An excerpt from issue #54 of befores & afters magazine on ‘War Machine’.
Seeking to outrun the machine, the Rangers commandeer an armored security vehicle (ASV), nicknamed the Guardian. A number of practical vehicles were crafted for use on location, and for filming on a motion base on set, in order to film the thrilling chase between the machine and Guardian that also includes a lengthy oner. Eventually, the Guardian is destroyed and most of the remaining Rangers are killed.
“The Guardian is a Mercedes Unimog,” advises visual effects supervisor Raymond McIntyre Jr. “We purchased three of them, took the body off, put on a wooden body with a tack-welded frame to hold it in place. Then, of course, we had a digital version built by Framestore.”
“We had to match a few different ‘builds’ of the Guardian for different scenes where they were building on the outside of another vehicle, or mounting it on a different vehicle altogether so they could drive around with the same agility they needed,” discusses Framestore visual effects supervisor Joao Sita. “Then when they did the interior shots for the Guardian chase, that’s a new build, 20% larger, so they could fit the camera crew inside it. That became challenging as we went down the process, because we go from inside to outside the vehicle and we had to compensate for the scale discrepancy.”
Part of the chase sees the machine launch a ‘carpet bombing’ attack on the Guardian via many of its orbs, with the explosions cascading towards the fleeing Ranger vehicle. Framestore referenced actual mine charges for reference of the timing of the carpet bombing explosions, including for how those charges weakened the surrounding terrain before the main flashes. Part of that sequence was shot with the practical Guardian—including with a pole gag installed to allow it to kick up—and part of it was made up of a completely CG vehicle, machine, orbs and explosions. “One of the shots would start, say, with the real Guardian,” outlines McIntyre Jr., “but we needed it being even more kicked up as the bombs hit. So we switch from real to CG and then added all the explosions and nearby trees so that we could add interactive light on them and feature debris and everything.”
The carpet bombing causes the Guardian to careen off the road and down a tree-covered slope. “That was actually a cleared path,” reveals McIntyre Jr. “We used the practical Guardian to shoot it, but that was all digital trees, digital interaction, digital smoke, digital dust—all done by Framestore and it’s beautiful. I mean, it’s a shot that nobody will ever look at and say anything about, I think. They won’t realize how much visual effects work was involved.”
The machine catches up with the Guardian at a ravine. Here, the machine uses its jets to jump down from a cliff above. What follows is an intense chase as the Rangers attempt to fight back with live ammunition. A rock fall subdues the machine, briefly, but the Guardian is ultimately destroyed. Much of the environment for the chase was digital, alongside a CG machine and CG Guardian. McIntyre Jr. scanned a kilometer-long section of a rock wall in New Zealand with his drone for the Guardian chase section, which Framestore then used to help build up the area.
For the interior of the Guardian, production filmed on a gimbal against bluescreen, rigged by the special effects team. “We set up the gimbal and mounted the interior set onto the gimbal so they could have real rock and roll movement,” describes special effects supervisor Peter Stubbs. “We had also been involved in little gags for the Guardian, like the black dust and air coming out of its exhaust. The machine guns, too, were a mixture of props and armory and us, to get them to operate.”
Framestore’s CG Guardian was carefully animated to match what the real Guardian could do. The team relied on plates shot of the practical vehicle for tracking, matchmoving and to get a sense of the general movement. “There was a lot of interest,” says Sita, “in how fast the Guardian could actually go, especially to make sure we were showing the machine couldn’t keep up with it at times. Daniel and his animation team came in and worked out all the mechanics, the suspension, how much the body shifts when it goes through the terrain, and how much the terrain could be flat or undulated.”
“It was an interesting challenge,” mentions Framestore animation supervisor Fotheringham. “Because, depending on the photography, the vehicle driving along can actually feel slow. So sometimes we’d add some bushes or rocks in front to make things feel faster. We were always looking to get some weight and peril in the movement of the Guardian—you can only do so much with it just moving left and right and going up and down. So, say if there was an explosion, we’d try to make sure the movement didn’t feel contrived, that it felt like there was a deliberate action. What we found, too, was when they cut into the characters inside the Guardian, it really showed how bouncy it was. The inside of the Guardian was pretty chaotic, which was cool. It really added to it.”
“We built in a lot of the oscillations into libraries that we could bring in,” adds Fotheringham. “It wasn’t dynamics, it was all keyframes. We had to really find ways to solve the movement. Even just little things like when the vehicle turns left, all the weight goes to the right, or continues straight, actually, but the car will dip down to the right. We’d always look to the photography to make sure what we were doing felt right.”
The oner itself was imagined in previs and postvis by Aurora AI, alongside some more old-school methods with cardboard boxes and a 3D print of the Guardian. The stunt team also made a stuntvis to help orchestrate the action. Several passes made up the final oner, all stitched together during whip pans by Framestore. The oner takes place largely from inside the Guardian, but more and more of the outside world becomes visible as pieces of the vehicle’s body are ripped off from laser and shrapnel hits.
The reveal of the damage to the Guardian from inside became known as the ‘Swiss cheese effect’,” jokes McIntyre Jr. “The machine was behind the Guardian all of the time, and it obviously had to be shooting at the Guardian almost all of the time. Therefore, the Guardian needed to take hits and holes. All of the hits and holes in the back of the Guardian throughout the sequence were digital. When you see a hole, that’s a digital hole. All of the dust, debris, sparks—anything moving inside of this environment—is digital all of the time. There were also hits happening off-screen but then we’d add interactive light and sparks.”
To deal with the digital vehicle holes, to show what was happening through the holes, and to add the elements inside the Guardian, Framestore embarked on a meticulous tracking effort for the oner. This also involved body tracking the Rangers, particularly for a moment one of them loses his arm. “Once that tracking was all done, layout and animation took over the camera,” explains Sita. “What we found was that sometimes the vehicle was actually static and the movement was coming from the camera, as opposed to the other way. We just had to adapt our motion blur to suit.
Artists at Framestore referenced military vehicles that had been destroyed during wartime for how their shells are impacted. “We looked at, how does the projectile go through a metal surface?” states Sita. “We matched that, and then created all the shrapnel and smoke and the molten metal. It was a lot of fun. We couldn’t stop adding stuff to the shots.”
A second section of the chase reveals more and more of the Guardian’s body having been blasted away, and 81 struggling to keep hold of a fellow injured Ranger, 7 (Stephan James), who is on a stretcher. At one stage, with the point of view now outside the Guardian, the camera swoops back inside to continue following along the action, until 81 fires on the rocky cliff wall and causes a rockslide—”Framestore did such a great job on the animation here,” states McIntyre. Jr,” coming up with a way for us to get back into the Guardian.”
“For this shot,” outlines Sita, “we had done a couple of tests for a different purpose with the camera outside seeing the crash. I think everybody saw that there was a lot of scope that could be played if the camera would go outside and show the environment and the Guardian in the environment. Then postvis did a couple of tests for some wrap-around cameras. We ended up taking those and finding a way before the conical laser cuts through the roof of the Guardian to move back inside. Daniel came up with this idea where the vehicle actually would be avoiding one of the conical lasers and we ended up sideways to the camera that then would allow the camera just to continue its motion inside. It made it feel linear to the scene—even though it’s not part of the oner—but it matched the camera flow for the sequence.”
Throughout the sequence, Framestore simulated countless explosions inside and outside the Guardian, instigated by laser blasts and also by the Guardian hitting rocks, trees and other terrain. Sita mentions that the approach to the explosions here involved animation driving every impact timing. “We didn’t want to go from blocking animation to FX and get something where the timing was off or the perception of the size of the explosion not translating the same way. In animation, we therefore had a couple of basic geometries for representation, very rudimentary, but when you played the cut with the playblasts you would still get a sense of the impact timings, how long they would last, how much of the screen space was going to be occupied later with FX, which I thought was key to get this stuff working.”
“Yes,” agrees Fotheringham, “in the past, you might just throw in a primitive sphere or something like that to show the timing of an explosion. Then FX go and do this absolutely incredible explosion, but it might have multiple beats to it, which might not be quite right for the buildup of a sequence. So, we did it a little different here to make sure everything was much more calculated this time.”
