In animation, the illusion of life comes from the meticulous application of certain key principles. Among them, follow through and overlapping action stand out as crucial techniques that breathe realism into animated motion. These principles are essential for animators working on traditional hand-drawn projects, CGI films, or video games, making motion feel natural and convincing. When mastered, they add an extra layer of believability, allowing characters to interact with the physical laws of the universe—even if that universe is animated.
This article dives deep into the principle of follow through and overlapping action, providing insight into how these concepts can transform a simple animation into something lifelike and fluid.
Follow through is a fundamental animation technique used to simulate inertia, the concept that objects in motion tend to stay in motion unless acted upon by an external force. It refers to the natural delay that occurs when parts of a character’s body or object continue to move even after the main action has stopped. For instance, think of a superhero who leaps into the air and lands. Even though the character's feet hit the ground and stop, their cape or hair will continue to move slightly, trailing behind the main action. This "extra motion" helps illustrate the character's momentum and makes the scene feel more dynamic.
Overlapping action refers to the idea that different parts of a body or object will move at different speeds. In real life, nothing moves all at once. When a character swings their arm, the hand, elbow, and shoulder don’t move in perfect unison. There’s a subtle delay in the motion of these body parts, contributing to a more organic, lifelike movement. This action is especially important in character animation, as it gives the impression of weight and elasticity.
For example, when a character turns their head, the torso moves first, followed by the neck, then the head, and finally, the hair or any loose clothing. These overlapping elements create a smooth, flowing movement that feels more convincing than a rigid, mechanical motion.
Though closely related, follow through and overlapping action serve slightly different purposes. Follow through focuses on what happens after the main action has ended, illustrating how different body parts catch up with the central movement. Overlapping action, on the other hand, occurs during the movement itself, showing how various parts of a body or object move at different speeds.
Both techniques are about depicting the nuances of motion, but follow through tends to highlight how things settle after motion, while overlapping action demonstrates how movement propagates through different parts of a body or object. Together, they make animation more fluid and grounded in the physical world.
Pierrick Picault explains the two principles through the lens of 3D animation in this video:
In 1981, animators Frank Thomas and Ollie Johnston, who worked extensively with Disney, introduced the 12 principles of animation in their seminal work Disney Animation: The Illusion of Life. These principles are widely recognized as the foundation for effective animation, used to bring characters and objects to life with realistic motion and emotion.
Among the principles, follow through and overlapping action are the fifth, helping animators create sequences that mimic the physical properties of objects in motion. Other key principles include squash and stretch, anticipation, and exaggeration, which all work together to create the illusion of life. For a quick and engaging rundown of all 12 principles and how they relate to each other, check out Studio Binder’s video on the subject:
Incorporating follow through and overlapping action into animation is pivotal for creating fluidity and believability. These techniques relate directly to how objects behave under physical forces like gravity and inertia. They work alongside the other principles, such as squash and stretch, to ensure that even exaggerated or cartoony animations maintain a sense of weight and realism.
For example, Pixar’s Toy Story effectively uses follow through and overlapping action to give Woody's movements more weight and believability. When Woody gestures or runs, his arms and legs move in sync, but his floppy limbs continue to move slightly even after his main actions stop.
When animating characters or objects, it’s easy to focus solely on the primary actions—whether it’s a character walking or a vehicle speeding down a road. However, without follow through and overlapping action, these movements can appear stiff or unnatural. In real life, even the most subtle movements involve complex interactions between inertia, speed, and force.
For animators, the challenge is to replicate these laws of physics in a way that feels intuitive and creative. That’s where follow through and overlapping action come into play. They prevent characters from moving like rigid robots and ensure that every part of a figure behaves in a realistic manner.
By incorporating follow through and overlapping action, animators can achieve greater realism and fluidity. These techniques lend a sense of weight, especially in character animation, helping to convey different materials (like the stiffness of a wooden character or the fluidity of a cloth cape) and differentiate between cartoony exaggeration and grounded, lifelike movements.
The use of follow through and overlapping action also enhances viewer engagement. The more an audience feels that the characters are grounded in the world—even an animated one—the more they are likely to connect with the story.
To effectively implement follow through and overlapping action, animators must pay attention to timing, weight, and the subtle interplay of body parts. Below is a step-by-step guide:
Mark Masters goes through adding overlapping action to an animation in Blender in his video:
After blocking out the motion, animators should play back their sequence and tweak the timing of different elements to achieve a more natural look. Reviewing animation in slow motion can also help identify moments where follow through or overlap feels stiff or unrealistic.
While follow-through and overlapping action are key for achieving smooth and dynamic motion in animation, overdoing them can result in an exaggerated effect that feels unnatural or overly cartoony. Striking the right balance is essential to maintain realism without losing fluidity.
When applying follow-through and overlapping action, it's crucial to consider the weight and material of the object. Heavier objects will have slower, more deliberate movements compared to lighter ones, and failing to account for this can make the animation feel off or unrealistic.
Books like The Animator’s Survival Kit and Disney Animation: The Illusion of Life by Frank Thomas and Ollie Johnston are essential reading for mastering these concepts. Online resources, including animation tutorials on YouTube and courses from platforms like Animation Mentor, are invaluable for learning.
For those seeking formal education, many top animation schools like CalArts or Ringling College of Art and Design offer programs specializing in these techniques. Alternatively, online courses from platforms like Coursera or Skillshare provide flexible options for both beginners and advanced animators.
