Taika Waititi's Thor: Ragnarok is Valkyrie, the Asgardian warrior played by Tessa Thompson. She's important for a lot of social reasons, and is also a major part of the most incredible visual effects scenes in the movie.
In a stunning slow-motion flashback, we see Valkyrie and her fellow warriors take on the evil Hela (Cate Blanchett) while riding majestic flying horses. To achieve the distinctive and intentionally disorienting slow-motion scene — which shows the arrival of the horses, Hela's retaliation with deadly blades, and the slaying of many warriors — the filmmakers collaborated with Satellite Lab, the inventors of a new capture technology that combines moving light with high-speed imaging. Visual effects studio Rising Sun Pictures then took this footage and added substantial VFX for the final scenes.
Making light move, fast
Thor: Ragnarok visual effects supervisor Jake Morrison describes the technology that enabled the slow-motion photography as "like a new age version of bullet time," referring to the multi-camera array used to film the famous scenes in The Matrix. "But," notes Morrison, "whereas bullet time enables you to freeze a moment in time and then move the camera around at impossible speeds, depicting it all realistically, this is literally like a 180 degree version of that."
The patented technology, from Satellite Lab, is called DynamicLight. Co-founder and visual artist Carlo Van de Roer told SYFY WIRE he was looking to "create a toolset to control and play with the representation of time and space within in-camera filmmaking. I wanted to move light sources so fast that the rest of the world would appear standing still, giving us the ability to move light sources within a world suspended in time."
Van de Roer founded Satellite Lab with Stuart Rutherford (co-star of Waititi and Jemaine Clement's What We Do in the Shadows) and Matias Corea (the co-founder of online portfolio site Behance). What they developed was a way to move a light source at over 10,000 feet per second -- that's eight times the speed of sound.
"The speed and acceleration of the light sources are controlled with software so that the motion in the scene and the motion of the light sources can be adjusted as independent variables," explains Van de Roer.
Filming the scene
For Thor: Ragnarok, Satellite Lab's rig was a 20-odd-meter-wide ring of steel truss suspended above the actors. Connected to the truss were more than 145 hot shoe flashes.
"The software that they've written effectively synchronizes each flash to a single frame of action with a high-speed Phantom camera," explains Morrison. "We shot with a Phantom Flex4K at about 1000 frames a second, and what happens is you get this moment where time slows down to an incredible soup. You get into really thick, slo-mo action, but then, almost impossibly, the light actually does a full 360 degree loop around the actors in that moment."
On set, all this happens in an instant ("It's almost like a fashion shoot when the flashes go off," says Morrison). But when the footage is played back, that moment is elongated and you essentially get one frame per flash, translating to about five seconds for each flash burst.
Thompson and Blanchett performed their scenes knowing that a crucial moment had to be captured in just these super-brief instants, which Morrison says was a major challenge.
"You're basically trying to squeeze in these incredible acting beats and performance moments into literally less than half a second. Then when you play it back, it stretches that moment out, and because the way the light plays around, it really models the face and you can really see everything that's going on in there. I think there's some beautiful imagery we created in there."
Real and CGI horses
The moments were all filmed against bluescreen, and even included capturing a real horse standing in for the many that would finally grace the screen. The Third Floor helped previsualize or "previs" the flashback scenes so that they could be accurately shot. Since only one horse was filmed, previs was able to show how to shoot multiple angles of the same horse so that it could be duplicated. Many of the horses and riders were also fully computer generated, thanks to the efforts of Rising Sun Pictures.
Morrison says in a scene that was always going to include a lot of CGI, it was important to have as much real photography in there as was possible. "There are CG horses in the scene, but if everything is CG in the scene, I think you lose some of the DNA of being 'real.' It was really exciting to be able to push that a little bit further, shoot with real riders, real horses -- we put the wings on later and did CG backdrops. There's distant Valkyrie falling in the background and even horses that the art department built as beautifully detailed three-foot-tall horse maquettes that we were dropping on wires and shooting with the rig."
Shooting one particular scene from the flashback had Morrison in hysterics. It's the shot of the Valkyrie falling on her back in slow motion with a billowing cape.
"That genuinely involved me shooting a run of about 20 or so different moments where the Valkyrie stunt performers are on a trampoline. They jump up, do a big bounce, go bounce, another bounce, go for a big leap, then go into a dead duck falling mode, at which point Carlo Van de Roer would be on the button and capture that moment. There's no CG capes on that one or anything like that. That's the actual footage, but it was so successful that we ended up using it in the marketing and then in the film of course as well."