Tracking and Translating

Tracking and Translating

There seems to be no way to motion track a mask (other
than the aforementioned TrackerViz) nor to move a set
of Mask Path keyframes together. Here are some workarounds
that help when a mask needs to move:
. If movement of a masked object is from camera motion
and occurs in the entire scene, you can essentially
stabilize the layer, animate the mask in place, and then
reapply motion to both. Chapter 8 goes into more
detail about this.
. To translate an entire animated mask, you can make
the masked layer a track matte applied to the same
layer (without masks); you can then track or translate
the entire track matte.
Mask shapes can be linked together directly with expressions.
Alt/Option-click the Mask Path stopwatch, then use
the pickwhip to drag to the target Mask Path. Only a direct
link is possible, no mathematical or logical operations, so
all linked masks behave like instances of the fi rst.
Mask Motion Blur
To mask motion blur would seem to be something of a
nightmare, as its edges defy careful observation. It’s not
easy by any means, but masks respect the motion blur
settings of the composition; a masked element in motion
can be set with motion blurred edges that obey the same
composition settings as any other animated element.
That means you have a chance of matching the motion
blur using a mask whose contours would fi t the shape of
the object in its stationary state (Figure 7.6). To make the
mask work with the moving element is a matter of getting
the composition’s Shutter Angle and Shutter Phase settings
to match.