Issue link: https://digital.copcomm.com/i/1495163
14 cgw j a n u a r y • f e b r u a r y • m a r c h 2 0 2 3 "We had a special trench made for a tank to run over with cameras underneath," he recalls. This allowed the team to capture visual details from below without needing to re-create them in animation. "There's so much going on when you're close up under a tank. There's the weight of the chains, the clunking, and there's stuff rattling." "I always called it the 'step backward' approach, where nowadays you do a lot of CG animation and then blend it with photographic stuff, little elements, little dust puffs — everything," Petzold explains. "We did it the other way around, as we tried to use as many photo- graphic elements and then help with CG blending — like particle sim- ulations and dust — that we ran in Houdini. It was really rewarding, and right away, everything fit on the screen." Rooted in Reality The film's large-scale battle sequences required an extensive blend of practical and visual effects elements. Even with the spacious practical location, the tree line and houses were visible in the distance. "Edward wanted it to be an endless battlefield. At the same time, it had to feel claustrophobic for the soldiers and for our actors," Petzold recalls. "We smoked up the whole thing as much as we could on set. Then we also layered in CG smoke and different speeds of fog." He also worked closely with the makeup department to enhance battle wounds and carnage. Petzold collaborated with the film's special effects team to cap- ture real explosions that would be integrated into the VFX pipeline. "All of the explosions that we put in with visual effects — they were all real. There are no simulated explosions," he reveals. "That was the great thing about having this gigantic set. I could go off to the side, still be on set technically, and blow up stuff." He and special effects supervisor Kamil Jaffar experimented with different materials to achieve a wide range of different explosive effects. "That was a lot of fun on set, but it required a lot of planning," he adds. Running into Infinity The battle sequences required a massive amount of rotoscoping work. "We had long takes of 200 soldiers running, or even more — 300 at some point — and you don't just want to put the smoke or the fog behind everything. You want to have stuff in between them," Petzold explains. "And if a soldier is running, every person is always completely motion blurred." The tree line in the background would also need to be removed to achieve the illusion of running into in- finity. "We wrote some scripts to help us with the keying versus ro- toscoping, integrating all that stuff quicker," he adds. "But there are some shots in there that took three months alone in rotoscoping just to be able to start." Flamethrowers, used for the first time in WWI, posed an addition- al challenge for the VFX department. "As horrible as they are in the matte painting, they're like beautiful little details that go off. You have a bird's-eye view shot of the battlefield, and not only do you see the soldiers running, but you also see little things blowing up," he recalls. "It was a sort of beautiful image for a horrific scene." Battling the Elements Petzold carefully selected the VFX vendors that helped deliver key el- ements of the film. "I chose UPP in Prague as the major studio for all the heavy liing because I worked with [VFX supervisor] Viktor Muller on The Terror," he explains. "It wasn't the same work, but it was sort of the same technology." Cine Chromatix in Berlin also assisted with a few shots that required weather, environments, and set extensions. A scene in which the two lead actors risk their lives to steal eggs led to an unexpected challenge for the VFX team. "It started snowing in the morning when we got to set and we thought it looked beau- tiful," Petzold recalls. The snow gave the sequence a powerful sense of serenity, but unfortunately, the winter wonderland did not last. By noon the sun was out, the snow had stopped falling, and it looked like summertime again. "We had to improvise and think about how we were going to con- tinue. We didn't want to reshoot those first shots because they were so gorgeous, so we decided to do a CG winter for the rest of the se- quence," he explains. This led to more collaboration with the special effects team. "SFX gave us a nice carpet of fake paper snow so that we at least have the interaction of the guys run- ning and kicking up snow and dirt," he continues. The VFX de- partment added a full CG back- ground and scenic weather ele- ments to complete the illusion. Mapping Historical Details Extensive 3D scanning and modeling enhanced the film's historical accuracy. This includ- ed scanning the actual train car in which the armistice agree- ment was signed during WWI. "We went to a museum and scanned the train to replicate Every explosion was captured practically and integrated into the VFX pipeline.