Wire Removal

Wire Removal

Wire removal and rig removal are two common visual
effects needs. Generally speaking, wire removal is cloning
over a wire (typically used to suspend an actor or prop in
mid-air). Rig removal, meanwhile, is typically just an animated
garbage mask over any equipment that appeared
in shot.
After Effects has nothing to compete with the state-of-the-art
wire removal tool found in The Foundry’s Furnace plug-ins

(which sadly are available for just about every compositing
package besides After Effects, although Adobe did license
the Kronos toolset from Furnace to become Timewarp).
The CC Simple Wire Removal tool is indeed simple: It
replaces the vector between two points by either displacing
pixels or using the same pixels from a neighboring frame.
There are Slope and Mirror Blend controls allowing you a
little control over the threshold and cloning pattern, and
you can apply a tracker to each point via expressions and
the pickwhip (usage described in Chapter 10).
The net effect may not be so different from drawing
a two-point clone stroke (sample the background by
Alt/Option-clicking, then click one end of the wire, and
Shift-click the other end). That stroke could then be
tracked via expressions.
Rig removal can very often be aided by tracking motion,
because rigs themselves don’t move, the camera does. The
key is to make a shape that mattes out the rig, then apply
that as a track matte to the foreground footage and track
the whole matte.

Dust Bust

This is in many ways as nitty-gritty and low-level as rotoscoping
gets, although the likelihood of small particles appearing
on source footage has decreased with the advent of
digital shooting and the decline of fi lm. Most of these fl aws
can be corrected only via frame-by-frame cloning, sometimes
known as dust busting. If you’ve carefully read this
section, you already know what you need to know to do this
work successfully, so get to it.

Conclusion

And so, like rain, into every effects artist’s life a little
rotoscoping must fall. The tools outlined here are mostly
suffi cient for the type of rotoscoping work that compositors
will have to do. Dedicated rotoscope artists would
likely choose software other than After Effects or perhaps
employ Silhouette as an After Effects plug-in. As long as

rotoscoping isn’t your stock in trade, however, the After
Effects tools will usually allow you to fi nish the shot without
having to look for other software.
The next chapter completes the picture by adding motion
tracking to your areas of expertise. As mentioned,
motion tracking plus rotoscoping can equal a shortcut
around tedious tasks.