Introduction to the Graph Editor

- [Instructor] Animation is represented in after effects in a few different ways. We've seen animation taking place in the composition window where our layers move around the screen, and we've seen animation expressed as key frames in the timeline via the default layer bar mode, where layers appear as color bars that are stacked on top of each other. After effects has another method to visualize our animation in what's known as the graph editor. And so to get to the graph editor, let's click on this button right here, and you'll notice there's nothing in here, and that's because we have to have a layer selected with a property that has key framed animation.

So, let's select our position key frames here, and this is just our linear baserunner guy that runs across. And it's important to note that the graph editor is a place where the interpolation of key frames can be viewed as either a speed change, how fast an animation is taking place, or as a change in value for a given parameter. So really, it has two functions. This graph editor in this view is known as the speed graph. So, let's take a look at that. It's just like horizontal lines here, and it's drastically different than the value graph.

And the value graph here, in this case, is showing the X and Y position of our layer, and if we hover over it, let's see what's happening here. Our X position over time is changing, and when we land on key frames, these are the points in time where we have these nods. And so, this really just correlates to the value of a given position, so if we had scale, these values would change out to 150%, this is now linear because there is no change in value, but it shows now that the value is 150%, our rotation is set to 90.

If we move this around, we see that these values are changing. So really, all this reflects is the value that we have in this area here. It's important to note too, that any given time, we can follow along and see and pinpoint where in space this lives. So, for X, we have 773 pixels, and that just correlates to the X position in the composition window. Let's go over here to view, and enable Show Rulers, and I'm going to click and drag a guide, and you'll see here in this position guide, position lives roughly at 767.

That's 767 pixels out from the origin, and the origin is zero zero, is right here, at the top left. And you'll see here in this value for the info that to be true, so roughly zero zero. And if we go down to the bottom right, we see that it's roughly 1280 by 720, and for this particular guide, we are kind of in the vicinity of 770, and that correlates to this value here, which correlates to this value here.

So that all makes sense, any given point in time you can kind of find out the value of a given parameter. I'm going to turn off the show rulers, and let's clear that guide. Let's hop over to the speed graph and see what's going on there. We have a horizontal line all the way across, and if we hover over that line, we see that 788 pixels per second is the value that we're getting, what does that mean actually? Well, it means that between these key frames, this particular layer is moving in a position that is 788 pixels fast.

So, we have a velocity here, but nothing's changing. It's all the same throughout, and so no change inside the speed graph is represented by a horizontal line. That's important to know. So let's switch over to something that does have a little bit of variation, and in this easy ease layer two position key frames, we'll see that we have something drastically different. We have these arcs that go up and down, and for a speed graph, this is really handy to know, it's just that overall, we can see where the fastest point of our animation is taking place, and that just happens to be up at the peak here.

We're moving at roughly 1180, so it's like really fast up here, and then we slow down, all the way down to zero, and speed up again. And so you can see these gradual speed ups and speed downs as we cruise through the timeline here. Let's go ahead and play that in real time. And so now you see our box there is moving from base to base in such a way that as it approaches the base, it slows down, as it leaves the base, it slows down, and it gets its fastest point right in between the two bases.

Let's go ahead and take a look at another example. Let's go ahead and hit animation, reveal properties, and select our position, and we're seeing something radically different here. This is kind of see these high peaks and then real, real abrupt changes in speed. So, when we're on the base, we're basically at zero pixels, but the very next frame, frame 16, we're speeding out of there really fast, an explosion of speed that goes, really tapered off and slows down into the next base.

And it happens again from base to base, so let's go ahead and hit zero on the numeric keypad to see that in motion. Okay, let's take a look at another example, the opposite of that. I'm going to select my position here. So instead now, we're having a gradual ease into speed, and we speed up really, really fast towards the end into the next base. I've kind of taken the liberty to move out the position key frames here so that we are having a slightly different move, we're not following the lines of the bases anymore, but it just goes to show that the speed at which these guys move has a really drastic change in the personality of the movement.

All right, the hold key frames here in layer five, let's go ahead and twirl that down, we have our hold key frame on frame 15, where the runner's at first base. So there's no change here whatsoever in speed. It's down here at zero zero. Likewise, there's no change in speed up here. This is all constant 784 pixels per second all the way up here, but we have movement, because it's speeding through, and all of a sudden we come to an abrupt stop, and then we speed out again.

And so the speed graph here is a really handy way to see where our fastest motion is, where there is no motion at all, and the changes in between. Knowing that there are multiple ways to see animation expressed in After Effects allows us to choose the most appropriate view for any given situation. I highly encourage you to take a look through this scene file and deconstruct what's happening with each view as you make changes to the animation. In the end, having knowledge of how and why this graph editor works the way it does will go a long way to help you manipulate your key frames with greater precision.