“It was about honoring the work. We became comic archaeologists, studying 65 years of the strip," said animation supervisor Nick Bruno.

Team members at the Ice Age animation studio Blue Sky Studios were both excited and nervous when they were tasked with turning the iconic Charles M. Schulz Peanuts comic strip into a 3D motion picture, The Peanuts Movie, which opens Nov. 6.

Speaking Thursday at CGI confab Siggraph, the team inspired a clearly enthusiastic crowd of animation fans as it described how it translated Schulz’s subtle dots and pen lines — some of the world's most recognizable comic strip images — into the upcoming feature.

It also demonstrated that this was far more complex than it might at first appear. When the first tests didn't work, confirming early worries about the difficulty of the project, the team took a road trip to the Charles M. Schulz Museum and Research Center in Santa Rosa, Calif., and studied the archives while working closely with the Schulz family. Several members of the cartoonist's family were involved in the film's production, including the cartoonist's son Craig Schulz, who wrote and produced. The trip inspired director Steve Martino's new mantra: “When in doubt, go back to the comic.”

Throughout the Siggraph session's 90 minutes, the team showed and discussed early tests, prototypes and clips from the three-year journey toward creating the film.

“It was about honoring the work," said animation supervisor Nick Bruno. "We became comic archaeologists, studying 65 years of the strip.”

Character development started with creating the “hero views” and the “best versions” of the characters from the ‘80s and ‘90s drawings (as they have experienced subtle changes over the years). “But we discovered some interesting things," said Bruno. "Profiles are not the same as the front view. For instance, Charlie Brown's ears are in different places, so a 3D model couldn’t work." He called Snoopy a "Picasso," noting that nothing was consistent. For instance, a side profile of the pup had two eyes. The body represented the same issue; these are cheats. Schulz — known as “Sparky” — only drew the characters from six different head angles. So Blue Sky built the different heads as 3D computer models and used some snappy motions.

Elaborating on the animation style, animation supervisor Scott Carroll noted that the classic 2D animated specials were not particularly accurate; they had a handcrafted feel. “Typically, we would use motion blur, but we had to fill the gap with traditional animation techniques, using poses and snappy movements. And we were still hitting iconic poses.”

Some scenes use multiple body parts (i.e., legs and noses) to fill the gaps or motion lines (lines with the hand-drawn look), which helped bring Schulz’s pen line into the film — an important goal.

CGI supervisor Robert V. Cavaleri noted that effects were also tricky because they had to conform to a pre-existing hand-drawn style. Pig-Pen and his dust effects were one of the biggest challenges — and the dust still managed to contain the pen lines.

To train the animators, the team created a three-week crash course on the style that they dubbed Van Pelt University (after character Lucy van Pelt). That started with drawing Charlie Brown — which proved much tougher than many expected — and watching and rewatching the classic animated specials, including A Charlie Brown Christmas (which marks its 50th anniversary in December). A style guide informed details, including eye- and nose-direction charts.

Food was used for references. For instance, a side view of a foot was the shape of a baguette, while the bottom of the foot had more of an egg shape. This vocabulary also informed production design, with clouds in the sky resembling popcorn.

"It had to feel like you were looking at the strip, with the spontaneity [of drawing]," said art director Nash Dunnigan of the production design. “We also achieved a nice level of simplicity, so nothing overpowered the characters.”

Other challenges included the creative choices made for the stereoscopic 3D version of the film. These used varying amounts of depth. For instance, in Charlie Brown’s world, the 3D is more constrained. “For Snoopy, we didn’t do that, as his world is more fantastic, such as in the flying sequences," said Cavaleri.

Carroll summed up: “Our big lesson that we took away from this: If you have faith in your creative team, you can take on big risks.”