Since its premire in December 2023, the Disney+ young adult fantasy series Percy Jackson and the Olympians has not only attracted a wide and enthusiastic viewership, but has been acclaimed by critics for, among other things, its faithfulness to the source material, its performances, and, notably for our immediate purposes, its worldbuilding. Based on Disney Hyperions best-selling book series by award-winning author Rick Riordan, and starring Walker Scobell, Leah Sava Jeffries, and Aryan Simhadri, the series tells the epic story of 12-year-old modern demigod Percy Jackson (Scobell), who is accused by the sky god Zeus (Lance Reddick) of stealing his master lightning bolt. With help from his friends Grover (Simhadri) and Annabeth (Jeffries), Percy must embark on an epic quest to find the lightning bolt and restore order to Olympus.To help with the visual component of the aforementioned worldbuilding, the creators were fortunate to have the services of a number of leading VFX studios, including London-based MPC and, critically, Industrial Light & Magic, whose groundbreaking StageCraft LED Volume technology which integrates real-time animated environments in live-action shoots played a central role in the production.As we get ready for a new season, which is based on the second book of the series, The Sea of Monsters, and is slated to be released in 2025, we spoke to Senior Visual Effects Supervisor Erik Henry about the highlights and challenges of the Season 1.Dan Sarto: Why don't you walk me through the different types of visual effects that we see across the season, and highlight the things that were most challenging, or that stand out for other reasons?Erik Henry: Well, Id have to start with the Minotaur, because for us that was a very challenging scene. It's hard to make something believable that runs on all fours, then stands up on its hind legs, and can mix it up. Thats the sort of thing where, if you dont get it right, people are going to be turning it off. So, we knew right out of the gate it's in Episode 1 that was going to be super important. The challenge there was to believably work with the camera and the actors. We had a motion base to help us with that. Walker [Scobell], who plays Percy, was able to get on the back of the Minotaur to be thrown around and to have to hold on and slide around, because there's rain on set. We did that on a volume stage. I always like to talk about the chimera in Episode 3, because that's just one of my favorite monsters a mashup of a lioness and a goat and a snake. The success of that really comes down to the fact that we were able to take an entire set and just paint it all black and use flamethrowers. The special effects guys came in and gave us proper elements, because it's a fire-breathing creature.The work done on environments by one of our trusted vendors up in Canada also stands out. All kinds of wonderful environments from Medusa's Cavern, which they did as a content for the volume, to all the great work for the Underworld. We had this great concept that the Underworld was going to be a massive cave on an almost planetary scale. And if you look at that, you're going to see that it's not sky. There are actual mountains up there and they have an alluvial flow. You get these lovely, almost spider-like outcroppings from each of the mountains that's buried in the mists.DS: The chimera was really well done. I especially liked how the catlike mannerisms were brought out.EH: That was done by MPC in London, and it was their crown jewel. They also did some work with Alecto, but this is where they really shined. Its in the gait you can tell that's definitely how a lioness walks. They just hit the nail on the head. But its also the eyes and how it opens its mouth. We added a little tongue, a snake tongue that comes out, but even that felt feline. It's really cool, I like that. DS: Tell me a little bit about the LED stage work. You and ILM made fantastic use of the LED volumes to create a lot of big environments, but there's also a lot of intimate work within that.EH: Jeff White, the supervisor at ILM, was the one who was heading up all the stagecraft work. They were the right choice to build the volume stage for us and to do the content. They did the content for all but one of the sequences, and a lot of the show's success comes from those volumes. The things that were shot on the volume are juxtaposed with scenes that are outside, that take advantage of real light in ways that the volume can't. That came from ILM telling us, "Don't do everything on the volume. Let's pick and choose the things that make it shine." And that's what we did.One scene that was really remarkably well done is when Luke [Castellan, a son of Hermes] and Percy square off. It's kind of broken into two parts first they're training and then they fight for real. That's on a volume where we had a lot of trees that were live action on the volume stage and then, in the content, you had the same kind of trees. And there was a fireworks show going off above their heads that lit the whole place. It wasnt really a big thing, but the two scenes that are in that particular volume are so successful. You always try to do a little bit of something that's live. We had puddles that would get the reflection from the volume; we also shot plates of water, actually in Southern California, and used those on the stage for the ocean that's out in the distance. It was a nice collaboration, to shoot the scenes that made the most sense, and bring those to life with the volume.DS: Did you do any previs and, if so, what did you use it for?EH: Previs played an important role, as you could imagine. In the very first scene with Percy and Alecto in the fountain in front of the Metropolitan Museum of Art, we used it because we were really interested in knowing what shots we could do. It's not a complete circle, so it enabled us to understand when we're going to come off the volume, then we would maybe tighten up or push in or something. It helped us tremendously in figuring out what we could actually do to stay on the stage.DS: What about postvis?EH: We did do a little bit, but, by and large, the planning goes into the volume and such. Its about things like whether the trees in the background are blowing in the wind. And, if they are, do we have some trees on the set that are going to be blowing in the wind as well? Does that all work? What does the rain look like? It's about testing the color balance between the foreground and the content. It takes a lot of time to build something, but essentially we're doing shots that would normally take 20-some odd weeks in post. We're just doing all that up front so that it looks right when the camera rolls. DS: When you look back on the season, was there one big challenge that stands out from everything else?EH: I guess I would go back to the Minotaur, because its a perfect example of the general challenge we faced. The show had to be accessible to young kids and to older viewers. We wanted adults to be able to watch it. So, it couldnt be too scary for an eight-year-old, but it also couldnt be too silly that adults say, "Well, you watch it and I'm going to go do the dishes." We wanted it to be a family event, where parents were engaged, as well as younger kids.And I think we succeeded, but it wasn't easy. In the case of the Minotaur, we went back and forth on whether close-ups of it roaring over Percy were too scary. We didn't want it to look like a zombie. [Executive Producer/Creator] John Steinberg said to me, "It has to have a little bit of teddy bear in it. Just always keep that in mind."From a technical standpoint, the biggest challenge might have been a sequence that took place in the area near the pit of Tartarus. We had to shoot it on a stage, and it was supposed to be out in a vast, hilly desert. And so, you got really close to the sky that was created by the DP. I was really scared that that was not going to look like we were outside.That it worked so well is a testament to Jules [OLoughlin], our DP. He said to me, "I'm going to go really soft. I'm going to help you out as much as possible." And I remember telling him later, I did not think we were going to pull it off, but it definitely looks like you're outside." I think to some degree it was helped by color, but it really did work. Sometimes you think you're going to have a real hard time with something, and then youre pleasantly surprised by the outcome. Jon Hofferman is a freelance writer and editor based in Los Angeles. He is also the creator of the Classical Composers Poster, an educational and decorative music timeline chart that makes a wonderful gift.