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36 - Rotoscoping & faking depth of field - Track Matts


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Hey, in this video we're going to look at something called Rotoscoping, using the Roto Brush. Now essentially, all that it is, is masking, but in the previous exercises we used kind of standard shapes. In this one we're going to do some custom easing. So what I would like to do is actually cut myself out, and fake a bit of dip of the field. Dip of the field is kind of-- this background's all fuzzy, and the camera isn't very sharp, either fuzzy, and out of focus in the background. So we're faking this, because what I've done is this. If I have a look, I've got a top layer, which is sharp. The one in there, it's been made blurry. So I cut the top layer out, and watch this, if I turn the bottom layer out, there's me, so I cut out the top layer, and the one at the bottom. If I turn the top layer off, can you see, the bottom layer is all blurry.

I've just got this color of the top that’s in nice sharp focus. That's what we're going to do now using the Roto Brush. First, let's import our bit of footage, we're going to use 'Rotoscoping1.mp4'. Let's make a new 'Comp' from it. Great. Before we move on - this footage is just shot from my DSLR camera - we're going to clean that up a little bit first of all before we do the—

We're going to use 'Lumetri', which we've used before. I'm going to drag it on, and just make it look a little prettier. So I'm going to use basic corrections, probably the big one is temperature, it's a bit blue. I'm going to warm it up a little bit, and then just play around with these. Remember, start at the top, just work backwards, forwards. Am I making it better, am I making it worse? Remember, there's no right or wrong. You're just working your way through these settings.

The last thing I definitely want to do is-- and the basic corrections, one of them is 'Saturation', I'm going to lift this up a little bit just to make it a little warmer. It's probably a little warm. A little more saturated. There we go, cool. You see this 'fx' button here? I can turn this on and off. Have I made it better? Have I made it worse? Yes, it's a little bit over saturated, but I like it. It looks like a nice warm day, and a happy man, doing happy things.

So I've got Lumetri done. Let's right click this guy, and rename it. Let's call this one 'Sharp'. So I'm going to keep this one sharp, and cut out the background. So, to cut out the background we're going to use something called a Roto Brush. Now we're going to have our play head right at the beginning here. And we're going to grab our Roto Brush tool. And we're going to-- this is important, you double click the video here. We go inside, there was the original one, we go inside this guy here, and we're going to do Roto Brushing in here, and when we're finished, we come back out to our composition, so inside the layer.

The way it works is, I click, hold, and paint over the things I want to keep. So if I click, hold, and paint it on my face, watch what happens. Kind of spreads out. Can you see that purple line that sprays over everything? Let me zoom in a little bit. Can you see this purple line? That's the mask that you're making. So what you got to do-- It gets better and better as it moves along. I'm going to drag this down a little bit. I'm not holding anything down on my keyboard, just painting across. I'm trying to get what's little left of my hair. I grab my ear. You can see, it starts getting other bits. It starts getting clever and clever as it goes along. Just make sure you don't miss any bits. You might have to go around and keep looking out for the purple. Can you see here, I've got too close to the edge, this total new range between the back of the wall and my skin is actually similar.

So what we're going to have to do is minus this bit out. At the moment it's green, so it's adding to it. So if we hold down the 'Option' key on a Mac, or 'Alt' key on a PC, can you see, it changes to this, and now I click, hold, and paint up this part. You're going to spend your time going around painting bits in. It's going to grab lots of things you do want, and then it's going to grow, can you see, it reached out and grabbed this keyboard that I don't want. So I'm going to hold down 'Alt' or 'Option' on a Mac. I'm going to paint these things out. Great! It's good in there, doing okay. A bit hard down there. Now, Roto Brushing… Roto Brushing is amazingly quick compared to its predecessor using the pen tool to do it.

So the Roto Brush is good, but it does take a long time. If you're using this particular exercise, this bit's probably going to catch you out. See these white bits of words, it's really hard to see the purple around the outside. So I'm just going to paint in, make sure I grab all of these guys, and make sure—

The way you know you've got them all is, if I undo that, if I jump back here, you'll see these holes left in it. So if I jump back here, paint these out, I'll leave the 'E' there, you can see, the E's gone. You just got to make sure-- paint on you, you, and you. Now if I jump back, it's looking better. I need my arm. I need more of my arm, more of my arm. And this, the chair, so holding down 'Option'. And because I'm masking this just to blur the background, we don't have to be too good. And in fact, if I was shooting it, which I was, shooting it, and I was tending this through Rotoscoping, I just found this, this kind of stuff to use. It wasn't shot specifically for this. I would make sure I wasn't using a black shirt against a black chair because it obviously causes lots of trouble trying to match these two.

It's done all right here, Roto Brush is pretty clever but it can cause problems. So we've masked part of it but we've masked just one frame. You can see this kind of edge here. You can use things like the 'Feather'. I might crank up the 'Feather' just a little bit, just to blur it. Crank it a little bit more just to kind of fuzzy this edge. I could spend more time going through with the Roto Brush tool but I'm just going to fade it so it's less obvious. I'm going to go back in here. Now, we've done it for the first frame. Now what you could, or might have to do is do every single frame. We've got 15 seconds here, 25 frames/sec. If you do the math, I can't. You'll be there for a long time.

Now, what Roto Brush is good at, is trying to guess. So what you do is, you jump along a little bit. Maybe just-- I'm going to drag along the time line, and watch what happens. It's chewing away, and what we're looking for is-- it's a little hard to see, I guess. There's this little line that joins up. And it's trying to calculate between where we were, and where we are now. And trying to get-- it's done a pretty good job, let's have a look. It's done a pretty good job. You might have to touch in a few things, like that. Yes, it's done a pretty good job there.

So what I'm going to do is, two things. One is, can you see here, this is the line, this is where you go to Roto Brush tool. At the moment it's going to here, and then it will finish. What I want to do is-- I still want Roto Brush to go through this whole long list here, so there's this weird little-- what you call it, Chevron thing down the bottom here. Drag it, so you're going to do the whole thing, the whole 15 seconds. And what we're going to do is we're going to come along and how long? Watch this, we're going to jump out to this part, watch this little line. Zoom in a bit, here he is. Just come along, and he's done a pretty good job. If I drag it out really far it's going to go off, and try and calculate. Watch this line. It's going to calculate everything in between. This is probably too far. It's only at a couple of seconds and hoping that it guesses it. It's really easy actually if you've got something of a really high contrast, I know that this is not. It's going to blend it with the chair probably, and the keyboard. Maybe it will, maybe it won't. Let's see how it goes.

See that little line, here it goes. Where are we now? It's done a pretty good job, it's lost my ear. And you can see over here, I have to minus this bit of chair off. So it's not bad. All you'll have to do is keep working your way through this in smaller steps. I've done quite a big chunk in this case. So, work along in middle steps until you get to the end of your footage. Now, in my case, I'm going to leave it till about there. I could drag my play head out all the way to the end here and hopefully it fills in the gaps, it won't, it's not still that clever, especially with this black on black, and the black of the keyboard back there.

What will happen is, as you work your way through a couple of frames at a time, drag along a little bit you might have to work backwards. Once you're finished, you're going to have this one called 'Freeze'. Now what 'Freeze' will do, at the moment, it's trying to render it every time you drag the play head. Freezing this would say, process it all, and just wait. And stop trying to redraw this every time I went to play head. So you hit 'Freeze', kick back, relax and it will take a very long time. So we're going to speed this up at supersonic speeds to get to the end. And it's going to try and do the whole thing for me.

Now, because I didn't spend as much time going through with the brush tool adding and subtracting, it's going to lose this little way along the time. Let’s speed this up, and we'll see what it looks like when we're finished. All right, that's locked it into position. And you could see here, that is me, cut out. So, what I'm going to do is-- I'm going to lift this up a little bit. And I'm going to twirl that one up, I've got my sharp version. I'm going to copy and paste this one, so I've selected it here, and I'm going to go to 'Edit', 'Copy', 'Edit', 'Paste'. I'm going to right click this one, call this one 'Blurry'. I'm going to put this at the back.

At the moment, they're both the same, right? So this bottom one though is-- I'm going to keep the Lumetri color. Where it says 'Roto Brush', I'm going to turn that off. So he's back there. What I'd like to do to him though is-- over here, I'm going to find 'Gaussian Blur' I'm going to drag it on to-- I could drag it to this layer but I'm going to actually just make sure I get on to the right layer. The blurry one. Blurriness… how blurry? I'll crank it right up, it says '10', let's go to '30'. Can you see, the background is really blurry?

For this example I'll keep it quite higher, probably wouldn't keep it this high when I was using it. So, background's nice and blurry, but the top one is nice and sharp. You can see here, if I turn the top one off. There's a sharp Dan, and there's a blurry Dan. Cool.

So that's how to use the Roto Brush to isolate something in moving live footage. Now we've done it to blur the background. It could be that you want to desaturate the background. It might be that you want to cut something, you want to put it t in different scenes. So you're going to use Roto Brush just to cut me out and put me on a different background. Instead of being in my office, I could be on a tropical holiday.

So, let's look in the next exercise as well to look through another kind of used case for using the Roto Brush. All right, I'll see you in the next video.

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