Some things, you can’t train a toddler to do in front of a movie camera. Like hanging from a table by her teeth. Or catching a wooden spindle in her mouth, like a dog snagging a Frisbee.

Yet such occasionally outrageous behavior was central to the character of Sunny Baudelaire, the youngest of the three orphaned Baudelaire children whose Dickensian travails are the subject of the new movie “Lemony Snicket’s A Series of Unfortunate Events.” The movie is based on the popular series of children’s books by San Francisco author Daniel Handler.

So Industrial Light & Magic, the storied San Rafael, Calif., effects house that George Lucas built, was drafted to do what 18-month-old twin actresses Kara and Shelby Hoffman couldn’t pull off on camera.

Old Flemish masters

ILM couldn’t rely on traditional photorealism techniques for creating a digital replica because the twin actresses portraying Sunny are so young. Instead, the visual effects wizards, who are surrounded at ILM headquarters by Darth Vader and other futuristic movie props, found themselves drawing from the portrait traditions of the Flemish masters to create Sunny’s richly detailed computer surrogate. Sunny’s digital doppelganger would appear only fleetingly in the movie. Not that you could spot her.

In photorealism, computer-generated images play stunt-double for live actors. Laser scans often are used to capture the actor’s features or body proportions. That requires standing perfectly still, without breathing, for 38 seconds while the scanner revolves around the actor to record a three-dimensional image.

ILM shot hundreds of pictures of the children to capture every conceivable facial expression. These would later serve as reference as Murphy, a portrait-painter by training, set out to re-create Sunny on the computer.

Murphy shot hours of the world’s least riveting home video – capturing the toddlers eating, sleeping, running, playing. He’d seize on rare moments of calm, when one of the twins would drink a bottle, to zoom in on her eyes to record the precise thickness of their eyelids, the shape of her ears, or how her eye pupils dilated when she looked around.

Murphy knew in advance that he’d have to re-create images of Sunny biting objects. That’s the character’s defining trait – Sunny likes to bite. So he spent a day with the twins, videotaping them stuffing toys and other objects in their mouths – an activity that, unlike body scans, toddlers are only happy to perform.

Murphy would later rely on the images to create a model of Sunny in the computer that adhered to the baby’s facial geometry – the precise size and shape of the eyeballs, the length of her eyelashes, the thickness of her cheek, and her baby-fine hair that curls just so at the nape of the neck.

ILM needed to mimic Sunny’s unsteady toddler gait. But here, too, it encountered obstacles.

Light bouncing off balls

Visual effects houses often rely on a technique known as “motion capture” to record actor’s movements and re-create it later, in the computer. It’s a process by which an actor performs wearing a body-hugging suit with reflective balls attached to all the major joints. As the actor moves, infrared light bounces off the balls and the motion is captured by cameras and recorded by computers.

Toddlers, no matter how good-natured, can’t be expected to re-enact a performance in a motion-capture suit.

“It’s not like you can really direct their acting,” said visual effects supervisor Stefen Fangmeier. ILM relied on motion capture to a limited degree to accurately record the twins’ facial expressions, Fangmeier said. It placed 120 small reflective dots on the more outgoing of the Hoffman twins and used a baby wrangler, with a bag of toys and a demeanor not unlike the infant portrait photographer at Sears, to coax a range of reaction from her.

Endless photographs

To choreograph Sunny’s more intricate performances – the kind director Brad Silberling couldn’t hope to coax from the twin – ILM recruited body-doubles. Employees brought their preschoolers to play in little motion-capture suits for the cameras. One 3-year-old who was comfortable with the cameras was able to follow her father’s off-camera direction, yielding a valuable performance. Then, they adjusted the body’s proportions to match those of the toddlers.

That motion-captured performance provided the starting point for a scene in which big brother Klaus plays a game of fetch with his baby sister. He hurtles a wooden spindle at her, which Sunny jumps up and catches in her teeth. She turns and smiles adorably at the camera, spindle in mouth.

It would take ILM six months to complete the fleeting scene. The animators would literally sculpt it, frame by frame, from ones and zeros. As simulated Sunny’s head would turn toward the camera, Murphy would adjust the eyelids and eyes ever so slightly, one-24th of a second at a time, so it looked like the baby was staring into the camera. The eyes – usually a dead giveaway that strips a simulation of its reality – seem to sparkle with life.

“Years before I used to be a portrait painter, I’d have those challenges,” said Murphy. “Breathing life into inanimate objects. There are techniques that have been learned over the years by master artists.”

Others at ILM would invest months, digitally recreating Sunny’s Victorian-looking dress, with its layers of pink eyelet, patterned silk and chiffon. Another person would work exclusively on Sunny’s Pebbles-inspired hairstyle.

Getting the digital Sunny to look lifelike was only part of the challenge. Seamlessly blending an ersatz image into a real scene – with actual furniture and actors – is another hurdle.

Capturing the light

To accomplish that meant correctly capturing the myriad ways light illuminates a space and refracts off walls, furniture and other surfaces. And accurately recreating the play of light on Sunny’s digital stand-in.

ILM would apply a new approach to simulate the way light ricochets off objects in a room and picks up faint hues from the surfaces that refract it. It’s known as “global illumination,” and it’s taken years to be embraced by the visual effects industry because of the complexities of the calculations, the demand for powerful computers to do those computations and the lack of software tools to apply the math in a meaningful way.

Christophe Hery, research and development supervisor for the film, said visual effects specialists usually simulate light as if it streams from a single, direct source.

To capture the realistic, billiard ball nature of light bouncing off objects in the spindle-toss scene, ILM started by precisely recording every object on the set. The position of every camera, the location of every light and the placement of other objects in the room.

ILM created a three-dimensional mock-up of the set in the computer and insert Sunny’s digital image into the simulated environment. Then, it ran the calculations to re-create the way light refracted off a nearby mahogany table would give a slight bluish cast to the right side of her face.

“In our world, when we have to marry the images that we create on computer with real-world images, they have to be fully realistic,” said Hery. “This is visually stunning because it means you get a huge portion of the subtlety of what real-life could do.”