Holograms in the Star Wars movies have a few things in common: they’re blue, they involve some sort of video distortion, and they’re semi-transparent. However, there is also a lot of room for variation in the holograms: while they all share the blue tint, some retain their original flesh tones, while others appear to be based on desaturated footage. Some have an outer glow, some don’t. The interference patterns vary as well. All that said, I settled on one look and tried to duplicate it, knowing that there was some latitude for variation from the movies. I figured that if anyone pointed out a discrepancy between Duality’s hologram with those in the Star Wars films, I could just plead that it was because we had a defective holographic emitter!

The Interference
I started by creating the interference pattern (using Adobe Illustrator) as two separate layers: the thinner lines and the thicker lines. These two layers were then brought into After Effects where they were animated, both scrolling downward (the thicker-lined layer moving considerably faster than the thinner one). The thicker-lined layer’s opacity was also varied on a frame by frame basis. This was rendered as an eight second animation (1.2 MB QuickTime).

Keying the Subject
Next, I imported the footage of the hologram subject (Mark as Darth Oz) into a new After Effects composition. I keyed out the blue background (it wasn’t necessary to be too careful with this operation, as the edges of the hologram are destined to be blurred and mucked with. Blue spill is also not an issue, as the footage will eventually be bleached of all color and then tinted blue, anyway).

Once a satisfactory key was achieved, I rendered the footage out as a new animation with its own alpha channel.

Merging the Subject and the Interference
All of the relevant footage was then brought into a new composition: the plate, the holographic interference, the keyed footage with the alpha channel, and the matte bars.

To get the interference to adopt the shape of the keyed footage, I clicked on the Switches / Modes button at the bottom of the Time Layout window in order to access the Track Matte pull-down menu, from which I selected the keyed footage layer (in this case, “shot 41+alpha”).

Doing so caused the interference layer to adopt the transparency information dictated by the keyed layer’s alpha channel.

To get the keyed footage to re-appear, I toggled that layer’s video button (the little eye icon to the left of the footage layer).

I adjusted the opacity of each of the layers independently of one another: the interference layer to 30% and the footage to 50%. For this particular shot, the interference was also scaled up to 150% of its normal size, as the camera is slightly closer to the hologram.

Color Adjusting
I found that each clip required quite different settings to keep the holograms consistent. This was due to different lighting levels that were present when the footage was filmed. Because the settings were so varied, naming the exact settings that I used in any one shot for Duality is pointless. My suggestion if you're following this overview to create your own hologram: tweak to taste. However, it was usually some combination of the following filters that got me the look I was after (the filters with he CW prefix are from the Composite Wizard plug-in set):

Further Distortion
Holograms in the Star Wars universe are plagued by other kinds of distortion besides video interference. In order to reflect that, I added some “ghosting” and “fizzling.”

Once again, I rendered out the footage with an alpha channel, first turning off the plate layer and the matte bars layer (you will find that running so many filters slows down computer performance by quite a bit. Pre-rendering the effects on a particular layer when you’re satisfied with the look of those effects is a big time saver, especially when you’re not done experimenting with other effects that need to be applied to the layer). I then imported the newly rendered animation, and turned off the ones used to create it (I don't like to delete such layers. Instead, I keep them in the composition turned “off” so that they’re handy in case I need to adjust something).

Ghosting was accomplished by duplicating the hologram layer and re-positioning the duplicate slightly to the right of the original. At arbitrary points in the animation, I key-framed in variations in the opacity of the duplicate, alternating between 0% and 100% over several frames. This gives the hologram the appearence of “skipping” side ways.

The “fizzle” is created by the Wave Warp Filter (Effect>Distort>Wave Warp). Keyframing the settings gives the hologram a “jittery” look.