In the maze of offices at Pixar’s Emeryville, California, headquarters, the lighting section stands out. Overhead bulbs are dimmed—all the better for viewing nuanced effects on computer screens—except for a string of gentle white lights at the front, illuminating the dark blue walls. Sharon Calahan, the director of photography for Pixar’s upcoming movie, The Good Dinosaur, has an office nestled in the corner. Calahan is attentive and soft-spoken, warm and smiley under a curtain of bangs. It’s easy to picture her in the mountains, where she spends all her vacation time painting lighting studies of trees, valleys, and skies. A small stack of canvases leans against the wall beside her desk.

Spend time at Pixar and you’ll hear a regular refrain: The famed animation house wants its films to seem more like live-action flicks than cartoons. Executing that pursuit falls to crew members like Calahan. Though she deals mostly in pixels—she’s one of the rare DPs whose entire body of work is computer-generated—it’s still her job to build a believable (and believably lit) world.

Calahan thinks of each new project at Pixar as a unique stylistic challenge. Ratatouille was “soft and warm and romantic,” she says; Cars 2, which she worked on next, was “a guys’ film with shiny metal.” With The Good Dinosaur, out Thanksgiving Day, Calahan got to spend time in her happy place: open, natural landscapes.

The movie is set in a world where the asteroid that wiped out the dinosaurs never struck and prehistoric creatures live on Earth with people. It’s the story of Arlo, an apatosaurus who gets lost and on his journey home befriends a human named Spot.

When the director of The Good Dinosaur, Peter Sohn, told Calahan he wanted the film to have a rugged, pioneer feel, she already had a place in mind: Jackson, Wyoming, where she’d spent time painting landscapes. Calahan joined the crew there on a scouting trip so they could soak up the region’s treacherous terrain, severe weather, and expansive sky. Starting north, they boated down the Snake River, explored canyons, rode through the Targhee wilderness, and gazed at the Milky Way (sans light pollution).

“Pete hadn’t spent much time in an area like that, and I watched him discover that world: how harsh it can be, how the weather turns on a dime, how rugged everything is, how short the growing season is, and how much early settlers there must have struggled to survive,” Calahan says. “It inspired him to find the tone of the film. He wanted that big-sky feeling—when there’s low moisture in the air, you really can see for miles.”

Calahan’s day-to-day contributions on a film are similar to those of a live-action director of photography. Early in preproduction, she looks at storyboards and composes paintings to inspire tone, feel, and the general look of the film. From there, she pitches ideas, asks for shots to be recomposed, and explores lighting options for each scene. Her weeks eventually turn into a flurry of art and set reviews, lighting walk-throughs, director check-ins, color grading, and effects critiques, all while overseeing her nearly 50-person lighting department for this movie.

As inspiration for production on The Good Dinosaur, the crew watched dozens of films: classic Westerns for mood and story; Seven Years in Tibet and The Secret Life of Walter Mitty for scope and camera work; and Carroll Ballard’s The Black Stallion and Never Cry Wolf for tone. Because The Good Dinosaur is highly visual, with color and light playing a large supporting role, Calahan also revisited some of her favorite Russian landscape paintings, like the moody, evocative works of Ivan Shishkin and Isaac Levitan. “There’s a truth about their paintings that I like,” she says.

Calahan says the resulting look is authentic—but not exactly photo-realistic. “We want it to be believable that if Arlo fell and hit his knee, it would hurt,” she says of the titular good dinosaur. “That the water seems cold, that you can breathe the air and feel the wind.” But her background in fine arts taught her that not every detail is necessary: “I’m not trying to paint every blade of grass or every leaf. I’m trying to reduce things down to their essential elements and bigger shapes that hold the image together structurally.”

Because the film is set entirely outdoors—a first for Calahan—she had to ensure each scene would have a distinct look and feel. One solution was determining signature coloring and lighting styles: Scenes among trees dominated by brown and green hues are followed, for example, by alpine pools with a cool, blue palette. Calahan’s lighting in one moment might capture the feeling of a late afternoon; minutes later, a subtle change in intensity and shadowing has to telegraph the turn to dusk.

Calahan made compositional changes as well. Typically, CG films build out the foreground of scenes, relying on matte paint for the background. But because The Good Dinosaur relies so heavily on a sense of place, her team created individual volumetric clouds and used USGS data to expand the geographical detail. To add to that feeling of vastness, they chose wide framing, with more helicopter-style shots than normal.

After countless refinements from different departments, Calahan helped decide when scenes were ready to be cut into the film. “I’m trying to capture a certain emotion,” she says. “I want it to make me homesick, in a way.”

Though Calahan has been with Pixar since Toy Story, her foray into film was largely accidental. She studied advertising and graphics and then entered the television industry making commercials. From there, it was a slow evolution. “I kept walking through open doors,” she says. After a coworker joined Pixar, Calahan snagged an interview and was hired as a lighting supervisor.

Over her 21 years at the studio, the nature of Calahan’s work has changed. When she started out, creating light in a scene meant writing script code. Now, advanced user interfaces and improved design programs mean Calahan and her team can create complicated lighting faster—the saved time is invested in making subtler, more complex films. Calahan is still a rare bird in the film business. Few people share her title in the animation industry, and when the American Society of Cinematographers invited her to join its ranks last year, she became its first member to have an all-CG reel.

One of her sponsors for ASC membership, the cinematographer Stephen Goldblatt (The Help, Lethal Weapon), says traditional cinematography entails physical work on location, and that some society members initially didn’t understand Calahan’s process. “She has her own problems to deal with, technically and logistically, which just happen to be inside a studio,” he says. “The lighting, color, texture, how much light or how little light, the mood, the haze, the smoke are all introduced like in the work I do. She just does it with tools that simulate that infusion. What I admire in her work is what I admire in Vittorio Storaro’s work or any great cinematographer’s work—in the end, it’s irrelevant how it’s produced.”

Calahan hopes her acceptance might influence aspiring artists to follow her path, though it might not happen overnight. “It was something I’d dreamed about,” she says. “Change is hard. What I do is different than live-action, but there’s so much of it that’s the same. There’s still a newness to it all.”

GROOMING BY JULIE DY