Join Chris Meyer for an in-depth discussion in this video Reversible stabilization with Warp Stabilizer VFX, part of Screen Replacement with After Effects and mocha AE.
The purpose of this course was to show you how to solve a typical visual effects shot, such as putting a brand new screen on existing footage of a laptop computer with a handheld camera. We used mocha-AE to place the new screen over the old screen and we used Rotobrush to cut out a copy of the hands and place them in front of our brand new screen. But again, my point here was not just to show you how to solve this one particular shot, but instead to give you an idea of the workflow of how to tackle shots like this.
Because after all, every shot is different. You could of used tools other than Rotobrush to cut out the hands. For example, you could of used the, masking tool to go ahead and create mask shapes around the fingers, or you could of used the paint tools to go ahead and create an alpha channel for those fingers. Similarly, you didn't have to use mocha-AE to track that laptop. After Effects has other tracking tools, including Warp Stabilizer VFX. Before we go let me show you an alternate solution using that tool. If you have access to the project files, I hid that solution inside the comp's Progress Points folder.
It's called Work Stabilizer VFX Starter and Finished. I'll open up the starter. And, here we have the same thing we had before the Control Panel and our laptop computer. I'll select the laptop just like before. But, instead of using animation tracking mocha-AE, I'm going to use Warp Stabilizer VFX. Warp Stabilizer is usually used to smooth out the camera motion in a shot, but it can also be used to temporarily remove the camera motion, apply additional effects to a layer, and then put that original camera motion back in.
I'll apply Warp Stabilizier VFX. It'll take a little while to analyze this shot. And frankly, it's going to have a little bit of trouble with this shot. This person is moving in a contrary direction to the way that the screen is moving. Therefore, we may not get a particularly good stabilization. And, you see we have a bit of a fun house mirror effect here. Warp Stabilizer VFX, underneath its advanced section, has the ability to show and, therefore, delete undesired track points. And I am going to delete the track points that are on his body so the Warp Stabilizer VFX is only looking at the nailed down things in the room, the laptop, the wall, the lamp, the pencil dispenser, etcetera.
That way it will stabilize the correct elements of the shot. I'll go a little bit later in time where more of these undesired track points appear all over his face, like a bad case of the mumps, and I'll keep cutting those out, leaving behind only the non-moving elements in the room. Lets go a little bit later. I don't need to get every single bad point. I'm just trying to tip things in warp stabilizer's favor by giving it more good points, than bad points. That will improve the accuracy of my track.
Go a little bit later. Delete some more undesired points, including the ones on his hands which are constantly moving. And, let's go to the end of the shot and remove these few remaining rogue points. There, there, and on his hands. Once we're done stabilizing, if I turn off the track points and try to lock down my camera by changing the stabilization result to no motion, you'll see now we have a pretty stable shot.
And, that gives us the new opportunities to put something new in this scene. Okay, what I need to do is set Warp Stabilizer VFX to Reversible Stabilization. That means temporarily lock off the camera, show me the entire shot, and then I can start applying things back into the shot. It's restabilizing. And, you can see I've got some black border around the edges, because it's trying to preserve as much of this shot as possible. Normally, you use reversible stabilization by applying more effects to this stabilized layer and then putting the camera move back in.
However, you can also use it with adjustment layers. I'm going to select my new control panel, turn it on, apply effect, distort, corner pin. I could also use the CC Power Pin, which is a slightly better version of this effect. And, just for fun, let's go ahead and use that. Now I'll drag the corners of my new control panel onto the corners of my stabilized laptop. That corner, and just like we had to do before, since I can't actually see that corner, just make it look somewhat correct.
Like around there. Maybe pull that corner out a little bit more. Once I've pinned my new screen to the laptops stable location, I'll create a layer, new, adjustment layer. You can apply effects to adjustment layers, and they in turn process the composite of everything underneath, our stabilized footage and a control panel. I'll go back to my warp stabilizer. Copy that effect which already has all the stabilization data in it. Go back to my adjustment layer. Paste it in. Ignore this warning, and change advanced objective to reverse stabilization.
Put that track camera move back into the shot. And now, you'll see that I've returned to the original camera movement and have my data display over that laptop. Another solution to the problem. From here I do the same thing as I showed you earlier in this course. I'd use a compound type blur, like camera lens blur, to blur this new screen. I'd do a little bit of color correction on it, and find some way to cut out these hands and put it over this new screen.
This course was created and produced by Chris and Trish Meyer. We're honored to host this content in our library.
- Tracking in mocha AE
- Corner pinning in After Effects
- Rotoscoping with Roto Brush and Refine Edge
- Matching color and depth of field
- Reversible stabilization with Warp Stabilizer VFX