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Behind the scene for Laika's 'The BoxTrolls'
Posted on Oct 03, 2014 at 11:40 am IST
LAIKA is one of the powerhouse studios of stop motion animation, captivating viewers with films such as a Coraline, ParaNorman and now The Boxtrolls, directed by Graham Annable and Anthony Stacchi.
LAIKA is one of the powerhouse studios of stop motion animation, captivating viewers with films such as a Coraline, ParaNorman and now The Boxtrolls, directed by Graham Annable and Anthony Stacchi. But what audiences may be surprised to discover is that the studio also relies heavily on visual effects techniques to help realize its features. From fully CG characters to crowds and environments, LAIKA now approaches animation in a hybrid manner whilst still preserving is renowned stop motion aesthetic. We spoke to LAIKA co-visual effects supervisor Steve Emerson, CG supervisor Rick Sevy and CG look development lead Eric Wachtman about their process.
“The big thing about our work is that we’re creating computer generated images to support practical stop-motion assets,” explains Emerson, who shared visual effects supervision duties on the film with Brian Van’t Hul. “First we’ll get a script and basically what happens is there’s an in-house story team here at LAIKA, and they’ll work drawing the whole thing out, they’ll create all the animatics, they’ll put all the temp dialogue and sound in, they’ll cut the entire thing together.”
With this rough cut, the film’s department heads review how the shots will be executed - almost always a combination of stop motion animation and CG and compositing approaches mixed in. “Visual effects will touch every single shot in some capacity on a LAIKA film,” says Emerson, “even for doing quality control, dead pixels or images.”
Practical solutions will be considered first. “One of the things that makes LAIKA so distinctive and so special is just the amount of effort that goes into first and foremost the animation with the puppets,” notes Emerson, “and even beyond that the incredible craftsmanship that comes out of our art department and model shop and the guys that are out there building all these physical environments. What ends up happening inevitably is we’ll hit some sort of block, where it’ll be something like water, liquid or typically something very difficult to do with stop motion - particulate effects like smoke, steam or fire.”
Although these elements highlighted by Emerson can sometimes be achieved practically (and they often are), the visual effects team is also able to generate them and help tell the story required. Sometimes a CG route is also taken for time and resource reasons. “Our typical quota for animators is something a little over two seconds per week,” notes Emerson. “We have approximately 50 stages that will be actively animated on during production. There’s only so many puppets and so many sets to go around. Inevitably as we get towards the end of a production, we just start running out of resources, and certainly that’s when they come to us, and they start leaning on us and start re-creating a lot of the physical practical assets out there and doing it all photo-real and picking up plates with greenscreen.”
So how does LAIKA replicate its practical puppets in CG? Interestingly, the visual effects team follows many of the processes that the puppet team follow in bringing the characters to life. “We’re creating the same materials that they make,” says Emerson. “An example would be the hair on the Boxtrolls, which was hemp. It wasn’t just about creating photorealistic hemp for hair, it’s also very much about how do they layer that hemp when they create the hairstyles. It was having them teach us so we could re-interpret what they were doing for the digital world.”
“They wrap the hair around the wire and then it’s posed,” adds Sevy. “So we give the same controls to our animators, we don’t run dynamics on the hair. We do run dynamics sometimes on the cloth, but just to get it started, maybe to get some keys and from there it’s posed.”
Similarly, for animation, LAIKA ensures the CG versions of the characters exhibit the same stop motion look as can be achieved for real. “One of the unique things about our rigs is that we try to build them just like the armatures are built,” says Sevy. “No spine stretches, no arm stretches. If they’ve got a ball socket here and a hinge here we animate them like that. Our puppet rigs match their physical armatures.”
For facial animation, too, the CG team marries its facial rig with the one developed to craft multiple facial piece replacements for the physical puppets which are printed with a powder-based color 3D printer. “We’re working with the rapid prototype animators that are doing all the physical facial animation,” says Emerson, “and they’re setting the looks in terms of those expressions for those animators on our side and beyond that when we do have 20-30 standard expressions in addition to the phonemes.”
That same stop motion approach exists even for crowd animation, something that might be considered optimal for a CG effect. LAIKA’s effects team typically added in additional Boxtrolls and other characters to scenes in the film, all the while ensuring that the hand animation style remained. “I remember when we first started putting together some of these crowds on ParaNorman,” recalls Emerson, “we were looking at the stop motion aesthetic in terms of animation on a technical level. What is it that makes it look like stop frame? We did all kinds of stuff where we messed with animation curves, we pulled frames out. Ultimately what we learned going through that process is that it’s not anything that’s technical, it’s a creative eye thing. We’re fortunate that the keyframe animators we have in visual effects - a lot of them have stop motion backgrounds, so they’re able to consistently deliver that to us.”
LAIKA did experiment at first with a Massive solution for crowd work, but soon realized that a full AI crowd system was not necessary. “Our shots were pretty short,” says Sevy, “so we could get away with, ‘Here’s a bunch of characters around a market stall, let’s animate them for 200 frames, and bring them together with different walkers for keyframe.’”
What did help the team, however, was motion capture for some of the characters, cleaned up and augmented with keyframing. “We animate everything on 1s and they’re gunning for everything as a naturalistic look with the animation,” explains Emerson. “Again it goes back to when we were banging our heads against the wall trying to figure out what the stop motion look was, we thought maybe it’s not so much about pulling frames or tweaking curves, the guys across the street are gunning for something very naturalistic - let’s start there. And I think that was one of the big motivators for bringing motion capture into the mix.”
“For crowd scenes,” adds Sevy, “our rigger developed some layout tools that the modelers could use. The modelers laid out the crowds, these are the mocap cycles we want applied to them, then they just played with timings and off-set and layout until the art directors bought it. If there was a character that seemed out of place or close to frame, we would up-res it to a keyframe character and pass off to a keyframe team.”
The result is that in many scenes in The Boxtrolls are combinations of practical photography and CG characters. “There’s an iconic shot of the Boxtrolls standing fairly close to camera clapping on their boxes,” relates Emerson by way of example. “In that case, there are three practical and the rest were all computer generated. Typically the rule is that the hero puppets and hero characters are usually practical. When it comes to a crowd, those second row back are the ones that we do in CG.”
LAIKA utilizes 3DEqualizer to track a virtual camera for the shot. Notes Sevy: “Most people think, ‘Hey you’ve got the motion control move right, so why do you need to build the digital camera?’ But the mechanics of the whole arm - you get sag and things - so the move never happens the way you program it.”
“At times we also go in and have a photogrammetry step where we shoot other pictures,” adds Sevy. “It’s part of our camera solve step. We grab some other reference photos, string those together and pipe them through OpenCV to generate a mesh, which gives the CG animators a ground plane and environment they can animate their puppets on.”
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