Doc:Tutorials/Animation/BSoD/Principles of Animation/Principles/Follow Through and Overlapping Action

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Blender Summer of Documentation: Contents | Manual | Blender Version 2.41

[edit] Introduction

[edit] What

[edit] Follow Through

When a character stops moving, any appendages attached to its main body will not halt immediately. Ex: a dog with loose skin and flews, tail and fallen ears. As it comes to a sudden stop, its looser parts keep on moving for a very short while, each stopping at a different time.

That's Follow Through: the continuation of movement that happens with the looser parts (appendages) after the main body has stopped.

[edit] Overlapping Action

Back to the example of the dog: while it was running, its looser parts also had some freedom to move on their own, they do not stick to the body. When the dog changed direction, these parts continued on their previous line of motion until the were pressed against its body or pulled by it.

Overlapping Action is the superimposition of motions of the carried parts over those that carry them.

[edit] Drag

Tired of being used in our examples, the dog decided to quickly go somewhere else. As its main body and four legs started to move, those same looser parts took a little while to follow. They “dragged” behind the rest.

Drag is what happens with appendages of a body when it starts to move: they take a little time to accompany the movement.

[edit] Summing up...

All three cases are about the motion of carried parts in relation to the main ones that pull them around:

[edit] Why

Because that's what happens. One of the things that bothered Walt Disney at the beginning of the golden age was how characters in their animations simply halted after each action, all parts of their bodies, garments and accessories stopping at the same time. He complained about how unnatural that looked, that things do not come to a stop all together, it first happens with one part, then with another, etc.

Not knowing how to properly deal with the halting problem, they studied it and finally compiled the related sets of techniques known as the Follow Through and Overlapping Action principle.

[edit] How

[edit] The categories

In “The Illusion of Life”, the authors describe five main cathegories that were identified:

1. Character with appendages (loose clothing, long hair or ears, antennae, etc.) will have these parts still moving for a short while after the torso has stopped.
2. Bodies don't move all their parts at once. They stretch and squash, parts turn, pull and push working against each other. When one stops others may still be moving, like arms swinging after the trunk has halted. To clearly show a character's attitude and feelings her head, shoulders and trunk may stop at the same time, since those are the parts an spectator "reads" to know how they feel. Other parts may take longer to reach their "rest position" for the current pose -- remember, we're talking about settling down at each pose, not final, complete stops.
3. Parts with more tissue like cheeks, bellies, etc. can move noticeably slower than the bones beneath them. This is called "drag" and, well executed, it helps a lot making shapes look solid and organic, life-like.
4. This is fun! In another sense, "follow through" can also refer to what happens to a character after an action. It deserves its own subsection, check it right after this one.
5. The Moving Hold. TODO

[edit] The torso and the hips

The torso is the body minus the head and the limbs (arms and legs). It's also called trunk and main body and it is where most of our mass is concentrated, so it's the part that we use as reference to say if a body has stopped or is still moving. After the trunk has come to a stop, the rest is Follow Through Action: head, hair, arms, legs, clothes and accessories, pies included.

If the root bone in a rigged character is part of the body skeleton, it's usually located at the hips or more specifically the pelvis.

The center of mass of the body varies a little with gender, age, shape and pose, but it's close to (higher than) the hips in adults, so they are also important for a body's balance.

[edit] A few more examples

• A classic example in cartoons is the fat character with bouncing belly and cheeks;
• adipose tissue (fat) in general: belly, breasts, cheeks, etc;
• long hair;
• antennae;
• clothing.

[edit] Physics

More...

[edit] Story Development

More...

[edit] Notes

[edit] Freeze!

Characters should not halt completely, even after Follow Through and Overlapping motions settle down. Well, in fact many cartoons do this, specially while another character is talking. But this is a sin for those wanting the "illusion of life", it just kills it. And it's much worse in 3D, with the better lighting, camera motion. To avoid halts, animators can use Moving Holds, make characters breath harder (specially if tired), etc.

Summer of documentation 2006 -- Willian 07:20, 5 July 2006 (CEST)