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41 - Track motion in After Effects to follow a person like stranger than fiction


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Hey there, in this video we're going to do some Tracking Motion. And I'm going to track part of my glasses here, and get some Text to attach to it. You can see, little dots, likely, we don't have to do them manually. So what happens when I preview it, let's go to full screen. Look at us. Hey, it attaches to my face and moves around, and it's pretty automatic. All right, let's go and do that now in After Effects.

So first thing we're going to do, is we've got a New Project open. In my 'Project Window', I'm going to double click in here to Import. I'm going to bring this one called 'Track Motion.mp4'. All pictures of me talking. Let's make a Comp from it. Either right click it, and go to 'New Comp' from 'Selection' or you can click and hold, and drag it down to this little Icon here. Makes a New Comp. So here's my Comp down here called Track Motion, there's my mp4 on it. Now I'm going to zoom out, so you can see the whole thing. More pictures of me, exciting. And I've kind of wiggled around while I'm talking this. You have a preview and listen to it, but it's me rambling on. I moved around kind of like an idiot, so that there's something to track, otherwise, if I just keep talking, it's not going to be very exciting.

So let's have our Playhead right at the beginning. The first thing we need to do is open up our Tracker Window. If you can't see it, it's over here. We go to 'Window', and go to 'Tracker'. Open it up, and this Layer down here, select it. And click on the one that says 'Track Motion', not Camera. 'Track Motion'. You get this little target in the center here. Now one thing before we move on, is that we've actually dived. That's our Composition that we were looking at a second ago. It's actually opened up a Layer. We've dived inside of it. Remember, at the beginning we showed you how to double click and you get lost inside of here. We're actually inside of here now, so if you lose this Tracking Point, you're like, "Huh, where did they all go?" Just click on this option over here. This little target here is what we're going to use to Track. So what I'm going to do is, at the moment it's quite small. So I'm going to zoom in, and just make it a bit bigger.

To make it bigger, we got our Selection tool, just kind of going to make that bigger. It's the two squares bigger. I'm going to zoom out again. And if you want to move it you have to click anywhere inside of the Main square, but not on the Line, or the Targeted Center. So just drag it, and it kind of aligns here. You can drag them, it's easy to drag. So I'm going to zoom in, and what we're going to do is pick our Targeting Point. It's really easy on mine because I've got my glasses here, there's like this little square. Cool thing about that square is that it appears the whole way through the video. I don't turn around, or anything, so it's a nice easy Target. If you don't have anything easy like that, maybe the Pupil-- My one's not so good because there's a bit of reflection on my glasses. It doesn't have a very good contrast there. You might use the edge of the mouth or a nostril, something that appears the whole way through.

Remember, I'm just going to drag along until we find this thing to hold that. So we've got two Squares and a Target. What do they mean? This outside square is like a general search area. This, I say, have a look in this area, you can see it moves around. So I'm just kind of giving some boundaries to say "Look inside this kind of area for this guy." If it ends up jumping outside of here, it's going to lose the Track Point. The reason we have this outside square is that it's quite system demanding for After Effects to go through and start tracking Data. So if we have this, like massive, covering up the whole thing it's going to take forever to look inside of this in every frame. So just keep it as small as you can, you might have to trial and error. I can see that kind of-- does it dive out? Nearly.

So I might just move it so it's somewhere across there. So that's my Tracking Area, back to the beginning here. This inside area here is what you put around the unique object. So in my case, I'm going to put it around these glasses here. I'm going to make it a bit bigger. So this lens here is a nice easy thing for After Effects to track. It's got a top, and a bottom, and a middle inside, and some corners. So it's just really easy for After Effects to say "I can follow that." It might be around the whole Eyeball, say you're tracking the Pupil with the Target, and just put it around the Eyeball here. Because I've got glasses on, they make a nice easy thing to Track. If you're checking a car, you might put it around the number plate, but Track a certain letter. Or you're going to have to work it out for your specific need.

Now this Target thing here is the important bit, that's the thing we're going to Target. I want to Track that guy there. So, outside bit, general area, inside bit, the specific thing to make it easy for After Effects to not lose this Target. And this Target should be on something unique as well that appears through the whole Scene. To get it going, make sure your Playhead is at the beginning so we can see everything. And we're going to click this one, there he is there. There's two options, there's 'Analyze forward at 1 Frame', or there's, let it go automatically. So One Frame just does one frame. We'll just have a look at it, because it's interesting. You can see, it's moved along to the next Frame. Don't worry that the dots end up here. As long as they end up smooth, as long as this thing keeps on targeting its little part we just got one Frame of my Video over and over again.

Now if yours keep losing it, there's a problem. It could be that the thing's moving too fast so it gets all streaky and blurry. And you might have to go through and readjust this thing, every single Frame. And that will drive you mad. But be aware that not everything can be Tracked. So, play around with this, go forward a few Frames and just see if it does keep Tracking. If it does, great, we can hit the Automatic one and see how well it does. If it doesn't, what you might do is, decide that's not working, tracking this thing here. You might Track the other side, you might Track my ear, my mouth, try different things. So I'm going to hit this middle 'Play', this 'Analyze Forward'. And we're going to kick back and hopefully it's going to do it automatically for us.

It's going reasonably fast, Frame by Frame. You see it Tracking through there. Oh, it's almost lost the Tracking Point. Oh, it's lost it. It's back. So we're watching that Tracking Point, and you've got to decide-- it went down a little bit but because this thing is a bit more of a generic follower, as long as it's following the motion of my head I'm not worried that it got off the center, and got into the corner. So you've got to decide on how Pixel Perfect you need this thing to be. So what we'll do is zoom this up to the end and see how it goes. If it does lose the Target, you might have to stop and try find another Tracking Point. Let's zoom along now. Has it Tracked? I looked away. I wasn't really following it because it took a while. I'm watching the little dots. I'm just watching this Target here, and you can see, followed it. Even when I went all the way out here, it followed it nicely.

Now if you find yours doesn't, you're using the exact same file as me, couple of things to check. You might have to play around, and maybe expand this outside box. Maybe readjust this middle box, and maybe pick a different Target. It should work though. Also if you get lost, remember, you're back here, and you're like "Oh no, what happened to all the dots, they were there, now they're gone." Is just go back into here, and there they are. So we've got this file, what do we do with this Tracking Data? Weirdly we can't just attach Text to it like we want to, like I want to bring in that Speech Bubble. So what we need to do is, we need to do one little trick for After Effects. So let's go back to the beginning here.

A little trick we need to do. We need to create something called a Null Object. Remember, a Null Object is just an empty layer. Think about it as just a completely blank empty layer. That Null can follow these Tracking Points but that Null doesn't do anything. But what you then can do is you can get your Speech Bubble to track the Null. So it's a bit of a way to make it work. So, you say, 'Layer', I want a 'Null', please. Little empty nothingness. Down here, in your Track Panel, you can say I would like to 'Edit Target'. Yes, I'd like that Target to be that Null, click 'OK'. And the last thing you need to do is click 'Apply'. Would you like to track X and Y? Say, yes please. So now we've come out of that Tracking Layer, we've come back into my Comp, but now my Comp, whereas before, it was completely blank, now it's got this red dot all the way across it. That's my Null following around, look at it go. The Null doesn't do anything if I hit Play. So there's nothing there but now I can bring in anything and get it to Parent to that Null.

So you grab the Type tool, and start typing. What we're going to do is, over here, I'm going to my 'Project Window', I'm going to bring in my 'Speech Bubble.ai'. I just made this in Illustrator, very special, I'm going to drag it in. It's got a nice big long shadow, I don't know why I did that. It's just one of the cast in the background here. And where do I want it to go? It's up to you, just put it somewhere. And what we'll do is, we'll Parent it just so you can skip ahead if you want to. So, this Speech Bubble, I'd like it to follow the Null. Remember, the Null follows those Tracking Points. Cool, huh! It's not bad. So, that's it, you Tracked the Motion then you get a Null to follow that, then you Parent something to that Null.

And what we're going to do is, I'm going to Unparent it, I'm going right at the beginning. Unparent it, because I want the Speech Bubble to pop out as well. So we're getting into some generic animation now. So you can skip here if you like. So what I'd like to do is, at the beginning here I'm going to hit 'S' for Scale. I'm going to get it to come along to maybe this far into it, a second and a half. And I'm going to hit 'Scale', start the stopwatch, set it to '0'. And after just a little bit of time, I'm going to get it to go up to 100. So what I want to do is—

Actually, what I'm going to do is do something different. So I'm going to undo, and show you what I did wrong. So that's great, I want to do this but I don't want it Scaling from the bottom. See that there, the Center of Rotation, or the Anchor Point, I want to adjust that first. So I'm going to grab the Anchor Point tool. Grab it, I'm going to put it at the end, or tip of this, because that's where I want to kind of expanding out of. Now I'm going to hit 'Scale', now I'm going to hit '0'. Come along for just a little bit, then I'm going to pop it up to 100. And it's just going to look a bit cool, coming out of there. Does it look cooler? Yes, it does.

I'm going to add my-- instead of Easing, I'm going to use my Expression. I'm going to paste it in there. That's not what I want, I want this thing, copy it, click it in there, paste it in. Hopefully now, it's going to do a little bouncy thing. Cool. Now it depends on where you have your Playhead. Because if I play it here, and now Parent it, it's going to follow it from this point on. So it's going to be kind of coming out of my Eyeball. Watch, it's kind of weird. So what I'm going to do, before I Parent it is just get my Playhead right back at the beginning. And I'm going to say, "You, Parent to the Null from here." Only that much, stop. So that brings out a really good point.

How much does Motion Tracking work for me every single time? I've given you an example that totally works. Are there times where it's just really hard to do Motion Tracking? Yes, it is. So the only way around that really, is to manually move it every Keyframe. And we kind of did this earlier on. Remember, in here, we said, 'Frame', one frame forward. And then we kind of had to move it one frame forward, move it. And you have to do that. Sometimes it will track for half of that, and then lose it. So you can go back, you have to manually move it around for just parts of your video, potentially. This one worked out really well. So half the time it works, half the time it doesn't. It's a really cool effect, anyway. All right, that's going to be it for this one. Let's look at the next video where we do some Manual Tracking madness.

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