Think back to your favourite video games and CG-animated movies. Ever remember seeing a character put on trousers or slip on a jacket? They might seem like mundane actions not entirely worthy of an animator's time, but the reason for their absence is actually more technical than artistic. While things like cloth, hair, and water are typically generated with physics simulations, character movement is animated manually. Getting the two different systems to interact naturally with each other is where the challenge lies.

Researchers from Georgia Tech think they've come up with a solution to the problem, designing a system that allows a virtual human character to put on various types of garments in a natural way. The system—which is discussed in detail in their paper "Animating Human Dressing" released earlier this year (PDF)—consists of three main components: a "primitive" action editor, a dressing controller, and a cloth simulator. The system works by feeding it a reference motion—usually via motion capture (mo-cap)—after which the user assembles a sequence of actions to describe the reference motion using the primitive action editor.

An example would be putting an arm into a sleeve, which the researchers say could be described as first aligning the hand with the armhole and dragging the cloth up the arm from the wrist to the shoulder. The primitive actions are parameterised building blocks for creating various dressing animations, with path planning algorithms considering the state of the physics-based garment only at the brief moments the team identify as crucial to completing the action.

"The closest thing to putting clothes on you'll see in an animated movie is The Incredibles putting on capes, and that's still a very simple case because it doesn't really involve a lot of physical contact between the characters and the cloth," researcher Karen Liu told Vice. "This is the problem we want to address, because generating this kind of scene involves the physical interaction between two very different physical systems... the hardest part is to compute or come up with the algorithms that control the characters. The character has to make the right decision on how he or she is going to move the limbs so it has a clear path to the opening [in the garment]."

As you can see from the video above, the researchers' work has resulted in far less awkward movements when virtual characters put on clothes. Currently, this new method has only been applied to pre-rendered animations, but it could work for real-time 3D as well (like in video games). But the researches have higher aspirations, telling Vice that its work could also be useful in the field of robotics.

"If you want a robot to achieve something in the real world there's lot's of real world issues that we don't need to deal with because we're doing animation," Liu said. "On the other hand, the nature of the task is even harder because we're dealing with a highly deformable object in a very constrained space. Imagine you're putting on a shirt. You're not trying to avoid collisions, you're trying to somehow understand the collision and use the information you get from collisions to make the right decision to move your hand along the right path."