Apple Shake 4 - Manual (Page 753)

Chapter 25 Image Tracking, Stabilization, and SmoothCam 753
tolerances
The tolerances subtree contains subparameters that let you control this node’s
behaviors when the tracking quality decreases.
matchSpace
Not to be confused with the matchSpace parameter above—the matchspace subtree
has three subparameters with sliders that let you weight how closely the tracking
operation follows each color channel of the image being tracked. In general, the color
channels with the most contrast for the feature you’re tracking should be weighted
most heavily. Color channels with minimal contrast for the feature you’re tracking
should be de-emphasized.
preProcess
This button turns on preprocessing for the tracking area, applying a slight blur to
reduce fluctuations due to grain. To control the blur amount, open the preProcess
subtree.
• blurAmount: A subparameter of preProcess that sets the amount of blur applied
when preprocessing to improve the quality of tracks in clips with excessive grain or
noise.
track1Name, track2Name…
The name of the track, itself a subtree of parameters containing the data for that
particular tracking region. To change the name, click in the text field and enter the new
name. The number of tracks corresponds to the number of tracking regions you’ve
created using the Add and Delete buttons. Each trackName parameter contains the
following subparameters:
• track1X: The actual X value of the keyframed track point at that frame. Use this to
link a parameter to a track point. This parameter defaults to the expression width/3.
• track1Y: The actual Y value of the keyframed track point at that frame. Use this to link
a parameter to a track point. This parameter defaults to the expression height/3.
• track1Correlation: The correlation value representing how closely that keyframe
matched the original sample. A score of 1 is a perfect score. 0 is an unusable score.
• track1 Window Parameters: The parameters within the track1Window Parameters
section define the size and position of the tracker boxes used to perform the motion
tracking analysis. Each of the position and sizing parameters in this section is
transient, meaning they’re not saved with the project. If you close a project, these
parameters return to their defaults when that project is reopened. The following are
the default expressions that each parameter is set to.
• track1Left: width/2-height/30
• track1Right: width/2+height/30
• track1Bottom: height/2-height/30
• track1Top: height/2+height/30
• track1leftSearch: width/2-height/15
• track1RightSearch: width/2+height/15