Researchers at the University of Bournemouth in the U.K. have created a set of tools to make the skin and muscles of animated figures move more realistically.

Traditionally, animators start creating characters by drawing their external appearance, adding details such as how muscles look when flexed on the basic design. Animators prefer this skin-based approach because it's the most intuitive and because adding muscle details to a form that you already drawn is quite simple.

But it's less realistic, the character can look "fake" if the skin does not correspond exactly to the muscle behind.

Building the muscles first and then layering the skin on top of them creates more natural-looking characters, though it requires an advanced knowledge of human anatomy (even if the character is not human, our eye is used to that).

Jian Zhang and his colleagues have developed an algorithm that begins a design with the muscles under the skin while the animator focus on the external appearance, while writing the rules on the structure of major muscles.

When a body part is flexed, the animation algorithm makes the muscle expand or contract and the skin react accurately using information about the muscle's shape underneath the skin.

Zhang began by looking at the muscle groups that most often cause skin to move, including the shoulder, neck, arms, thighs, and calves. Then he analyzed the muscles' shapes and simplified them into ellipses. This simplification enable the animators to make realistic movements without having a deep knowledge of anatomy, as well as conserving the computational power required by the process.


In the figure on the right, the major muscles on the left half of its body have been extracted using the researchers’ technique. The muscles are used to deform the skin surface when the character is animated.