by Ian Failes, Spark CG Society
November 12, 2016
Doctor Strange: The magic of Framestore
Marvel’s Doctor Strange introduces us to a brand new sorcerer in the Marvel Cinematic Universe. And what’s a sorcerer without magic — evidenced in the film via astral projections, conjured weapons, the Cloak of Levitation and kaleidoscoping fractal environments. Behind many of these magical sequences was visual effects studio Framestore, working under overall visual effects supervisor Stephane Ceretti. In this Q&A, Framestore CG supervisor Alexis Wajsbrot describes how some of the studio’s magical sequences were achieved.
Can you talk about the astral projections of Doctor Strange and other characters that Framestore worked on?
Alexis Wajsbrot: When we came on board there were already hundreds of different designs and versions of this effect. So we started with a quite complicated effect where there was a lot of echo and magical cords inside the body. I think we very soon realized that it was taking away from the actor’s performance, and so we had to try and design something that looks cool and a lot more subtle.
It was actually very challenging because of course we’ve seen a semi-transparent character before, and we’ve seen some on Star Wars, we’ve seen some in ghost movies, so it was like, how can we make it new and subtle and cool but still new? In the end it looks like a semi-transparent character but it’s more complex than that. We had to be able to control the background, so through the character we are sometimes distorting, bleeding the background, maybe sometimes changing the color just to make sure that we can see the characters correctly.
We had to deal with a second challenge in 2D to be able to make them feel like they are emitting light. And of course because they are emitting light we had to light the environment from them. When the environment is CG, it’s relatively easy. But in a lot of our cases the environment is in plate, and so we had to model it and track every little prop so we can have a path. It was just too hard to do in 2D, so we did it in 3D where we are actually modeling the environment and tracking the environment.
There’s a particular shot of the Ancient One putting Doctor Strange into that world, and he falls backwards and you see multiple versions of him. How was that done?
Alexis Wajsbrot: They shot an element on greenscreen of Strange, and fortunately he’s moving quite a lot backwards on the shot and the greenscreen element you really felt the layers, and so we decided very early to switch to a full digital character so that we could control the fractal side of it. And then we had the system to generate his echo. We have a core simulation and a half simulation, and on the frames we decided to do the echo to duplicate him. We had the tool to duplicate the character and slow it down, to slow down his core simulation and slow down his half simulation.
Let’s talk about the Cloak of Levitation, how did you give that the right personality?
Alexis Wajsbrot: In most of the shots, the cloak is really playing a key role as a character. We have a sequence where he discovers the cloak and he starts wearing it for the first time, and we also have a sequence where Kaecilius and Strange are fighting and the cloak is going to help Strange during the fight. The costume department did such a great job by designing the cloak. It’s a very, very complicated piece of cloth. He has his own life and a personality of a soul, but he can’t be too cartoony. So you need to have the normal dynamics of a cloak.
In the past we would have modeled it using a traditional tool. But on Doctor Strange we decided to use a different piece of software named Marvelous Designer, which is used in the fashion industry. You model a piece of clothing using patterns, exactly the same way that the costume department does it. So we actually asked for the pattern of the cloak. And I think there were something like fifty patterns to make the cloak, and so even if it’s just a cloak it’s still quite complicated, still made of lots of design patterns.
Marvelous Designer is a tool that you model in 2D with, just by doing the pattern, then you specify how it’s all connected, and then you simulate it on top of the character. And so all of the details that you get in your models are actually true wrinkles and cloth movements that you are simulating.
In that fight there’s also a bunch of magic and weapons and shields on display. Can you talk about these?
Alexis Wajsbrot: Well one thing we had to design were the whips which are made of sparks, and the reference was long exposure photography. And, in the same way, we had to do the gateway, the way that Strange can go from one place to another very, very fast, like almost teleportation. And he is going through this gateway which we had to do this gateway of sparks and design this effect as well. They filmed that with an actual LED light on the set which helped with interactivity.
How were the fractal and ‘Mandelbroting’ changes to the interior achieved in the sanctum fight?
Alexis Wajsbrot: The first thing we had to do was model the environment to a very great level of detail. I think it was hundreds of props first, baths and gardens and paintings and all kinds of different chairs, sofas, everything you imagine, we had to model. All these sets are incredibly detailed, so we went on set, took millions of photographs and to scan everything as directly as we can in terms of texture and scanning.
I also went to my lead rigger and said, ‘Let’s give full control to the animator and let’s just create one controller on every single piece.’ And of course the wooden floor would need to be split and each piece of would distorted, and so we managed to create a rig with over thirty five hundred controllers, and it took just a full night to build. So when I opened that I knew very early on that it was going to be impossible to do it like that because there were thirty five hundred controls to deal with!
So we decided to do another workflow, a new workflow, a brand new pipeline at Framestore to do this shot, which was to give the ability to animators to rig up the set the way they wanted. We created a toolbox for animators where they could select any piece of geometry during the set. Instead of loading the rig traditionally, they would look directly at the model and select anything in the model and be able to rig it with different tools. It meant they would be able to move the pivot, to rig it, and of course it would then follow into our pipeline. So when they published the animation it would publish a rig, and we would be able to complete the shot like it was normal animation.
That was just the first step of the Mandelbrot effect. On top of that we have what we call the true Mandelbrot effect. So this was done by the graphics department in Houdini. So we implemented toe Mandelbrot function in Houdini and they were converting everything into a volume in order to be able to apply this Mandelbrot pattern. The problem was, in order to be able to generate the right level of detail, as in converting the whole set into a volume, applying the Mandelbrot and then rendering that back was very, very heavy. So we decided actually to also create a new shader for Arnold which adds the Mandelbrot function, and applies the Mandelbrot function at render time.
All images and clips copyright 2016 Marvel.
|Ian Failes is a Sydney-based writer specializing in visual effects and animation. He also collects memorabilia from the film Speed. Follow him at @vfxblog.|
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