Skrull transformations: inventing a new type of morph

All about ‘Captain Marvel’s’ shape-shifting Skrulls, and ponytails.

We’ve all seen some pretty good morphing and transformation effects in the last 20 years. So when Captain Marvel’s VFX team had to come up with a way of showcasing the shape-shifting powers of the film’s Skrulls, they were keen to find a fresh way to pull off the shots.

Production visual effects supervisor Chris Townsend, and Digital Domain’s Dave Hodgins and Hanzhi Tang, tell befores & afters about their new approach in particular for the Skrull transformations that occur on a Los Angeles beach as the characters emerge from the sea and merge into a group of surfers.

Chris Townsend (production visual effects supervisor): We sat down with Anna Boden and Ryan Fleck, the directors, and the studio, and said, ‘Okay, what is it you want? How do you want these to look?’ One of the interesting things was that they wanted it to feel very physiological. They didn’t want it to feel like a morph, per se. They wanted to understand that their skin was transforming, and bubbling, and changing, and this one character was becoming the other.

The transformation begins. Image courtesy Digital Domain. © 2019 Marvel Studios.

Dave Hodgins (Digital Domain visual effects supervisor): We looked at a lot of reference, a lot of nature like squids and octopus, and things that change color, and we looked at things that shed their skin and essentially morph, and we looked at time-lapse like mushrooms growing and slow-motion popcorn exploding. The initial discussion, too, was that you always went through Skrull forms, so if you were going from person to person, like two humans, you would have to go through a Skrull. I think ultimately in the transformations we never really did that. We were never going from a person to a person. We were always either going from a Skrull to a person or from a person to a Skrull.

The very first iterations were much more inspired by the American Werewolf in London type of transformation, where we weren’t really splitting the skin, and it was more of a color and shape change. We did quite a few tests of this, and some of the early ones looked a little bit more like a time-lapse of an apple drying out in the sun. You would get this wrinkle, and then it would essentially hydrate again and fill into the other face.

Chris Townsend: We did a lot of work on a particular look, and we got pretty far down the road. We got to a point where we said, ‘Okay, we think we’re just about getting there. What does everyone think?’ Then [Marvel producer] Kevin Feige said, ‘You know, it doesn’t feel specific enough for the Skrulls. It just feels a little bit generic, it’s cool and everything, and it works and it looks good, but it doesn’t feel different enough.’ So we went back and said, ‘Okay, well, then what can we do to make it feel more Skrull-like?’

The painful nature of the transformation was an important factor to communicate. Image courtesy Digital Domain. © 2019 Marvel Studios.

We came up with this conceit that one state stands there, the target, as it were, they are able to reproduce that, and they were able to organically recreate that body, and that it would ooze out from those grooves in the chin and in the face. So we were working a lot with trying to use those splits as our sort of signature effect.

Filming the scene

Hanzhi Tang (Digital Domain DFX supervisor): On the day of the shoot, Ben Mendelsohn came up with what he was going to do as Talos – he had a chat with the surfer girl, and she tried to emulate what he was doing as well, as best they could. They had a few practice takes during the day, and then when sunset came we had 20 minutes to do as many takes as possible, and they just picked whichever ones matched the best, Ben’s performance being the driving factor in this.

(L to R): Director Anna Boden, director Ryan Fleck, and Ben Mendelsohn (Talos) on set. Photo: Chuck Zlotnick. © 2019 Marvel Studios.

Dave Hodgins: We had ICT Light Stage scan data for the surfer, and then we had a photogrammetry scan for Ben Mendelsohn’s Talos in Skrull make-up. Then we looked to match the two disparate elements of the two characters. There was a lot of legwork, a lot of modelling and texturing and look-dev for essentially a one-off shot.

Hanzhi Tang: Luckily we did have a really good high-res scan of the girl, because we knew we were going to need a full-CG girl at some point. We thought we could get away with just sticking with the plate version of Talos for most of it, but we ended up having to do a CG version of him pretty much as well. So we shot that day at the beach, and I actually went back the next day when the camera crew had all gone and packed up, and I took an HDR with with a clean set, at the exact same time of day. That was one of the benefits of having the set 15 minutes down the street.

Dave Hodgins: One of the largest challenges – and we didn’t expect it to be as difficult as it was – was just getting everything to align and track on that shot because of the camera moves. They were shooting it at the end of the day, just as the sun was going down, so we didn’t have as much time as we expected to line up the two shots. We basically drove it off Talos’s performance, but then we shot her and used her plate, and then we lined Talos up to her plate at the beginning before we started transitioning.

Talos (Ben Mendelsohn) and his Skrull companions. Photo: Chuck Zlotnick. © 2019 Marvel Studios.

Hanzhi Tang: It’s a challenging shot because, if you look at it, you’ve got so much in the 90-degree pan, and the background is all just ocean so there wasn’t anything super stable to track to. We tried to put tripods in the water, and maybe some tennis balls out there, but with the waves and everything it was pretty much impossible to put any sticks that would actually stay put. We had at least four or five different witness cams; we had GoPros on the top of each of the main cameras, and then we had four extra witness cams to the sides, and we just tried to use it to help us do the track as much as possible. It needed to be tracked by eye, at the end of the day, just because there was a lot of guesswork involved.

Jumping into the transformations

Dave Hodgins: We would start by creating a plate where it was a 2D transition, kind of a cross-dissolve between the two plates where we start out on the Talos plate, and then it crosses over during the transition area to the surfer girl. The original transition was matching her performance, and then we were pretty far into the shot when we decided to bias the performance towards Ben’s performance. We basically biased it towards the Ben plate to get more of that sense of pain when she was transitioning. That’s where we were doing blend shapes between the two, the simplest form of the transformation. While that was all going on, in parallel the effects guys were getting started on effects sims just from an overall point of view. Once we had all the tracks and the animation in order, the effects team picked it up at that point and worked more on a shot-based approach.

Hanzhi Tang: We used Houdini for the effects simulations – there were tons of different sims, because it was an exploration of what was even going on in the skin, whether it was the skin splitting, or liquid coming out of it and then forming a new skin. I think we pretty much passed through everything but the kitchen sink.

Houdini effects simulations were employed to show the skin ‘oozing’. Image courtesy Digital Domain. © 2019 Marvel Studios.

In fact, the first two or three months were just exploring different kinds of effects. We tried particle effects and fluids. We tried to simulate what skin looks like if it was splitting open without looking too gross, and then once we had this buffet of different things we could do, we tried to come up with a cohesive language that at least made sense so that we could do the same thing. We wanted every transformation to make some kind of logical sense when we did it, in other shots and sequences.

Dave Hodgins: At one point there was a fluid that went over the top of the surface. For the splitting, we basically modeled the two characters with the same typology, and then we made an in-between character which was the surfer girl with the Skrull lines within the face, and then once that was published, we published curves along the lines for the Houdini guys to use to drive their simulation, or know where to split things along. And then it became a three-part thing where you have the initial splitting and the forming, and then that middle section.

The middle section was the most difficult part, because we got the splitting early and they liked that, but then we couldn’t figure out how to transition from that all the way back to her without it looking essentially like a 2D wipe. On her plate, which was the first one, it was a little bit easier because we had a lot of time since it was a fairly long shot to build up the transformation. On subsequent transformations, as we tried to use the same methodologies, we found that the faster the transformation was the more it looked like we were just going from one plate to the other. So as the show went on, we were trying to take what we’d learned but then have it happen much faster and not have it look like a wipe, or just a morph.

In this video above, Chris Townsend breaks down several of the film’s VFX challenges, including the Skrull transformations.

Skrulls with ponytails

Hanzhi Tang: For me, the highlight of the beach transformation shot is the hair sim. It just kind of happened halfway through our exploration. Originally, the actress had her hair tied back in a bun, just so that it was clear. But Chris Townsend said, ‘Well, why don’t you try keeping it as a bun, and then it kind of just drops and we let it fall down.’ And then it turns out to be this thing that adds this extra flair to the shot when the hair pops down.

Dave Hodgins: It took us a while to get the groom in order, and we had to modify our software to allow it to grow. We had talked about it a lot, and we were kind of dreading the hair shot. We were a little concerned about how this was going to look, how these strands would grow out. And the first pass through of this dropping hair that Chris had suggested, we were like, ‘Awesome.’

Hanzhi Tang: The thing is, I think the first few attempts at growing hair into a long ponytail looked like – you know when you extrude Play-Doh through one of those plastic things? It looked like that. But in the end, the ponytail with the bun actually helped solved that and made it look a lot more natural than we had.