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Motion tracking options
These settings apply to a tracker, a group
of track points that is generated in one tracking session. You can
modify these settings by clicking Options in the Tracker panel.
- Track Name
- The name for a tracker. You can also rename a tracker by
selecting it in the Timeline panel and pressing Enter on the main
keyboard (Windows) or Return (Mac OS).
- Tracker Plug-in
- The plug-in used to perform motion tracking for this tracker.
By default, this option displays Built-in, the only tracking plug-in
included with After Effects.
- Channel
- The components of the image data to use for comparison when searching
for a match for the feature region. Select RGB if the tracked feature
is a distinct color. Select Luminance if the tracked feature has
a different brightness than the surrounding image (such as a burning
candle carried through a room). Select Saturation if the tracked
feature has a high concentration of color, surrounded by variations
of the same color (such as a bright red scarf against a brick wall).
- Process Before Match
- Temporarily blurs or sharpens an image to improve tracking.
Blur reduces noise in the footage. Usually a value of 2 to 3 pixels
is enough to produce better tracks in grainy or noisy footage. Enhance
exaggerates or refines the edges of an image and makes them easier
to track.
Note: After Effects blurs or enhances the layer only
for tracking. This blurring does not affect the motion source layer.
- Track Fields
- Temporarily doubles the frame rate of the composition and
interpolates each field to a full frame to track motion in both
fields of interlaced video.
- Subpixel Positioning
- When selected, keyframes are generated to a precision of a
fraction of a pixel. When deselected, the tracker rounds off values
to the nearest pixel for generated keyframes.
- Adapt Feature On Every Frame
- Causes After Effects to adapt the tracked feature for each
frame. The image data that is searched for within the search region
is the image data that was within the feature region in the previous
frame, rather than the image data that was in the feature region
at the beginning of analysis.
- If Confidence Is Below
- Specifies the action to perform when the Confidence property
value is below the percentage value that you specify.
Note: To
determine an acceptable confidence threshold, track the motion and
then examine the Confidence values for the track point in the Timeline
panel for problematic frames. Specify a confidence value that is
slightly larger than the largest confidence value for the problematic
frames.
Select Continue Tracking to ignore the
Confidence value. This behavior is the default behavior.
Select Stop Tracking to stop the motion tracking.
Select Extrapolate Motion to estimate the position of the
feature region. Attach-point keyframes aren’t created for low-confidence
frames, and attach-point keyframes for the low-confidence frames
from previous tracks are deleted.
Select Adapt Feature to use the original tracked feature
until the confidence level falls below the specified threshold.
At that point, After Effects adapts the tracked feature to be the
contents of the feature region in the frame preceding the one that
has low confidence and continues tracking. This option isn’t available
if Adapt Feature On Every Frame is selected in the Motion Tracker Options
dialog box; enabling feature adaptiveness causes After Effects to adapt
the feature region with every frame regardless of the confidence
level.
- Options
- Opens the Tracker Plug-in Options dialog box, which includes
options for the AE Original Built-in Tracker. This command is only
available if you choose to use the older After Effects tracker plug-in.
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