Create a digital double in Final Cut

Combine an animated mask with the classic split screen effect to turn one person into two


Since the middle of the 20th Century, movie makers have enjoyed using the split screen technique to make a person look like they’re on screen with their identical twin. Variations of this classic technique are employed today in dramas such as Orphan Black, where the protagonist encounters multiple copies of herself.

The split screen technique is simple but effective. You film an actor in the right half of the screen pretending to talk to their twin in the left half. The actor then moves to the left of the frame and pretends to chat with the twin on the right. You run the two clips together and use a graduated mask to mix the left half of the one shot with the right half. This lets the ‘twins’ interact simultaneously.


1 Create a new event

Choose File>New>Event. Name it ‘Twin Event’. Tick Create New Project. Click OK. Choose File>Import>Media. Select our five clips and click Import Selected. Add them to the Twin Event.


2 Add right twin

Drag the Right Twin clip to the Timeline. The man gives the right twin someone to interact with. Go to the Inspector’s Audio panel and drop the clip’s volume to 0 to hide his voice.


3 Add left twin

Drag the Left Twin clip to the Timeline so that it runs parallel with the Right Twin clip. Both clips run simultaneously, but we can only see the top Left Twin layer at this stage.


4 Add graduated mask

Click Show Effects Browser>Keying. Drag the Graduated Mask onto the Left Twin clip. This makes the bottom of that clip transparent, revealing part of the clip on the layer below.


5 Create a vertical split

Go to the Graduated Mask section of the Inspector. Toggle open the Target attribute. Set the X slider to 0.6 px. Set Y to 0.5 px. This creates a vertical split revealing both twins.


6 Slide the mask left

Toggle open the Graduated Mask’s Center attribute. Drag the X slider to 0.37 px. This pushes the mask to the left, hiding the left twin’s duplicated wine glass for the moment.


7 Add the first keyframe

Scrub the Playhead to 17.03, just before the left twin reaches to take the glass. In the Inspector, click the Target’s Add a Keyframe icon. Click the Add a Keyframe icon for Center, too.


8 Animate the mask

Scrub the Playhead forward to 17.11, as the
left twin takes the glass. In the Inspector, set the Center attribute’s X value to 0.5 px. A new keyframe will be added to the Center attribute.


9 Test the animated wipe

When you play the sequence the mask’s keyframes cause the split in the screen to slide so both twins can handle the wine glass in a single shot. Add the cutaways clips for variety.

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