Original subtitles

- [Instructor] Before we start creating

our run cycle animation.

We need to study a bit some references.

You can easily find some breakdowns

of run cycle animation online

but it's always a good thing to study some references

to train your eyes,

to learn what to look for and to avoid mistakes.

While I will make a slightly stylized run cycle,

the physicality and principle

of a realistic run cycles still apply.

Only the rhythm and the amplitude or the exaggeration

will make the difference.

You will find the link to different reference videos,

I've picked on YouTube in the documentation.

I will use since sketch to currently study

the ones I'm showing you right now.

When working on the run cycle,

we will mainly focus on for poses.

So down or passing pose, the push,

the up pose and finally, the straight leg just before

the contact and the end of the cycle.

when working on the cycle analogies,

I advise you to focus on one feature at a time.

The first thing I will check here

is the shape of the spine and the overall line of action

between the contact pose and the down pose,

we can see how the whole characters spine

and line of action from the foot form some kind of S shape.

So from the front view,

if we isolate the spine from the hips and the shoulder,

it creates a C shape.

And from the side view,

it does create a C shape for what too,

during the down pose or passing pose,

the shape is almost the same,

but it's getting slightly straighter.

I think the pushing pose is one of the most iconic pose

during a run because the line of action

is super easy to read,

creating both from the side view and the front view,

a nice elongated arc.

During the up pose,

our character's spine from the front view

is almost straight

and from the side view while the character

is slightly leaning forward,

the spine is also looking a bit straight.

This is the time where we will be mirroring the cycle

in a way and shifting the shape of the torso

onto the other side.

One of the most important thing to get right when animating

a character is the relation between the shoulders

and the hips.

The thing you must keep in mind,

whenever you are posing the torso of your character

is counter posing or contra posto.

The human spine is a bull of a very little compression sense

to the discs we have between our bones.

And when aging those discs get a little stiffer

and a little smaller,

this is why when getting old you often lose

like one centimeter.

In this case,

you don't really need to think about the relationship

between your shoulder position and the hips.

But when you are leaning on a side,

you will generally compensate this rotation

by pushing onto your leg to support the weight

that has shifted.

As you trying to keep balance,

your hips will be raising upon the tool

of the lean shoulder.

So when you're posing your character,

always think of a V-shape formed by the plane

of the shoulders and the plane of the hips.

From the side view,

we will have exactly the same behavior.

If you lean forward to pick something

on the ground for example,

your hips will naturally rotate the opposite way

so that you keep balance.

Just make a test,

try bending forward and rotate your hips backwards,

you will have a very hard time keeping balance

and you will tend to move your whole body back

so that your feet are aligned with your neck.

So the relation between your shoulders,

your hips and your feet is always about keeping balance.

And counter posing also helps here during a twist.

If you twist your upper body right,

there are big chances that you will slightly compensate

with your hips.

So if we now get back to our references,

it will be kind of obvious.

When the left side of the hips of Usain Bolt

are twisted forward

his right shoulder is twisting forward to compensate.

And you can observe exactly the same thing

on the front view.

If we get a little further in the video,

we can clearly see this twisting

with the left shoulder forward while

the hips are twisting the opposite way.

If we have a look at some of the key poses

of our characters,

we will easily find our V-shapes during

the passing or down pose

all the weight is on one foot,

pushing the hips upward.

If you have a hard time distinguishing the hips

you can use the silhouette of the character.

So we can see the hips raising from left to right

and the shoulder leaning down from left to right.

During the up pose where both feet

are no longer on the ground,

we generally have almost a straight hips

and straight shoulders.

Some kind of parallel hips and shoulders,

since the body is no longer supporting any weight,

but prepare to transition into bending the other way.

But as we transitioned to the contact pose,

we can see the hips and shoulder counter posing again

into a V-shape.

And from there,

we'll be transitioning into a new passing pose

where the leg is pushing the hips upward

and the shoulders are compensating.

In the run cycle,

one of the most important thing is up and down

of the center of gravity.

But the most common mistake I see on beginners run cycle

are the left to right motion.

The first very important thing to think about

is that the faster you run, the less left to right motion

you will have.

And this is why run cycles are easier than walk cycle

is that you don't have to think that much about

the weight shifting from left to right,

but there is still a bit of it.

The side to side motion will reach its extreme

a bit after the contact pose.

When the athlete is pushing on his leg to jump,

his leg is pushing on the opposite direction.

So when pushing on the right leg,

his body is translating to the left

and it will take a couple of frame after the contact pose

for the body to absorb this translation

and then go back into a pushing pose

that will push the body the opposite way.

And it's gonna be a bit of the same regarding

the up and down.

While it's pretty easy to spot the up pose

when the character is air bound

the down pose doesn't occur whenever the character

is contacting with the ground but a few frame after,

because again that the body needs some time to compensate

the weight and the momentum.

The relationship between the hands and the legs

is not that complicated.

As for the hips and the shoulder,

they behave the opposite way,

when the right leg is moving forward,

the left hand is moving forward.

When the right hand is back,

the left foot is back

and we will find the same kind of behavior

during a walk cycle.

But there is a subtle but very important difference.

In the run cycle hands are not reacting to the motion,

but they are leading the motion.

If we track the left hand of Usain Bolt

we can see that it reaches its extreme forward pose

or upward pose before the right foot.

And as the foot reaches its extreme forward pose,

the left fist has already started swinging backward.

So during the forward motion,

the fist arrives first and pulls the body up and forward.

And then it swings backward

so that the left hand can arrive first

compared that to the left hand.

And when we hit the passing pose,

we can see that the left hand is already a bit backward

compared to the right foot.

And this is why sprint athletes tend

to have a very muscular upper body.

It allows them to generate a lot of momentum

and energy using their arms to pull their whole body.

Again here,

we can see the left fist moving forward

while the right leg is still dragging back

and now the leg is catching up.

So you need to remember that to get a believable run cycle,

whether it's stylized or not.

Arms are leading the motion,

shoulder and hands are leading the motion.

To wrap up this video,

we will have a quick look to the arc made by the legs.

Here, I've traced the left leg motion,

which using a sprint athlete as a reference

can be a little misleading depending

on what kind of front cycle you want to do.

If you're an average person like me,

there is very little chance that when you run,

you hit this kind of pose.

So never forget that when you are studying references,

put them in their context.

What are you looking at?

So in the context of the more classic run cycle,

even if it is a bit athletic,

your motion path will mostly looks like that.

We can also see that those athletes

are very light on their feet,

mostly running on the tip of their feet

while we may furtherize a rolling foot

from the heel to the tip when we will do our own cycle.

It will be also important to study the shape of the arm.

Look at when it reaches the back,

it's mostly angled and then it gets straight

during the passing pose.

And then it gets very angled when reaching its higher pose.

We've the elbow leading the motion,

meaning that the elbow will reach its extreme pose

a little before the hand, maybe one frame.

Since we will be using forward kinematics

to animate the arms,

we don't really need to track the arc on the reference.

You can do it,

but I believe that the pose is more important.

A final thought is the position of the foot

when landing on the ground.

You can see on the right reference that

the foot will be slightly shifting to the inside

when hitting the ground.

These are little details that can make your run cycle

way more believable or interesting.

Also you should avoid to make a straight line

with the foot motion.

You should make a slight left to right arch

during the passing pose,

where the foot we get to the side during the passing

and get a little centered during the contact frame.

We could analyze those reference forever.

So what we will do is that we will jump

into the blocking of our run cycle

and for each pose,

we will try to think about all those details.