Join Jeff Foster for an in-depth discussion in this video Roto-painting mattes, part of Advanced Compositing, Tracking, and Roto Techniques with After Effects.
So, now that I have my character rotoed out with Roto brush, and I've got that layer frozen. What I like to do next is actually create a movie from this layer, so that I don't have to work on the actual Roto layer. So, I turn off everything except for just this layer. So, I've got this black alpha out here. And I render out a movie and bring that back in as a movie with an alpha. I've already got one rendered out here that I can use. I just drag that down into my project.
And I can hide this guy, a Roto layer, and I can bring in all of my other layers, as I want to make them visible. So, now I've got just a movie, I don't have data that I'm trying to push, and that speeds up my machine quite a bit. Plus it allows me to go in there and modify this movie, or paint on this movie layer, and it doesn't affect any edge data or any masking data. It's not trying to make theINAUDIBLE work too hard. So, the first thing I do is come in here and apply some key light.
I like to get rid of the green screen, so I know what I'm going to be painting on. So, I find an area here where there's a little bit of the green showing. Find a frame here that has enough green to grab and go up 100% and there's probably enough right there. So, I'm going to apply Keylight. So, Key > Keylight. Going to use my Eyedropper and grab that little section of green right there. Does a first pass, so we'll go to our Screen Matte and move up here I want to make sure I try to get as much of the noise as possible. So, I'm going to Screen Matte.
And clip white. I'll bring that down till most of the noise is out of his pants and his arms. There, the sleeve on his jacket. So, that looks pretty good. Then come back to my final result. And what I typically do, is not use this layer as my actual final layer. I use this as a mask layer. So, I'll copy my original layer, duplicate it, Cmd+D or Ctrl+D on the PC. And rename it, and I'll just call it Hero Overlay.
So, what I do here is I put this right up underneath my Matte movie. And I make it visible. And then I come up to Layer > Track Matte > Alpha Matte. And now, of course, I've got some of my green spill still coming back in there. So, I just do a real general Keylight. Effect on there. So, instead of selecting a green color with a Eyedropper. I just go out here and pick a pure green and get close go 0, 255, 0 that's good pure green.
Pick that and I leave it. And that allows me to pull out all of the green out of this image, without affecting any of the subtleties of any noise or anything that's going on in here. And that just gives me a really nice clean look. So, as opposed to the fully keyed version. So, what I'm going to do though is that's just my overlay, I'm going to actually paint on my Roto matte layer. So, I'm going to double-click that, so I can see what's going on here. And bring him down.
And use my Wacom tablet again, to cycle through all of these shots and see where I need to go in and paint out some areas. I'm going to use the Eraser tool. At this point, I don't need thatLAUGH big of a brush. It right now, so I'm going to bring that down. But I'm going to use one that looks like it's probably too big. In some areas, because if you use your brush out around the edges and you have a fat brush, then it's going to come in very subtly.
Because you have to remember, I'm going to punch a hole in his back here to demonstrate. But if you see how wide the brush goes out. And you have all these soft edges all around the edge of the brush. Well, obviously, we don't want a bazooka hole in the middle of him, so we'll undo that. But I do want to be able to come in and just come in very subtly around the top of his head there. Cuz there's going to be motion blur, that I want to make sure retains in there. And I'll go back a frame, forward a frame.
I can see I need to do that again, here. And I just concentrate, when I've got a shot this short. This is less than a second long. It's only 20 frames long. I only concentrate on one part of the subject at a time. So, right now I'm just looking at the top of his head. I probably have other areas I need to work on too, but this way I can work on just one segment at at time. Kind of work my way down, and that way I'm really concentrating on how that edge is going, step by step. Because it's real easy to miss something, if you're jumping all around, or overpaint something, so you actually introduce more problems than you're fixing.
So, it's really important, to, really focus on going back and forth, back and forth, and making sure you're not creating more problems than you're fixing here. So, you know, sometimes it's just a matter of softening it up again here. Now, we use the Roto brush and we had a 40% feather on there. That's the maximum. And it only goes so far, especially with the motion blurry taking over that actually creates some more hair. So, there's points in here where you want to soften up an edge that might be a little bit too harsh and may make the composite not look as believable.
So, you want to kind of knock those back a bit. And this is just a great way to be able to do that is using the Eraser tool with the Wacom tablet to go frame by frame. So, I'll just continue to do this until I get all the way through. My whole shot sequence and play with this and we'll come back and we'll take it to the next level.
- Roto-painting techniques with a Wacom tablet
- Keying both green and blue in a composite
- Masking to isolate parts of an object to key
- Using multiple layers and roto on a bad green-screen shot
- Motion tracking and match-moving
- Matte painting and moving background/foreground plates
- Lighting techniques in post