Why is it that earlier movies with 3D computer-generated animation, such as The Polar Express or A Christmas Carol, left people feeling slightly uncomfortable, while The Adventures of Tintin: The Secret of the Unicorn has garnered praise for its looks?

Down to details: Animators must get the smallest detail right or their art becomes unsettling.

Mori’s concept of the uncanny valley is simple—as the appearance of an object becomes more human, our empathy for it increases, but only up to a point. Beyond that, the empathy drops sharply, and only slowly moves back towards the positive after reaching the lowest point—a corpse.

In early 3D work, the characters and models did not look lively enough, lacking fluid motion. The net result, of stiff characters with flat, unmoving eyes, and faces that lacked expression, is in line with the lowest point on Mori’s chart, a zombie.

This is why 2D animation could feature humans while 3D animation has largely been about toys, robots or animals. The 3D style is close enough to being human to fall squarely inside the uncanny valley, so 3D animation, as popularized by Pixar, stayed away from human protagonists that had been a staple of the Disney era.

The visual effects of The Adventures of Tintin have been created by Peter Jackson’s Weta Digital studio, which also created effects for The Lord of the Rings films, King Kong and Avatar.

Aside from Jackson and Steven Spielberg (co-producer and director), the film also has inputs from James Cameron and Robert Zemeckis, who have made a number of motion-capture movies.

Like the animation studios, Weta has also stayed away from creating humans, until now. So what exactly makes Tintin different from films like Mars Needs Moms?

Shiven Sharma, PhD in machine learning, the University of Ottawa, Canada, has been working on video games, where the same concerns about the uncanny valley are at play. He says: “As fidelity improves, from simple blocky polygons to textured faces, it continued to get better and better, but beyond a point, we aren’t able to recreate a person yet. The fine details are what give these things away. The eyes, and the small movements around the mouth, are hard to animate perfectly, as is flow."

While animation was moving on a different path, games continued to try and improve the look of human characters. Sharma says: “There are a lot of tricks that animators would use—such as having bald heroes or making them wear a helmet. This is because flowing elements like hair are very hard to show properly. This is also why the ‘space marine’ is such a popular design style—it’s an obvious exaggeration, and isn’t supposed to be real, per se."

Sharma says: “Our mind is more accepting of stylized representations. That’s why the Tintin movie looks so good. They’ve made photorealistic people out of the comic books. But they’re Tintin people—the way they’re shaded, and the way they’re proportioned, is all made to have the same visual style that Hergé created in the comic."

According to Sharma, by intentionally exaggerating some features and movements, the mind is able to accept that the image in front of it is not, in fact, human.

These visual tricks, coupled with the same motion-capture technology from Avatar, use a mind-boggling array of capture points to detect the most minute movement and translate that on to the screen for fluid animation of characters moving, talking or reacting to scenes and create a far more realistic world than other motion-capture movies have accomplished before.

Thanks to the huge advances in computer technology year on year, the processing power that can be thrown into carrying out these calculations is now at a point where small movements below the skin, such as the way muscles shift when a person walks or smiles, can be tracked.

In games too, Sharma points out, the character models are getting more detailed than ever before as computing power increases. Games such as Crysis, Uncharted and Rage have reached never-before levels of fidelity and each new game has been launched with photos comparing in-game graphics with the real-world objects they represent.

Given that both Jackson and Spielberg have been involved in video-game production, it’s safe to say they have brought a few tricks over to film-making, and might well have revived the motion-capture genre of movies along the way.

Interestingly, Hergé pioneered the ligne claire (clear line) art style that did away with cross-hatching and other attempts at realism, instead focusing on a cleaner art style that flowed across the page. Many others in the Franco-Belgian comic school, most notably Spirou and Asterix, would use this as well, so it’s only fitting for the Tintin movie to break new ground visually.