Join Jeff Foster for an in-depth discussion in this video Simulating lighting to change a scene in post, part of After Effects: Advanced Compositing Tracking and Roto Techniques.
On this project I want to show how easy it is to totally change, the feeling, the emotion. And the setting of a scene just by making some variations in our levels and replacing our background. Now in this case we start with a project that we did in chapter three for the match moving. And it's the Christmas window project. And in this case we had warmed up all of the foreground lighting, the frame around the window. And everything to kind of match this warm homey feeling here.
But what we're going to do is actually change it. To a different part of the world. And we're in a big city now. So we're looking out the window of a high rise building. And the lighting coming back in is much cooler. It's a winter scene, so, it's going to have this reflective light. It's going to be very blue, which is going to make everything look kind of blue and kind of pinkish. Instead of this nice warm glow. So in this case, we change not only the background. But we also change some of the lighting. And there are a few different steps we need to take to do this. So we can open up that Chapter 3 project.
The Christmas Windows Track project. And I have already created one comp that's already done for you. It's the Christmas Window Lighting city. And that's already done. We'll refer to that to kind of speed things up here. But we're going to start with the one that was completed from that chapter. And that's the Christmas Window Home completed. And this has everything and it has all our levels for this. Masks are all created for the snow and everything. So we're going to modify this one. And create an entirely different scene.
So the first thing that I'm going to do is get a new background in. And this I stock photo image, here, is going to be our background that we'll use. And it's this city scene. And I just hide the original one, which was with the snowman in the yard. And we can see while the colors are way off here and everything. We're going to have to do a few things to make this work. Well, first thing I wannna do is so I don't have to go through all the steps of retracking anything. Is, I'm going to just copy all of my key frames from the original.
So, I just select and drag over here. And hit Cmd+C or Ctrl+C on the PC. And then I close that up, twirl this down here. Come down to Transform, make sure that I'm at frame 0 and I just paste. And it will automatically change all my anchor point position. And scale and have all that tracking information, in there right on that layer. So, I'm set to go there. So, let's close this back up.
We don't have to do anything more to that layer, 'cuz we're going to keep that cool color in there. That's actually going to be what we use to transform our foreground so that it matches a little better. Another thing I'm going to do is, I'm going to, get rid of this Mask layer here. Because we no longer have artificial light that's lighting up the snow. So we don't need that. Actually, I can just hit Delete. And that way our snow is on it's own layer here.
And will come back up here to Track matte to No Track matte. And that's set. I'll need to change my color on that snow, so I'm going to click on Hue saturation here, and just delete that. Because I want it to be a little wider. I want it to be a little cooler in color temperature. So now I've got my background and, I've got my snow has already set there. But one thing I want to do, is actually add more snow. Because we're looking at a wider range here and deeper.
So I'm going to go at about 4000 here and I may change the speed up a bit, go to like 0.75. And that will give us more snow and a little higher drop rate. And that way it will look a little more believable, be it a little more dense as we're looking out the window. 'Cuz we're not just looking in a short little shallow area in a yard. We're actually looking out a window of a skyscraper here. So, that sets up our background. We're all set there. Now, what we have to do is bring our foreground, into play here. So, we're going to be changing our colors here quite a bit. So, I'm going to my levels on this layer and I'm just going to click Reset. Which takes a second to reset, there we go.
And I'm going to start at this point and actually bring everything down just a bit. Because it's going to be a little darker in here. And then I want to cool it off, so I'm going to come down here to my blues. And I'm going to to make everything go a little bit more toward blue. So we're actually getting a little bit of this pink, in here. And then, I'm going to actually, bring the reds down just a little bit.
But don't want it to go too red. There we go again, make it a little less saturated that way. There we go. And may bring the whites down just a bit so they're not quite so intense. So I'm going to bring my output light down just a little. So this is kind of a subjective theme, you can play with a bit. The blues, I think I might back off just a little bit, I went a little too far with the blues. But you can play around with that, you can go back and forth. And look and see the one that we already did, to the one that you're working on. I'm still having a problem here with this being to light over here. I wannna darken that up, bring more of the focus around the tree here. And the way that I did that was to just duplicate this layer. Just Cmd+D, on the keyboard, or Ctrl+D on the PC. And I've, don't really need to mess with this right now. I'm going to create a new mask here.
So let me bring this down to a little smaller where I can see what I'm working on. I'm going to create just a really crude mask here. Around this part of the image area, let's close it up. Then I'll come over here and Mask shape, and Feather. Feather's what I want here. Then we'll come up to Mask feather.
And I'm going to go about 250 pixels. Because I want a nice big soft feathered area here. And then I'll just drag this over a bit. And notice I started on frame 0. Very important that I start there, because I'm going to have to move this a bit as I go down in time. And we can hide the layer underneath. So we can see about how much we're affecting. And I'm going to come in here to my levels on this layer and I'm going to make it a bit darker. So, let's go to our RGB Channels and then we'll make that go considerably darker. So that our focus really is on this tree and the light that's coming from here. So, go too dark but that's, that's better.
Now what's going to happen is as the camera passes by. It's actually going to change where the focus is so this has to track, that. And we're just going to do just a real simple Mask match move with it. So let's go back to frame 0, open up my mask. And click on the Stopwatch for Mask path, which sets it there. Then I'll come out here a little ways, right around three seconds, and then move this guy over just a little bit. And I may start to bring these down.
Because we're going to get closer here. So I come back out to my last frame. And wait for it to redraw. There we go. That's all set. So let's grab all of them and we'll move them up, and over. And then bring these two down. So, what we're basically doing is trying to just mask out what area is going to be dark. And what area is going to stay light. So now we can see that back. Let's look at the one that's already finished here for a comparison.
I went a little darker with that one. But you can see here that the mask has moved slightly over time. To kind of follow that main direction where the light's coming from. Looks something like this. And now we've got an entirely different scene built from something that we already based it on. And this is important to know how to do this. And do it pretty quickly because you're going to get clients that say, you know, I really like that, but we need to change it up.
We need to change it this year, and you're using something you created last year. And they want to change, you know, a setting or something, or they want to see variations of something. We want to see what this would look like for this, this, this, and this. And that way your not having to re-invent the wheel all the time. But you are able to basically do the job once and then, make modifications to that time and time again. That just gives you a lot more control and a lot more variations that you can present. Or just to be creative for your own purposes.
That's just another way to be creative, using the same project. And just applying some assimilated lighting changes to it.
- 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