Apple Shake 4 - Manual (Page 785)

Chapter 26 Transformations, Motion Blur, and AutoAlign 785
As you can see in the above example, the resulting image may have an irregular border,
depending on the amount and position of overlap, and the warping required to
achieve alignment. If necessary, the border can be straightened with a Crop node.
Aligning Overlapping Images
You can also use this node to align two images that almost completely overlap. An
obvious use of this is to align an image with something in the frame that you want to
remove with a second “clean plate” image. After you’ve aligned the two images, you
can use the aligned output image as a background plate for use in a paint or roto
operation to remove the unwanted subject.
The primary advantage of the AutoAlign node in this scenario is that it allows you to
precisely align a clean plate image to an image sequence in two difficult types of
situations:
• If the clean plate image is from a different source, or has different framing or other
characteristics that make it difficult to align using regular transformations
• If the target image is in motion, and alignment is difficult using regular trackers
For example, if you have the following shot of a man jumping across a bottomless
chasm, with the camera moving dramatically to follow the action, it may be difficult to
line up a still image clean plate.
Moving camera with unwanted safety rigging Still image clean plate