You wouldn’t think that the vicious Game of Thrones dragons and the cuddly (and critically acclaimed) titular bear from Paddington 2 would come from the same creators, but Kev Cahill has been on both of those VFX teams.

“I’ve got a strange range of films,” the filmmaker confesses.

While his work definitely spans the genre spectrum, all of it together makes for quite the impressive sizzle reel: Alice Through the Looking Glass, Fantastic Beasts and Where to Find Them and Star Wars: The Last Jedi—decidedly “VFX-heavy” movies. Most recently, Cahill served as VFX supervisor on The Green Knight, and the Arthurian-inspired fantasy film feels like it fits right in on his resume.

For those of us uncertain what exactly a role like that entails, Cahill breaks it down: “A VFX supervisor makes things that aren’t achievable in-camera achievable on the computer, all with the director’s vision in mind. So for The Green Knight, we’ve got giants and talking foxes and things like that that don’t exist. We help make those things a reality.”

Dev Patel in 'The Green Knight.'

Those kinds of flashy and fantastical creations tend to dominate movie trailers and elicit many oohs and ahhs, but Cahill emphasizes that VFX work is often a lot more subtle. He says he spends just as much time on practical problem-solving as he does finessing dragon scales or detailing bear fur. In fact, a good portion of his work in movies might actually be what you don’t see.

“I love the visual effects side of things because we get the magic of films,” gushes Cahill. While some of that is certainly creature creation, “some of it is also making different types of camera moves that can conceptually tell the story better, or wouldn’t be achievable unless we connected two shots and created something that you might not even realize is VFX.”

“On The Green Knight, for instance, we shot the exterior of a castle in Tipperary, Ireland. But when you come out of the castle gate, it’s a fully functioning, modern-day town. We’ve got to try to hide those things,” Cahill explains. To solve that problem, the team shot additional elements elsewhere in Ireland, then seamlessly combined those pieces in postproduction so audiences can “get a [more complete] sense of the medieval world.”

This trickery requires a good grip on practical filmmaking skills and cutting-edge computer graphics (CG), and Cahill has been attuned to that dual demand for a while. He recalls being enthralled by Jurassic Park when it came out nearly 30 years ago, and now realizes that “the beauty of [that classic] is that it has what all the best VFX films have: a balance of reality and CG.”

“Now that we can do so much on the computer, sometimes people lean into that a bit more,” he shares. “And what you kind of miss sometimes is getting that real interaction with things. If you can get the first few steps of something practical and then add your VFX bits towards the end, you figure out lots of things that you might not have if you decided to do it all CG.”

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“All of the best VFX films have a balance of reality and CG—and that always gives you the best results.”

The work of VFX teams is often at play in projects you probably assumed didn’t use any at all, like dramas, comedies or all kinds of indie films with smaller budgets. When Cahill worked on the indie miniseries We Are Who We Are, from Oscar nominee Luca Guadagnino, the director told him he wanted it to feel like there weren’t any visual effects at all.

Even though it might sound like a walk in the park, Cahill had his work cut out for him. “You’re trying to maintain a reality in a setting that’s very far removed from a big sci-fi or fantasy film. A lot of the effects are helping to stay within the reality of the story that [Luca] was telling. Set extensions have to be gritty and real—like they’re nonexistent. They can’t draw attention to themselves at all. I really enjoyed that side of things. It’s where VFX can really help indie filmmaking.”

Another example of Cahill's work, from 'Paddington 2.'

No matter the budget, the genre or whether they’re matching reality or creating fantasy, VFX teams can’t exist in a silo. Collaboration with other filmmaking teams is essential, and Cahill’s collaborators on The Green Knight are some of the best in the business—tried-and-true A24 aesthetic experts like director of photography (DP) Andrew Palermo and production designer Jade Healy.

“Every day you’re checking in with DPs, to see if we need to frame things that weren’t in the shot initially,” Cahill reveals. “[If so,] how big is the vista we want to see when the camera goes through the gates of the castle? And usually, certain parts of a set are built, but then [the VFX team] is going to be building out the rest. What’s the architectural structure of the building [to be created or extended]? And how would it fit into the landscape that we’re shooting on?”

A writer and director himself, Cahill feels especially prepped to take feedback and run. “Having gone through some of the joyful pain of making a film, having done a few of those projects myself helps me understand what the directors are looking for. Then I boil it down to what [exists] within the visual effects world to help that, to help the story go forward.”

The Green Knight represents a great fusion of his backgrounds in indie filmmaking, the fantasy genre and that balance of reality and CG.

“A lot of medieval and fantasy films can have more of a swashbuckling tone sometimes … So there was something quite nice and controlled with The Green Knight. There was a reality to the strife of the characters that you don’t always get in a fantasy film. Dev Patel’s performance in it and what we got on set was really strong and powerful. No shots captured were throwaway shots—everything was measured and considered, as director David Lowery is in every step he takes and every word that he utters.”

The Green Knight, which Cahill considers a highlight of his career, releases in U.S. theaters on July 30.