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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®.
Quite often the Warp Stabilizer can be an instant gratification effect. Apply it, you have instantly a better shot, and you can move on. However, it doesn't always work the way you expect, and sometimes you might want to tweak out or improve its performance. So let's discuss these additional parameters and when and how you would use them. We discussed Result and Smoothness in the previous movie. Next is Method. The Default Method Warp Stabilizer uses to stabilize a shot so it actually tries to bend the pixels in the background and foreground separately to remove anything such as parallax distortion just because the camera might have been shifting left and right during the course of the shot.
If however you notice the parts of your frame are looking a bit rubbery or distorted, that's some unwanted artifacts caused by Subspace Warp. You have other choices that basically make Warp Stabilizer less sophisticated with the benefit of causing less distortion in your shot. For example, Perspective treats the entire frame just as one solid sheet that can be tilted, panned, etc., but does not treat some pixels differently than others. If even that causes some unusual wavering back and forth or tilting of the image, you can go down to simpler solutions such as just Position, Scale, and Rotation with no perspective tilting of the shot.
And I'll cue up that RAM preview just to give an idea what that looks like. In this shot there's not a huge difference between that choice and the Subspace Warp. And finally, if you don't even want any scaling or any rotation going on, you can stabilize just Position. This is kind of equivalent of the most basic Point-based stabilization that we'll show in the next chapter. I'll go ahead and preview that.
And again, for a simple shot like this you're not going to see a lot of difference except for a little bit of tilting of the shot but it's still pretty clean. Since it worked out well, I'm going to keep Subspace Warp. Next comes Borders and how you frame a shot. By default, Warp Stabilizer looks at its smooth camera movement and says, well, if I smooth out the camera in this way I am going to have some exposed edges around the shot.
How do I cover up for those exposed edges? One way to do it is to scale up the layers necessary, it softens the shot but it covers the edges, and then do additional cropping as necessary to make it fit the frame. If you don't want any scaling, if you don't want your shot being softened at all, you can just stabilize and crop. And this is where you get to see what's really happening with the shot. Warp Stabilizer is having to move things by this many pixels up, down, left and right to keep nice, smooth camera movement in the shot.
And this where when I go to higher smoothness values, you see the trade-off. It needs even more pixels buffer on the edges to keep the shot centered or at least smoothed out. At least it does perform a nice automatic cropping so you don't have wandering edges on your shot and now you can use this to say a picture in picture element or scale it to your own taste. Less sophisticated than that is Stabilize Only, and this is where you get to see the result of just stabilizing the shot but not cleaning up the edges.
The cleaning up the edges part is usually one of the biggest challenges of stabilizing a shot. So it is nice that Warp Stabilizer can do this automatically for you, but if you are the type of person who likes to make manual decisions, that's what Stabilize Only is for. There is also an Advanced Solution called Stabilize and Synthesize Edges. What this does is it keeps your scale at 100% and to cover any missing material around the edges it looks earlier and later in time for pixels that might have fleetingly appeared in shot then disappeared again, copies and pastes them from a different time to the current time to fill in the edges.
I'll select that option. It'll take a little while to think about it. But when it's done you'll notice that the Scale remains 100%, Auto-scale is grayed out, and now we have much less edge exposed than we did earlier. I can move to different points in time early in the shots when you're going to have your biggest problem, during the middle of the shot you have less problem. If you still have gaps around these edges, the best solution is to scroll down the Advanced section and try increasing the Synthesis Input Range.
Right now it's only looking at half second earlier and later in time to fill in those gaps. But if we allow it to look further, say 2.50 seconds earlier and later, it'll need to do some calculations to go find those pixels but now there'll be a greater chance that it actually fills in those gaps around the edges. Now we have a smaller gap here. We'll still have a gap at the beginning because there are no pixels earlier in time to borrow from. But in general, the shot will be filled in better. If necessary, you can manually scale the shot to fill in those remaining gaps.
And I can probably get by if something small like only let's say 102% or maybe even 101. This shot happens to be very clean around the edges, so there is no problem using edge material for different points in time. If, however, you have a shot that has a bit of gunk around the edges - maybe it was a video tape transfer or a film transfer that's not cleaned around the edges, you can feather in the new edges over the old material and you can even crop out some of the gunk that was in the original frame.
I particularly need to do this with say, Beta cam or DV captures which may have some garbage around the edges. There is just a few more options to look at. When you choose the Auto-scale option, you can set what is the maximum amount it will scale up. You can also say, look, I know that the bezel on the TV is going to cut out some of these edges, so I am willing to have some material left around the edges with the benefit of less scaling taking place in the shot.
You might have gone away with this with standard def TV when the bezel definitely covered a lot of the frame. With today's high-def televisions and flat screen displays, you really don't know how much is going to be covered by the bezel. The user might even set it to be 0% so I would not use that in today's environment. Rolling Shutter Ripple, the Warp Stabilizer tries to take into account a phenomenon in many cameras such as DSLRs where the top of the image was taken is different than the time that the bottom of the image was taken.
If you still notice some ripple, some jello cam effects in your footage, you can try the Enhanced Reduction setting. However, After Effects CS6 now has a dedicated Rolling Shutter Repair plug-in that I'll look at in a later movie.
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