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RoboTV: Keyframe interpolation

From: After Effects Apprentice 07: Parenting

Video: RoboTV: Keyframe interpolation

In this Idea Corner I want to go through the process of refining and improving this RoboTV animation. Now keep in mind there is no one right solution. However, the general principles remain the same. The first thing I'm going to do is preview this a few times and just see what I like and what I don't like about the current animation. I press to 0 on the numeric keypad for RAM Preview. (Whir, whir, whir) A few things stand out to me.

RoboTV: Keyframe interpolation

In this Idea Corner I want to go through the process of refining and improving this RoboTV animation. Now keep in mind there is no one right solution. However, the general principles remain the same. The first thing I'm going to do is preview this a few times and just see what I like and what I don't like about the current animation. I press to 0 on the numeric keypad for RAM Preview. (Whir, whir, whir) A few things stand out to me.

One is that I'm not entirely happy the arm's movements. For one it's a lot slower through here and at the end than it is in-between, hitting the individual bullet points. So I'm going to do something about that. Two is at this type just sits there. It feels to me like it should be animating on and perhaps even doing something special like hitting every time to the arm comes to one piece of type. Third, I'm missing the background. I need to put something behind here. Hopefully, something that ties in a bit with some of the things I see inside the video.

You see a lot of squares, a plywood, and lands. That gives me an idea. Finally, I want to make sure that everything is nice and readable. For example, this text is not entirely readable over this robot arm. So I might want to improve that as well. So let's go tackle these. My first problem is the arm's movement. I have a longer period of time at the start and end phase than I do in-between words. There is a couple of ways I can speed up the arm's movement in there. One is I might grab this last set of the keyframes and just move them earlier in time.

For example, maybe to punctuate that particular base note. So I am going to select these keyframes, start dragging, add the Shift key, and now they will snap to that particular beat. Now that duration looks roughly the same as this duration. I'll RAM preview again. (Whir, whir, whir) Yeah, I do like that timing better. Next, I would like to make the movement of this arm more realistic. My first job out of college was actually programming assembly line robots and I know that these big heavy arms do not start and stop instantaneously.

They have a lot of mass to them so they come into there final resting place slowly to make sure they hit there mark and there is a little bit inertia as they leave a spot as well. However, as you see down here in the Timeline panel, the default keyframe type in After Effects is all linear, which means sudden starts and stops. So let's refine that. To do this we should head into the Graph Editor. We cover this back in the After Effects Apprentice Advance Animation lesson. I'll go ahead and click Rotation for the Small Arm, then Shift-click on Rotation for Medium and Big Arm to get them all up at the same time.

And you can see that these straight lines indicate constant speed in-between the keyframes. Well, let's change that. I'm going to start by selecting all of those keyframes by dragging a marquee around them and I'll start with the instant gratification trick of using Easy Ease keyframes. There is actually a button for it down here at the bottom of the Graph Editor. As soon as I click on this, you'll see that all of these curves have changed and indeed we're now slowly coming out of this value changes. That's what the flatness at the top indicates.

Changing value more quickly in the middle and slowly coming into the next value. I can talk about it or I can preview it so you can see it. (Whir, whir, whir) Just that little bit of easing I think has helped quite a bit. But I'm going to push this one step further. As I mentioned earlier, the robot arms need to come into their stop position more slowly to make sure they don't miss the spot. So they don't jiggle back and forth.

However, they're able to leave a spot very quickly. They don't care about precision at that point. So to better mimic that I want to click off to lose my current selection and drag marquees just around the keyframes that exit those held positions at each word, hold down the Shift key, select those keyframes, hold down Shift, select those, and select those as well. Now that I have all of those exit keyframes selected, I could either drag the influence handle for one of them and this will shorten the influence for all my selected keyframes.

If I do have a problem, I drag up or down. I can hold the Shift key to make it come straight in and out of the keyframes. O r again I could just take advantage of these buttons at the bottom of the Graph Editor. For example, for Auto Bezier which does give a little bit of rounding to my velocity. I'll click on that and you'll see how the curves have changed slightly. They still come into keyframes slowly, but now they exit keyframes more quickly. You'll see something very similar if I choose linear keyframes as well. The handles go away, the curves are very similar, but I am going to stick with Auto Bezier just to get that little bit of extra rounding come out of these keyframes.

Let's RAM preview again. (Whir, whir, whir) Well, now I have got a problem. I have got this very awkward overshoot as I try to land on each word. Again, if you look closely at what's going on the Graph Editor, you'll see exactly what the problem is. There is a little keyframes influence handle coming into each of these keyframes and that is what's causing this overshoot behavior. You'll see we are 341 degrees here, but as we move along here we're overshooting to almost 346 degrees before landing back at 341.

What we want this robot to do is to hold its position during those seven or eight frames and indeed that's the answer. Hold keyframes. So I'm going to marquee around all of the entrance keyframes when we're landing on a new word. Again, I am holding down the Shift key to add to my selection and I'll click on the button at the bottom of a Graph Editor for hold keyframes. Watch what happens to the curve as soon as I click this button. You'll notice that these lines have flattened out. There is still an influence handle coming into that keyframe, but it's being ignored by the hold behavior coming out of a prior keyframes and indeed we're holding 341 degrees for the entire seven or eight frames.

RAM preview one more time. (Whir, whir, whir) That's exactly the behavior we want, just a little bit of velocity change coming into and leaving keyframes, no wandering, while we are supposed to be holding on each one of those words. I click on the Graph Editor Button to go back to the normal view and here are all our edited keyframes.

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This video is part of

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After Effects Apprentice 07: Parenting

17 video lessons · 7222 viewers

Chris Meyer and Trish Meyer
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