Apple Shake 4 - Manual (Page 827)

Chapter 27 Warping and Morphing Images 827
Connection lines can be moved, and even animated, to control the speed and direction
of deformation. Additional connection lines may also be created to give you more
precise control over the deformation itself.
Using Boundary Shapes to Limit Deformation in an Image
The Warper and Morpher nodes both work by pushing and pulling pixels from the
region of an image defined by the source shapes to the region defined by the target
shapes. When part of an image is warped, the surrounding area stretches to
accommodate the change, as if the image is on a sheet of rubber being pushed and
pulled to distort it.
The region affected by the resulting deformation is not limited to the area defined by
the source/target shape pairs. In fact, you’ll notice that a significant area of the image
surrounding each source/target shape pair is also deformed. While there is a 100
percent displacement at the actual position of the source and target shapes, the total
area of deformation lessens gradually with the distance from the shape pair. This may
result in a warp or morph not only affecting the intended subject, but also the
surrounding background.
This aspect of the Shake warper is useful in that it helps to smooth the transition
between the warped and unwarped parts of your image, resulting in a more realistic
effect. It also means that sometimes it’s not necessary to create as many source/target
shape pairs as you might think—a single shape pair’s area of influence may be enough
to create the effect you want.
On the other hand, there are usually parts of an image that you don’t want warped. For
example, if you’re warping someone’s eyebrows, chances are you don’t want his or her
hair to be distorted as well. You exclude parts of an image from being affected by the
Warper or Morpher node using boundary shapes.
Warp without boundary shape