Learn the VFX Techniques Real Editors Use

These days, visual effects and graphics tend to find their way into just about every edit we touch, and half the time the audience doesn’t even realize it. Things like screen replacements, rotoscoping, object removals, and the always useful motion tracked text. As editors, we know they’re there because many times we’re the ones who made them.

When you think of visual effects, what comes to mind? Maybe it’s the stuff that’s completely CGI, like flying dragons, giant transforming robots, and whole fantasy worlds created inside the computer.

That’s all pretty amazing, but it’s a whole other level of expertise and not really what we as editors need to do on a daily basis. So maybe it’s working with some of the stuff that we mentioned earlier, but you know what I bet you’re not thinking of? Footage stabilization.

Footage Stabilization

Here’s a common scenario: you’ve got some footage, usually a handheld shot, and it looks great, but it’s super shaky and feels pretty unprofessional.

Depending on the editor, there are three options here:

1. Cut the shot into your timeline and then do nothing to fix it – not cool! Shame on that editor.
2. Apply a stabilizer in your editing software – this is what most editors would do. Depending on your software, your results will vary, and you’ll encounter different issues
3. Make just a little bit more effort and use some VFX skills to get it pretty close to perfect – let’s look at this option now

We’re going to be using After Effects because it’s inexpensive, easy to learn, and incredibly powerful. There are two methods we’re going to look at: advanced use of the warp stabilizer tool and the two-point tracking method. Let’s start with number one.

Warp Stabilizer

For you Premiere users, this is going to be familiar because After Effects also has a warp stabilizer tool. The problem with using just the Premiere stabilizer is that it sees the foreground in focus and the background out of focus, so it tries to stabilize the moving face of the woman in the foreground instead of the shot as a whole. This results in a lot of background distortion and a bad end product.

In Premiere, that would be game over – there’s nothing more you can do, but in After Effects, we can tell the stabilizer exactly what to stabilize and what to ignore.

So go ahead and select the warp stabilizer and open up the advanced tab (1). You might have tried to turn on the detailed analysis and run the track, but you’re going to end up with the same shaky result.

So instead, turn on ‘Show Track Points’ (2). Now the stabilization disappears for a second, but you’ll have all these little points over the footage (if they’re hard to see, increase ‘Track Point Size’ above 100%). Now that we’ve gone backwards in time to a point where the woman is close up in frame, and you can see a lot of track points on her.

And here’s the cool thing: you can simply select all these track points in a composition with a lasso, draw all the way around the ones that are on her face, hair and body, then simply delete them with the backspace key.

Go backwards and forwards in the clip just to make sure you don’t miss any points. Wherever they keep popping up, just move the playhead, circle them, grab them, and delete them. You can keep doing this even while After Effects is processing the footage.

The program should start to automatically realize what you’re trying to do with it. Once it’s done, the shot is much more stable. It feels like the camera is what’s been stabilized and not the motion of the woman who’s crying in our example.

Two-Point Tracking

If the warp stabilizer still doesn’t work for your shot, you can try the second method, which is two-point tracking. Start by duplicating the layer (CMD/CTRL + D), then turning off the warp stabilizer by deleting it, and turning off the layer underneath it so you don’t have to pay attention to it any longer.

With this top layer selected, use the tracker panel and select ‘stabilize motion’(1). You’ll have a choice between position, rotation, and scale(2). Since this is a handheld shot, stabilize just the position and the rotation because the camera is moving backwards from our actress.

Because we want to stabilize the shot as a whole, we’re going to track the background instead of the subject, but it’s out of focus. To make it easier for the trackers, zoom in and just enlarge these trackers quite a lot, then move the first tracker to the background, at a point of contrast(3).

This center smaller box should go around a distinct feature that you want After Effects to track. The larger box is the search region where it’s going to look for that feature. Think of the larger box like the tracker’s peripheral vision, just don’t make it too big because it’s going to get really, really slow, just large enough so that the tracked feature is still inside of the bigger box as you step forward or back by a few frames.

We’re trying to track two points that are across the screen from each other so that the tracker can get a sense of how the whole image is moving. We’ll make both boxes of the second tracker a little bit bigger and choose a point of contrast on the right hand side. Now we can go ahead and track forwards and see how it goes.

Once the tracking is complete, I’ll click ‘apply’ and choose ‘okay’. We’re going to see that the layer sort of moves out of the way. When we applied the tracking data to the clip, It’s added lots of keyframes to the anchor point position (and if we chose them, the rotation and the scale). I’ll now press ‘U+U’ to collapse the tracks again. Let’s look at the footage now:

It’s definitely keeping that background stabilized, but it’s not actually repositioning the layer for me so that I don’t see these edges. What I can do is select the top layer and find the point where the layer looks the most off. I can right-click and create a new null object(4), and then parent the layer to it(5).

Next, on the null object, I’ll open up the scale, position, and rotation properties and make an initial keyframe for all three of those, so anytime we move, rotate, or scale, the layer will automatically create keyframes.

Now I can  just move, rotate, and scale the layer as needed to keep this object pretty centered throughout the shot. Don’t make too many keyframes, just every couple of seconds when you see that things are starting to look off. Finally, I can select all these points and press F9 for easy ease, and then see how that looks:

So we have a similar but noticeably different type of stabilization here. You can pretty quickly and easily try both methods to see which works better for your particular shot. All it took was a couple of extra steps that the average editor probably wouldn’t either think to do or know how to do.

Keying footage

Now let’s take a look at another highly useful and common VFX technique for editors: keying footage. Just so we’re all on the same page here. Keying is a technique that creates transparent areas in footage based on its color (green screens) or its luminance (the black and white values in the footage)

This is useful for things like separating a subject or an object from the background, punching out areas like TV and phone screens, and allowing you to color correct different parts of the footage independently. Keying is a straightforward concept, but as with most things, there are challenges. Let’s look at a common example: separating a subject from a green screen.

Basic vs Advanced Keying

So here we’ve got this newscaster. On the left, we’ve got the result of using a color key in your editing software—pretty unacceptable. On the right, we’ve got a properly keyed shot using some additional tools and VFX knowledge.

When keying, you’re going to run into all sorts of issues. Keying is complex, way too much to fully get into here in this article, but I do want to give you an idea of how we approach it.

There are two important takeaways I want you to walk away with here: first, the specific effects that we used, and second, the overall key strategy.

The Four Effects

Here’s our newscaster in After Effects. We’ve made a mask around her, and I’ve turned the effects off

You can see that the raw footage is very flat – she’s on a green screen. Under the effects controls, we have a Lumetri color with a custom LUT that was given to me by Leon, one of our other trainers. Then we used Keylight. Let’s look at all the effects I used, one at a time:

1. Lumetri hosted our LUT and gave us control over the look of the footage—not so much used for keying, but an important step nonetheless when working with raw footage in After Effects
2. We used Keylight as the primary tool to punch out the green screen. Keylight has a lot more control over what is keyed out and what remains than you’re going to find in most editing software, so it alone is going to get us much further than a basic color or chroma key effect
3. Key Cleaner, which is used to refine the edges of our subject. When I activate that, it begins to clean up some of the edges
4. Advanced Spill Suppressor to eliminate the color cast from the green screen on our subject.

 

Key Strategy

Those are the basic effects, but what’s equally important when keying is the strategy, specifically in this case, keying the hair separately from the rest of the subject. The challenge here is the newscaster’s blonde hair. Hair is notoriously difficult to key, and blonde hair is the hardest, particularly against—you guessed it—a green screen.

Hence, I have a layer here that’s just the hair with the same effects but a bunch of different settings; they’re modified so we retain more of the detail on the hair. You can see that I masked this layer out just above her shoulders here, so all we’re getting is the hair.

Most of these effects have a boatload of settings to go with them. We’ll get into all those in another article, but if you can approach your keys using these effects and then remember to strategically tackle different parts of a key separately based on their specific issues, you’re going to end up with a pretty good result.

Wrap Up

Stabilization and keying are pretty big topics, but hopefully these last couple of techniques have given you an idea of what’s possible with a bit of VFX knowledge added to your editing skills.

The full VFX course we’ve put together is designed to empower you to create the types of visual effects and graphics that you’re going to need in your edits all the time, and it’s going to make a very big difference in the overall quality of your work and the professionalism of your final product. Click here to find out more.