Learn about motion tracking the PixelChooser selection by using the integrated interface with Mocha and get a brief introduction to tracking a mask in Mocha.
- [Instructor] Use the PixelChooser function built into the Boris effect to limit where the effect is appearing on the layer. In this case, the mosaic effect is kept to this circular area over the joggers face. Now, if I move forward on the timeline there's going to be a problem though. The effect slips off. It doesn't follow her as she moves forward. So what we do? Well, we need to animate that mask somehow, or motion track it somehow, or use some combination of those two things. Well luckily, Boris effects have a built-in link to mocha for just that purpose.
Let's give it a try. I go back to the first frame, select my layer, go to the effect controls panel, and right there is a giant mocha button. If I click that button, it opens mocha. And this is a version that comes bundled with after effects. And mocha is a advanced planar tracking tool that you can use to export motion tracking data, or export a motion-tracked shape, like for a mask. Now it's a pretty deep program.
There are a lot of properties and techniques associated with it, so I'm just going to limit the discussion to what you need to do to make this work with PixelChooser. All right, I'm going to take a look of the footage before I actually track it. I can use the time slider and just take a look. I know that one thing that might throw a tracker off is the fact that her face goes in and out of shadow. So maybe our track initially won't be perfect, but there are some quick ways you can adjust that to make it work for this particular project.
All right, so I'm going to zoom in here closer to her face so I can see what's going on. Grab the zoom tool, and left mouse button drag up to get closer. You can also middle mouse button scroll. There we go. Now I need to draw a shape that represents where that mask is going to be. There's a couple ways to do that inside mocha. One is to use the bezier tool, and the other is a x-spline. I like using the x-spline, so I'm going to use that. I'll click that, and then I'm going to define that mask shape by clicking to create control points.
So maybe above her face, one behind her ear, one below the chin, and one in front. Now to finish this shape, I need to right mouse button click, and that will make it permanent. There we go. Initially this shape is very square, but you can adjust these blue handles, click-drag those points, to make that more circular. And what I want is a roughly circular or oval shape around her face to determine where that mosaic will be.
It doesn't have to be a perfect circle though. It's a bit small right now, so I'm going to click-drag my original points outwards to make that larger. Something like this, so it's in front of her profile, below her chin, behind her ear, and above her hairline. Something like that. Once I have the shape, then I can actually tack it. And mocha has tracking buttons right here, the ones with the small Ts. For example, I can track forward.
When I do that, it plays forward and attempts to keep that pattern within the circle in the same place at all times, therefore the circle updates in terms its position and shape. It's not perfect. Again, the lighting is probably throwing this off a bit. You see how by the end the circle's a bit distorted. But, as a quick fix, I can set some additional key frames. Now there are many ways to refine tracking inside mocha. That gets into a very long conversation, but, just for this project, I'm going to quickly change the shape like this.
And that forces a new key frame on the timeline. Mocha looks at that and tries to update the entire timeline based on whatever key frames you have. It won't be perfect, but it'll be closer. Now I can grab the time slider and then scroll through and see how it looks over all. A bit better. But it gets a little funny somewhere towards the center here where she has too much room in front of her face.
Now some shape change should be expected because she's moving her head back and forth. All right, so there are essentially three key frames, and it follows pretty well. Okay, and once I'm satisfied with that shape, then I can return it to after effects. And the way to do that is to save it. I go to file, you'll see there's no save project as. We'll the save the project, and that will pass the data back to the Boris effect.
So save project, and then exit mocha. I'll just use the close X at the top. Instantaneously, it passes the data back. In fact, the shape updates. If I look back at the PixelChooser mocha rollout or section, you'll see that it's changed the shape menu to shape mocha spline. Now when I play it back, it's going to follow her face. Again, it wasn't a perfect circle, but, considering we have a feather on this and it's pixelated, it's close enough.
And there we go. And now we have no idea who she is. So if you want a Boris effect to follow something, you can use the mocha button and do some quick tracking to get that spline shape back into after effects.
VFX expert Lee Lanier begins by exploring shared Boris Continuum controls, and then shows how to apply stylistic effects. He explains how to work with the PixelChooser and Boris Lights, and discusses how to color grade and warp footage. He also takes you through using the Boris Chroma Key Studio and working with Mocha Pro for motion tracking, as well as how to add particles and work with 3D text.
- Overview of Boris Continuum
- After Effects preferences
- Applying stylistic effects
- Relighting with Boris Lights
- Adjusting colors
- Changing the time of day
- Warping footage
- Keying green screen
- Motion tracking
- Adding particles
- Working with 3D text