Unless you've been living in the Amazonian rain forest for the past 30 years, you're probably familiar with the Star Wars hologram transmission effect, first seen in the first Star Wars film (now known as "Episode IV: A New Hope"). You can see a good example of it here:
There have been many versions and variations of this effect over the years, both in the Star Wars films themselves and elsewhere, so much so that it's become an iconic effect in its own right. But in general, the effect consists of shot footage of a subject speaking, isolated from its background, and seen as a translucent, blue-tinted, glowing image. Often, you'll see scanlines, noise, and "transmission error" artifacts or glitches in the image as well.
In this Feature Tutorial, I'm going to show you my own take on the effect using just Adobe After Effects, with no third-party plugins or apps, which should help get you started on the path to creating your own. My friend and neighbor Jordan Rudess has been kind enough to offer himself as the subject for our transmission, so let's get started with masking the footage
There are two major parts to creating this effect - first, we'll need to isolate the subject from his background, and then we'll need to apply the various effects and treatments that will give us the final hologram illusion.
Now, the easiest way to mask or isolate video footage is to shoot your subject against a well-lit greenscreen or bluescreen backdrop (making sure that your subject doesn't contain any colors close to the background color), then use After Effects' Color Keying tools to make the background transparent. With the right kind of footage, it can be a simple one-click procedure. Most of us don't have the luxury of working in a bluescreen studio, though, so we'll have to mask, or remove the background from, the footage manually. Fortunately, After Effects has some automated tools that will make this much easier than individually drawing a mask for every single frame.
Here's the raw footage of Jordan speaking, shot against a white wall in my home:
You'll notice that he's fairly well-defined against the background. However, there isn't really enough contrast between him and the wall to let us use either the Luma Key or Color Key effects to remove the background - I know, because I tried them both. So, we'll have to mask him by hand. Fortunately, though, recent versions of After Effects have included the Roto Brush tool, a semi-automated masking method that will work well for us here. Here's how it works.
For best results with the Roto Brush tool, your footage should have its subject well-outlined against a plain solid background, with high contrast between the foreground and background. Import your footage into After Effects, and drag it onto the Create A New Composition button at the bottom of the Project window:
This will make a new Comp that matches the footage's format. I'm calling this Comp Jordan Head Roto.
Click on the Roto Brush tool in the Toolbar:
Double-click with it on the image in the Comp window to open the Layer window - all Roto Brush work happens in the Layer Window:
Next, step or drag through your footage with the Time Marker at the bottom of the Layer window to locate a frame where your subject is as clearly defined as possible. This is called the base frame, and it's the frame where you'll define your initial outlines. It's often the first frame, but doesn't have to be. Once you've located your base frame, draw a stroke with the Roto Brush tool (the tool will appear as a green circle with a plus in it) down through the center of your foreground subject:
(Contrary to what you might first think, you don't use the Roto Brush to outline the subject - all you need to do is define the center of the object you want to outline.)
Release the mouse button, and the Roto Brush tool will outline your subject with what's called the segmentation boundary - the magenta line around the subject's edge:
As you can see, the Roto Brush has done an excellent, even somewhat miraculous, job of outlining Jordan's body. Because his lower right arm is pretty dark, due to the uneven lighting in the room, it didn't catch that, but still, for one click and drag, it's pretty good. Believe me, it's much less tedious than drawing the mask by hand with the Pen tool. And we can easily fix that little glitch.
Now let's fix the areas around Jordan's right arm where the segmentation boundary needs tweaking - it's important to get your base frame as clean and accurate as possible, because Roto Brush will base all its future calculations on this frame. So, we want to both add Jordan's bare right arm to the segmentation boundary selection, but also remove the area between his right arm and his body.
To add his right arm, just drag another stroke with the Roto Brush through the center of that area:
which will add that area to the boundary:
Next, hold down the Option key (the Roto Brush tool will change to a red circle with a minus sign in it) and drag in the area between Jordan's arm and body:
which will delete that area from the boundary:
As you can see, this also removed some of Jordan's body from the boundary area, so to fix that, we just need to drag again with the regular (green) Roto Brush in that area:
to add it back again:
And that should do it. We can check the alpha we've just created by clicking the Toggle Alpha button at the bottom of the Layer window:
and check the state of our mask by clicking the Toggle Alpha Overlay button in the same area:
which overlays a translucent color into the alpha channel.
Now that we've defined our base frame, let's move on to masking the rest of the clip. The Roto Brush does this automatically in a process called propagation, in which the base frame mask we've defined is copied and adjusted on subsequent frames. The range of frames within which the propagation occurs is called the span, and we adjust the span to adjust the propagation range.
Now, with complex subjects, you often want to set a short span, so you can precisely tweak the segmentation boundary. In our case, though, because there's relatively little motion in the footage, we can set the span to cover the entire clip, and tweak later if necessary.
So, to adjust the span, click on the end of the span (the block of gray frame markers below the Time Ruler):
and drag it out to the full length of the clip:
We can start by just hitting the Space bar to start the propagation process. When we do, the clip will start playing (slowly), and you'll see the magenta segmentation boundary auto-magically follow Jordan's outline as he moves. You can also, if you prefer, just hit the Page Down key (if you have one) or Command-Right Arrow to step through the clip one frame at a time. As you do, you'll notice that certain areas may drop out of the boundary, depending on your subject's motion, as in these two consecutive frames:
If that happens, just stop on the problem frame and, as before, either drag with the Roto Brush tool in the area to add it to the boundary, or option-drag to remove areas from the boundary. Then continue to step or play through the footage, propagating and adjusting as you go, until you get to the end of the clip. You can also step backwards if you like to adjust previous frames as well.
Once you have the segmentation boundary adjusted to your liking, you'll want to freeze the propagation. Freezing caches the segmentation boundary to disk and prevents further segmentation propagation, which will ensure that your adjusted boundary stays in place and which also speeds up any further interaction with the mask. To freeze the segmentation boundary, click the Freeze button below the Time Ruler:
Freezing the boundary will take a while, but when it's done you'll see an indication in the Layer window that Roto Brush segmentation is frozen. If you want to adjust the segmentation at a later date, you'll need to unfreeze the boundary by clicking the Freeze button again.
Our final step in Part 1 is to refine the mask we've just created with the Roto Brush.There are a number of tools in After Effects for adjusting masks, but the Roto Brush tool has its own Refine Matte section in its Effect Controls, which is what we'll use here. To view those controls, select the layer you've been working on in the Timeline window and click the Effect Controls tab next to the Project window. You'll see the Refine Matte controls:
Now, we don't need to go into a lot of detail about the Refine Matte tools at this point, but we do want to take a look at the Smooth and Feather controls. Increasing Smooth will do just that - smooth the edges of the mask we just made to reduce any sharp edges we may have created during the propagation. You don't want to get carried away here - a too-high Smooth setting will just turn the mask into a blob:
A little smoothing can help reduce the roughness that sometimes results from using the Roto Brush. A setting of 3 or 4 should be sufficient.
Also note that if you see a little too much of your background around the edges of your subject, you can try increasing the Choke value, which will bring the edges of the mask in tighter around the subject. You'll probably want to do this in Toggle Alpha Overlay mode, so you can see the effect of choking the mask.
Finally, and most importantly, we want to crank our Feather property up to perhaps 50% or more. This will soften the edges of the alpha channel and help blend it into the
background, which will help give us a softer, fuzzier look to our final Hologram effect - that edge fuzziness is one of the characteristics of the look. So set your Feather to say 50% or so, so that your mask looks something like this:
We can always adjust this later of course, when we start putting the effect together, but this is a good start.
Alright! We're finished with Part 1 - we've masked Jordan with the Roto Brush tool to isolate him from his background, and now we're ready for Part 2 - creating the Hologram Effect.
Want to learn more? Richard has a bundle of excellent After Effects Training videos here!