Digital Puppeteers

Coraline is the first stop-motion animation shot stereoscopically with a dual digital camera rig. Director Henry Selick recruited an experienced stop-motion crew in order to create a handcrafted effect for the film.
All images © 2008 LAIKA. All rights reserved.

Stop-motion animation and stereoscopy aren't techniques that audiences have ever seen combined before — that is, until Coraline, the latest feature from Director Henry Selick of Nightmare Before Christmas fame. Produced at Laika Entertainment and released by Focus Features, Coraline is the first stop-motion feature shot stereoscopically with a dual digital camera rig, and it screens in theaters equipped with RealD digital projection systems. For Selick, who adapted author Neil Gaiman's Hugo Award-winning novella for the screen, animating Coraline in stereo presented challenges he'd never faced before.

“Shooting 3D stereo takes some getting used to on many levels,” Selick says. “Aesthetically, what are your choices? How do you not wear out your welcome by doing it too much? Of course, you have a left eye and a right eye, so it's double the amount of information if you're compositing a background or adding some effect like steam. You have to offset it to match what you've shot. We knew we weren't masters of this medium, so we held back a lot.”

Visual Effects Supervisor Brian Van''t Hul''s team had to do considerable paint work in order to remove seams from the puppets'' faces where their eyes and mouths had been filled in separately. This seam removal was developed by Laika Entertainment using a combination of Silhouette and Apple Shake.

Selick enlisted an expert stop-motion crew — including DP Pete Kozachik and Visual Effects Supervisor Brian Van't Hul, both of whom he'd worked with on Nightmare and his second feature, James and the Giant Peach. Kozachik, an Oscar nominee for the visual effects in Nightmare, signed onto Coraline in 2005, fresh from photographing Tim Burton's stop-motion feature The Corpse Bride. Van't Hul, who won a visual-effects Oscar for Peter Jackson's King Kong, eagerly reunited with Kozachik and Selick.

“Henry wanted a film that didn't have effects that screamed ‘CG,''” Van't Hul says. “He wanted Coraline to feel handcrafted.”

Kozachik recalls initially being skeptical that they could pull this off in stereo. “My first response was, ‘It's like Smell-O-Vision. We'll have to dumb down the look of Coraline to make the trick work,''” he says. “But I quickly changed my tune upon visiting Lenny Lipton's company RealD. Lenny showed that the technology was not like it was for Bwana Devil back in the day. We went to his place and saw that this was something we could use as a tool, like color or contrast or camera motion. We camera guys not only have to embrace it, but get smart about it so we can toot the horn every which way and not just blow the high notes.”

The DigiCel FlipBook application allowed Director Henry Selick to create shots that produce a surreal feeling when Coraline enters her other world.

Finding a camera system to actually shoot Laika's 9in.-tall puppets was another matter, however; live-action camera rigs such as the one developed by Vince Pace wouldn't work. “That would be like having an SUV-sized camera on set,” Kozachik says. “Even if we'd had two tiny little cameras, the interocular distance would have had to be on the order of millimeters, not even inches.” He recalls going online and typing in “machine vision” and finding a 4K digital SLR camera developed by Redlake (and now sold by Princeton Instruments) that would allow the crew to shoot one frame for the left eye and then have the camera shift slightly to shoot that frame for the right eye. The Redlake camera previously had been used robotically to inspect factory parts, but it enabled Selick to shoot small puppets in close-up. This had the effect of helping audiences see the miniature sets of Coraline from the puppets' POVs.

“Stereo required us to put a little linear mover at the end of the camera to move it slightly left and right,” says Van't Hul, who served as DP on a dazzling circus sequence in addition to his visual-effects responsibilities. “Knowing that we'd be shooting with digital still cameras rather than film cameras, Pete could design and build smaller rigs because he didn't have the huge weight of a motion-picture camera. These smaller, less expensive rigs could get in and around our sets. Coraline provided a great opportunity to miniaturize things.”

Illustrating Coraline''s two worlds required different versions of familiar rooms in her house. Pictured: DP Pete Kozachik.
Photo by Serena Davidson.

Kozachik recalls the juggling act of the crew trying to use three dozen cameras. “At full tilt, we had close to 60 setups shooting at the same time,” he says. “Luckily everybody had walkie-talkies, and every stage had a number, so we'd know when something had gone wrong on Stage 11. I probably spent 10 minutes on every setup each day. I'd hired a really good crew of about 30 guys spread into seven or eight units. Each camera unit looked after themselves.

“[Our approach to image capture] had its problems in the amount of time it took to suck these gigantic images down through a hose. So in some ways, I think that cost us a little time. Our basic piece of software was an adaptation of a [DigiCel] FlipBook application that the computer-graphics part of Laika already had. Basically it was a flipbook for the animators. It takes the down-rezzed, black-and-white images from the camera and animators can play them back and forth and record and erase.

The Redlake camera enabled Selick to shoot the small puppets close-up and allowed the viewers to see the set from the puppets'' point of view.
Photo by Galvin Collins.

“The same application also did a couple of other things. It captured the real color beauty images, and it controlled the interocular device. It sent ASCII [American Standard Code for Information Interchange] characters to a motion-control system that moved the camera to the left or the right to shoot another frame.”

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The camera crew definitely got more efficient during 20 months of shooting Coraline, according to Kozachik. “Any shot involving a snorkel just brought us to our knees,” he says.

The system allowed Selick to design shots that would capture a surreal feeling when Coraline Jones stumbled into a world oddly parallel to her boring, real existence. “In some cases, we were animating the depth of field during the course of a shot, which was another thing that was great about shooting stop motion with a single camera,” Van't Hul says. “Using the same camera shooting the left and then moving over and shooting the right, we had infinitely small distances. That meant we could animate a shot as a completely flat, traditional shot and then all of a sudden we could stretch it out in front of you by animating that right eye to be gradually farther away from the left during the course of the shot. In doing those sorts of things, you need to be aware that at some point it can cause eyestrain, so you don't want them to go too far apart.” Fortunately for all involved, Laika had a full stereo theater nearby where shots could be reviewed within minutes of shooting.

When Coraline first discovers a tunnel to the other world, a shot shows the tunnel stretching before her. “The interocular distance is also being animated. It starts sort of flat and then gets deeper and deeper, like the Hitchcock trombone shot [from Vertigo].” Van't Hul says. “We're zooming and tracking at the same time, using stereo in the same sort of way.”

Coraline's other world was conceived to be more colorful and stereoscopic than her grayer real world, like Dorothy in Oz vs. Kansas. Depicting Coraline's two worlds required different versions of familiar rooms in her house. “We had about nine special sets of her kitchen that only worked from one camera angle because they were built in this squashed, forced perspective form,” Kozachik says.

This created some interesting challenges for Van't Hul, as when Coraline falls asleep in her other-world bedroom and later wakes up in her real-world bed — revealed during a single camera move. “We had to warp and distort plates to make two physically different sets line up,” Van't Hul says. “That required a lot of tracking and shooting things as separate passes that we could cut and paste.”

Van't Hul's team used Autodesk Maya and Science.D.Visions 3D Equalizer for tracking and Apple Shake for compositing. They also used those tools to track in practical elements such as dry ice, which suggests foggy atmospherics. “We had a team of compositors warping and bending those fog elements using Shake,” he says. “In stereo, you have to nail things spatially or it's a dead giveaway.”

In addition to doing extensive roto work to erase the animators' rods from the puppets, Van't Hul's team had to do seam removal on the puppet faces where the eyes and mouths had been replaced separately. Such paint work is difficult in 3D, says Van't Hul. “If something isn't painted the same with the right eye and the left, you get a weird shimmer,” he says. Laika developed a method for seam removal using a combination of Silhouette and Shake.

An all-CG approach was used only to previz complex sequences in Maya, which enabled Selick to cut dynamic sequences in low resolution. “We used the previz to line up the camera,” Van't Hul says. “It saved us a lot of time on set.”

“All the help that we get from digital tricks and fixes allows us to do better work. But it's not easier,” Selick says. “In the end, it's like the original King Kong. You're touching a puppet and then taking your hand away.”