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Explore how to use the motion tracker and stabilizer built into After Effects and shows how to handle a variety of shots. Author Chris Meyer leads a quick tour of the third-party software mocha and demonstrates the workflow for The Foundry's KEYLIGHT, both bundled with After Effects. The course also covers tracking a greenscreen shot with a handheld camera and replacing its background.
The After Effects Apprentice videos on lynda.com were created by Trish and Chris Meyer and are designed to be used on their own and as a companion to their book After Effects Apprentice. We are honored to host these tutorials in the lynda.com Online Training Library®.
I am going to start out by demonstrating the brand-new Warp Stabilizer, which was added in After Effects CS5.5. For many shots, this is as close as it comes to just applying an effect and you're done. However, there are ways of tweaking it if you want to improve its performance and conversely, there are some shots that doesn't work so well on. If you have access to the Exercise Files, open up the comp WS-Warp Stabilizer starter. In it we have a shot of an elephant walking across the plain. I am going to cue up a RAM preview of this shot, and you'll see that the camera has a fair amount of bounce to it.
There's also bit of a jerk at the start and stop of the camera movement, and notice how it bounces up and down here at the end; stops and bounces. Let's say we want to smooth out this camera movement as if it was on a nice heavy tripod with a fluid head. I am going to select my footage, open up Window>Tracker, and in After Effects CS5.5 click Stabilize Motion. In After Effects CS6 and later, there is a dedicated Warp Stabilizer button in this dialog. When I click Stabilize Motion, the first thing After Effects is going to do is analyze every frame of this shot.
It's looking for a motion of what it would call Primary or Foreground object versus the motion of the background. It's doing this so we can treat them separately and decide which one it wants to keep stable while the other one is allowed to move. The Warp Stabilizer is also capable of doing some perspective warpage of these components to help remove some parallax errors as the camera moves around the scene. Now you notice that this is performing a fairly automatic stabilization. One of the nice things about the Warp Stabilizer, however, as I can go ahead and open up other compositions and work on them while the Warp Stabilizer is performing sky collections in the background.
When I am done working other comps, I can go back to this one and it will be finished. I'll select my footage, press F3 to bring the Effects Control Panel forward, and you'll see the Warp Stabilizer effect has been applied to this shot. I'll cue up another RAM preview. Since the footage has already been analyzed and stabilized, it happens pretty quickly, and now you see we have a much smoother camera movement. We don't have the up and down bounce during the course's camera movement, and we have a lot smoother take off and ending to this pan as well.
Just to compare, I am going to turn the Warp Stabilizer off for a moment, preview again, and now you'll see the degree of bounce going on in the footage as well as this jerky motion here at the end where the camera hits its stop but the elephant keeps moving. Warp Stabilizer back on and the result is a smoother shot. Now for many shots this may be all that you need, however, there's a couple of quick adjustments you can make before you dive in deeper and really start tweaking out what Warp Stabilizer can do.
One is the Smoothness parameter. You'll notice that by default Warp Stabilizer does not lock off the camera shot, it does not keep the background entirely stationary or the elephant entirely stationary. Instead, it attempts to smooth the motion in the shot rather than remove any motion in the shot. You can adjust the amount of smoothness in that camera movement. For example, I'll increase this to 200%. Yes, you can go over 100%. It's already analyzed the footage, it just needs to take the data that's already analyzed and applied to re-stabilize the shot, it has to come up with a new camera pan movement and a new scale of the footage to take into account the smoother camera movement that we've just requested.
I'll cue up another RAM preview and now we have a much more gradual take off to the camera movement and a much smoother pan with even less bounce up and down. The cost of having smoother movement is that the Auto-scale parameter, the amount the Warp Stabilizer needs to scale up the footage so no edges get exposed while smoothing up the camera shot has increased. When I had a Smoothness value of just 50% you'll see it does not need the Auto-scale by quite as much to keep the footage in the frame all the time.
And this problem of keeping footage framed is something we will really discuss in the next chapter when we work with a Point Stabilizer and Tracker. But what if you did want a completely locked off shot? Increasing the Smoothness value won't get you there; you cannot get too infinite smoothness, which means locked off. Instead, you'll want to use the Result pop-up which has two choices: Smooth Motion or No Motion. A locked off camera isn't always desirable, for example in this case, which is a continuously panning shot, we're not trying to remove camera jitter on what is an otherwise stable shot.
We're trying to smooth out a pan. In this particular case, if I was to pick No Motion, After Effects is going to have to really scale up a shot and still end up with blank gaps on left and right. The background will be stable with the elephant walking through the shot, but not much of the shot would be usable. There are ways to work around this and that's what I am going to be talking about in the next movie; tweaking out these other parameters such as Borders and the Advanced section. But if all you have is a handheld camera, that should have been on a tripod and should not have been panning, maybe No Motion is what you want.
I find I am personally going for Smooth Motion these days just because it provides a more organic shot rather than something that looks artificially locked off.
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