Rigging Actors for Reactions, Choreographing Fractals, and Finding References for the Film's Trippy Look

With Doctor Strange, Stéphane Ceretti has received his second Oscar, BAFTA, and VES nominations; his first nominations were for leading the effects on an earlier Marvel film, Guardians of the Galaxy.

Ceretti began his career as an animator and CG supervisor at BUF in Paris and became a VFX supervisor there for The Matrix Revolutions, The Matrix Reloaded, Batman Begins, and Harry Potter and the Goblet of Fire, among other films. More recently, he was visual effects supervisor at MPC for Prince of Persia: The Sands of Time. He became overall VFX supervisor for the Wachowski siblings on Cloud Atlas, and, at Marvel, an additional VFX supervisor for Captain America: The First Avenger. Doctor Strange is his 22^nd film.

In addition to the Oscar and BAFTA nominations, crews working on Doctor Strange have received six VES nominations, and the Industrial Light & Magic crew that created New York City won “Outstanding Created Environment in a Photoreal Feature.” ILM artists also received an Annie award for the Mirror Dimension in Doctor Strange.

Directed by Scott Derrickson, the Marvel Studios film distributed by Walt Disney Studios stars Benedict Cumberbatch as Dr. Stephen Strange. After losing the use of his hands in an accident, Doctor Strange learns mystic arts to heal his hands, but finds himself battling evil sorcerer Kaecilius (Mads Mikkelsen), Kaecilius’s followers, and Dormammu, a villain of a Dark Dimension where time does not exist. Ben Davis was director of photography and Charles Wood was production designer. The Third Floor provided visualization services.

Joining Ceretti on the Oscar nomination list are ILM’s Richard Bluff, Luma Pictures’ Vincent Cirelli, and special effects supervisor Paul Corbould. On the BAFTA list are Ceretti, Bluff, Corbould, and Framestore’s Jonathan Fawkner.   

StudioDaily: Why do you think your colleagues voted for Doctor Strange to receive an Oscar nomination?

Stéphane Ceretti: Doctor Strange is a big studio movie trying to be slightly different on many levels in terms of pushing the envelope — pushing the look and the visual effects to tell a story. Also, we tried to be original in the way we told the story. We did a blockbuster film that ended up with nothing destroyed. In the last 20 minutes of the film, we un-destroyed Hong Kong. That’s not the kind of visual effects storytelling we’ve seen during the last few years, in which we destroy cities and kill people. We tried to be slightly different and a little quirky. That’s why people were excited about working on the film, and I hope that’s why people like the visual effects, too.

How many vendors worked on the film?

We had about 10 vendors, but the main four were ILM, Luma Pictures, Framestore and Method. ILM did two big sequences in New York and Hong Kong. Luma was in charge of the opening sequence in London, a sequence in the cathedral where Doctor Strange uses his powers for the first time to bend the cathedral and change the space around him, and the end sequence with Dormammu. Method London was in charge of the Magical Mystery Tour when the Ancient One pushes Strange out of his body the first time they meet. Method Vancouver handled digital set extensions, environments, and magical effects for shots set in Kathmandu and a car crash. Framestore was mostly in charge of astral projection, the animation of the Cloak of Levitation, and a balcony scene with the Ancient One and Strange.

How many visual effects shots?

1,450. That’s not a huge amount. On Guardians, we had 2,300. But the complexity on Doctor Strange was very high, technically and conceptually.

What was the brief for the visual effects?

I first met with Scott Derrickson, the director, in September 2014. He was still writing the script, but he had categorized scenes and created folders with for us with lots of images — photography and paintings of optical illusions, kaleidoscopic stuff, long time exposures, light paintings for the photo magic. We took that onboard with Charlie Wood and worked together for two to three weeks, almost stuck in a room, to look at and add to Scott’s visuals, and create a visual guide for the film. We worked closely with Scott to develop the visual look.

What was your schedule?

We spent almost a year in prep. We had to do a lot of R&D and we previs’d everything before shooting. This was extremely complex to previs. It took a lot of time. We had a feedback loop between R&D, concept, visuals, and the script being written at the same time, so it was an interesting process. We started shooting on November 4 and the movie released in November 2016. We had only five months for post.

Where was it filmed?

In London at Longcross [Film Studios]. We also had a location shoot in Kathmandu, and aerial photography in Kathmandu and Hong Kong, but Hong Kong was shot in London. They built a street that we had to animate un-breaking itself. We shot in New York for four days, but once they start chasing each other, it’s green screen. We had some builds — some extensive sets for the temples in Kathmandu on sound stages — but we shot a lot on green-screen stages.

Since the environments in many shots would be digital and animated, how did you give the actors a sense of where they were?

It was essential to capture the actors’ reactions with a fair amount of physical stunts and effects. So we worked with previs, Paul Courbould, special effects, and the stunt people to come up with ideas for rigs so the actors could react to the moving environments — to what would be around them.

We had actors on treadmills that moved up and down so they could react to a moving wave in the environment.  And for the Magical Mystery Tour we had a really complex rig. Benedict [Cumberbatch] was in an arm that could spin in many directions. It was driven by computers using previs data and was a big challenge to engineer. Computer data also drove the lighting and camera. We had to make sure it was safe — make sure Benedict wouldn’t be hit by a camera spinning around. He was amazing. He spent three days spinning in that rig.

For the chase in New York, Charlie (Wood) built some gantries and a little bit of tarmac here and there, but we had to replace much of it because we had to animate the sets.

We shot Hong Kong in reverse. We had to shoot multiple actors going forward and backwards [simultaneously]. All the destruction had to be shot in reverse with motion-control cameras. Everything was interdependent. All the buildings destroyed were CG and the actors couldn’t see them. They’d ask what just happened and we’d try to answer. We had detailed previs so they knew where to look, and we showed them concepts. I spent a lot of time with the actors to be very thorough, and they were very clever actors.

Shooting the film was really difficult. Every shot was a puzzle.

What camera did the DP choose?

For most of the film, we used ARRI Alexa 65, the new large-format camera. We knew we had to do an IMAX version — 67 minutes. These cameras are amazing digital cameras. The depth of field, the resolution, the color rendering. Ben [Davis] pushed for them, and they are beautiful.

What did you reference for the effects? They’re pretty trippy.

Totally. The first Doctor Strange comics were done in the 60s and 70s, and they have these psychedelic images. I don’t know what they were eating, drinking, smoking at the time, but they have crazy shapes and colors. Scott [Derrickson] referenced that all the time. We tried to be faithful to them with a modern version. We also looked at the movie 2001, [and] at trippy stuff on the Internet, color palettes, textures, and a lot of fractal simulations. We looked at the way objects evolve and change, the mesmerizing effect of fractals, at optical illusions, and at kaleidoscope images. We had tons of ideas from everywhere. The iPhone game Monument Valley and Escher’s perspective and optical illusions influences the New York chase. These effects were all about serving the story, though.

Did you try to ground the effects in reality?

We tried and not-tried at the same time. We went quite far in terms of changing the world. But the way to start is to ground with reality. We use things from the real world and then have them behave in different ways. ILM built a huge amount of assets for New York and Hong Kong. The buildings are real-world buildings that people can relate to, but we make them behave differently. In New York, they had to bend in different ways.

Portals begin with sparks and fire. But, bit by bit, we get crazier and crazier and take the audience from something they know until at the end they’re in a 3D kaleidoscope. The Dormammu sequence could get crazy because it wasn’t going against the story. It helped the story. It was what people expected. The fans know Doctor Strange is all about psychedelics.

Did you use cartoon physics?

Every now and then we had to. Some of the stunts are too crazy. We used some wirework for astral projection, but in astral form the characters can move in ways humans can’t. So they have a little cartoon physics in them. But we had to find a balance to make sure the audience doesn’t get lost. At first, the astral forms were heavy, but that took us away from the emotional charge that the sequence between Strange and the Ancient One on the balcony had to carry. So we toned it down. They look like ghosts with a little effects and transparency on them. The astral form can do crazy things like go through walls, but it had to be simple to protect the sequence on the balcony. It had to be about the people not the effect.

How did you make all these crazy sequences seem believable?

The quality of the renders. We always try to be photoreal. Also, pacing, editing. And we always try to bring the actors into the shot. The actors are the audience. The way they react needs to be believable. That’s why we made such an effort to put them in these situations where they have to do physical things. It allows the audience to emphasize with them.

You mentioned fractals. How did the VFX artists make use of fractals?

The characters bend the world in the cathedral and even in New York to a degree. We referenced Inception for ideas. But they can go beyond and rearrange things at a molecular level. So we used fractals to give an organic feel. All the vendors had to do fractals, and they all had to have a consistency. Usually fractals are equation-based. We wanted to choreograph them, so we did some R&D work to make them manageable.

It was a multi-layered process. The artists did some basic hand animation to deform the buildings. Then they textured the buildings. Not just the surface. They had to build and texture what was within the 3D world to create internal materials, because once the buildings deformed we could see inside. Then they applied 3D fractals to the materials — the glass, metal, stone, wood — and made them behave in a fractal way. The 3D fractal deformations animated themselves using the materials and would grow, melt, and change. They created interesting shapes. It was mesmerizing and kaleidoscopic.

How did you maintain continuity?

We had a constant feedback loop between vendors so we could exchange tools and setups when we could and, when we couldn’t, they would look at things and try to replicate them. We had a short post time, so as soon as we got something close to approval we’d share it. Collaboration is key on these shows. We set up bridges between the vendors for sharing work from the start.

What was the best thing about working on this film?

It was that I felt like everybody was excited about it. There was an open door at the studio to try something different and the collaboration was exciting. That’s what I like to do — to inspire everyone to come up with ideas, do their best, and be proud of their work. We had so many ideas from so many people.

How long before release did you finish the last shot?

Two weeks before the premiere. It was a difficult shot in Hong Kong. I was praying in a church for it to get finished. I lit all the candles and prayed. We have to get it done. We got it done at the last minute and sent it to the 3D guys to convert it to 3D stereo.

What did you learn from working on this film?

I learned not to be afraid. I’ve done this before, but this film told me we could really do anything and be bold about it.

What’s your next film?

Ant-Man and the Wasp. We’re trying to do crazy on this one, too — our own crazy.