Getting Wires Out

[jadeallencook]

I've been watching some B-Roll footage and I've been seeing them use this technique a lot where they attach wires to the actors to make them fly, jump, etc. Here's a perfect example.

https://www.youtube.com/watch?v=5XOqhJGz5rA

My only question is, how do they get the wires out? Do they rotoscope them out? But what about when the camera is moving? You can't really rotoscope that? Where do they go?! Frame by frame extraction is the only thing I can think of!

 

[danjenkins]

Every compositing package I know of has wire removal tools. It's a ubiquitous tool these days. Most work the same way, you basically roto the end points of the wire and it samples the nearby pixels to fill in the pixels of the wire.

And you seem to be misunderstanding what Rotoscoping is. Roto IS frame by frame extraction. Roto takes many forms and is used in dozens of different ways, but at it's core Rotoscoping is hand animating a matte for extracting elements.

 

[novicemonk]

Once upon a time DPs had to attempt to hide wires with careful lighting, or even smearing Vaseline on the lens (more likely optical flat). These days, it's much easier and more straightforward to digitally "remove" wires in post. As danjenkins said, most compositing packages have a wire removal tool. I believe After Effects has one.

I have used for some years a software called "Pinnacle Commotion". It offers two approaches to wire removal. The first "seam", takes the pixels either side of the wire, and duplicates them over the wire. The other, "replace" involves selecting the pixels occupied by the wire and replacing them with the corresponding pixels from either an earlier or later frame or a "clean plate shot" (a shot without the wire).

Both approaches have pros and cons.

Seaming works well with fast moving action, where the camera is moving quickly, or the person travelling is. A good example would be if a person is flying across frame, and behind them is a clear, blue sky. Duplicating pixels of blue sky, is unlikely to look blurry or smudgy to the audience. A static shot of a person flying past a brick wall might not work so well.

Restoring often works best in slower action. For example, if you wanted to shoot a static shot of a person levitating, then floating in the air, you might first lock off the camera and film a clean plate shot (sans wires or performers). Then shoot the wire action. The clean plate acts almost like a lower layer in Photoshop. As you erase the pixels occupied by the wires, you reveal the pixels of the clean plate shot.

Wire removal is roto, but a certain amount of it (using the right software) can be automated. Thicker, safer wires and ropes can be used, especially with good clean plates. In some instances, blue or green ropes are used, and painted out rather like with blue or green screen processes.