Director Yeon Sang-ho brought back much of his crew from velocity-infused 2016 Korean zombie blockbuster “Train to Busan” to deliver the goods for “Train to Busan Presents: Peninsula,” bowing in theaters Aug. 21.

While “Train to Busan” (the first widely released film of the trilogy, though made after the animated original film, “Seoul Station”) focused on a small group of survivors trapped on a bullet train during the start of a zombie outbreak, the current film takes place over the entire South Korean Peninsula, requiring greater imagination, more special effects and a wider collaboration among the crew.

Designers had to consider how the landscape would appear after the zombies established a foothold across the nation. Key scenes included a “Thunderdome”-style battle arena that pits humans against the undead and a car-chase sequence that covers almost the entire third act, in which the film’s quartet of heroes aims to get to the Port of Incheon with $20 million in U.S. currency that has been abandoned in a truck somewhere in the city.

Creating the Dystopian World

“To show what an abandoned Korea would look like four years later, the production team [led by production designer Lee Mok-won] re-created the actual locations to produce an old and worn-out look,” Yeon explains. Of course, fashioning a new world was not without difficulties. “My vision of the abandoned land was overgrown grass everywhere,” the director notes, “but when we tried planting the grass on set, it would die the next day, so the production team planted new grass on the set every time we scheduled a shoot.”

Scenes that included actual locations were augmented with special effects to create the nightmarish tableaux. “Filming ‘Train to Busan,’ I worked with cinematographer Lee Hyung-deok to figure out how to efficiently shoot scenes in a narrow train,” says Yeon, “while for ‘Peninsula,’ we worked mostly in front of a green screen. We discussed how best to film scenes for a background that had not yet been created. The CGI team was always present at the filming site so that whenever [Lee] would take a test shot, we could discuss graphics to use.

“VFX supervisor Jung Hwang-su, whom I worked with during preproduction as well as during shooting, was also the VFX supervisor I worked with for ‘Psychokinesis’ and ‘Train to Busan.’ For ‘Peninsula,’ on the CGI scenes like the car chase and the creation of the ruined city, we collaborated on various parts of the production, such as filming, art, stunts, etc.”

The Battle Arena

“I asked stunt director Heo Myeong-haeng to make the scene into a single cut, so the audience would be able to feel the urgency of the characters,” Yeon says of the life-and-death scenario, in which members of the evil Army 631 Unit bet on the outcomes.

“I asked choreographer Jeon Young for a new type of zombie to be shown. The result was burnt zombies who were stuck together and running on four legs. Jeon actually played the part of the four-legged zombie.”

Escape From Korea: Zombie Road

The chase sequence in the third act features actors in tight spaces, lots of high-speed special effects and vast areas for swarms of zombies to pour in. Yeon says his background in animation served him well in designing the epic finale.

“Most of the car-chase scenes in the second half of the film were made using CGI animation,” he says. “Most of the animation was created in preproduction. To create the [two-car] chase scene with the Army 631 Unit, we used CGI to scan actual stores, like a tool shop in the Guro-Gu District, and synthesized the city using CGI. We then studied the space and discussed how to design the scene in the narrow alley using the background we created.”

Yang Jin-mo, the Oscar-nominated editor of “Parasite,” with whom Jeon had worked on “Train to Busan,” helped Yeon cut the animated footage in preproduction. “Even before we started filming, we had finalized the editing for the animation and discussed the angles we wanted to achieve,” Yeon says. “We [then] only had to film the scenes where the actors were driving.

“For the second half, we combined the driving scenes with the already edited CGI animation and smoothed out the scene.”