Tracker
Function
This tool is only for generating tracks. Unlike MatchMove
and Stabilize, it will not
alter the input image at all. It is used to create tracks to be referenced elsewhere,
either in other tracking nodes, or in non-tracking nodes like Move2D,
Rotate, etc. While MatchMove and Stabilize are limited
to creating one, two, or four track points, a Tracker can hold as many
trackers as the user wants by using the Add Tracker button
at the bottom of the Parameter View. If your workflow continually
uses Smoothing and Averaging of tracks to be applied in a Stabilize or
MatchMove, you should probably generate them with a Tracker node.
The user can also delete trackers, and save the tracks to disk with Tracker, although any individual track can be saved in any of the tracking nodes by choosing from the right mouse menu when clicking on a trackName.
For general information on the three tracking functions, including button descriptions and workflow issues, jump to About Tracking.
For a tutorial on tracking, jump to Tracking Tutorial.
Parameters
|
Type
|
Default | Notes | ||||||||||
subPixelResolution | string | 1/16 |
The resolution of your track. The smaller the number, the more precise and slower your tracking will become. Possible values:
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matchSpace | string | luminance | The pixels are
matched according to the correlation between the selected color space, either
luminance, hue, or saturation. If an image has roughly
the same luminance, but contrasting hues, the user would switch over to
hue-based tracking. |
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referenceTolerance | float | .75 | A tracking correlation
of 1 is a perfect score, meaning there is an exact match between the original
reference frame and the sampled area. By lowering the referenceTolerance,
you are accepting greater inaccuracy in your track. If tracked keys are
between the referenceTolerance and the failureTolerance, they
will be highlighted in the Viewer. Also, in some cases, referenceBehavior
will be triggered if the tracking correlation is below the referenceTolerance.
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referenceBehavior | string | use start frame |
This behavior dictates what source sample a tracking area should reference.
By default, the reference sample is the first frame at which you started
the track, not necessarily the first frame of the trackRange. The
last two behaviors measure the tracking correlation and match it to the
referenceTolerance to decide an action. update every frame |
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failureTolerance | float | .5 | If the correlation
of a track falls below this value, it will initiate the failureBehavior. |
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failureBehavior | string | stop |
stop predict location and create key. don't predict location use existing key to predict location |
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limitProcessing | int | 1 | This will create
a DOD of the bounding box of all active trackers. Only that portion of the
image will be loaded from disk, therefore your tracking will go more quickly. |
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trackRange |
string
|
1 | This
is the potential frame range limit of your tracking. If you read in a clip,
the range will be set to the clip range. For generated elements like RGrad,
it will take a range of 1. You can set new limits using Shake's standard
range description, i.e., 10-30x2. If you stop tracking and start up again,
it will start from the current frame until it reaches the lower or upper
limit of your trackRange, depending on if you are tracking forwards
or backwards. |
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trackNName | string | trackN | The name of the
track. You can change this. |
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trackNX/Y | float |
width/3, height/3
2*width/3, height/3 2*width/3, 2*height/3 width/3, 2*height/3 |
The actual track point in X and Y. This is what you would use if you were linking a parameter to a track point. | ||||||||||
trackNCorrelation | float | NA | The correlation value of that key to the original sample. A score of 1 is a perfect score. 0 is a very very very very bad score. | ||||||||||
trackNWindow Parameters | float | NA | These multiple
parameters control the windowing of the tracking box, and are not relevant
to exported values. |
Synopsis
image Tracker( image In, const char * trackRange, const char * subPixelRes, const char * matchSpace, float referenceTolerance, const char * referenceBehavior, float failureTolerance, const char * failureBehavior, int limitProcessing, float referencFrame ... );
Script
image = Tracker( In, "trackRange", "subPixelRes", "matchSpace", float referenceTolerance, "referenceBehavior", float failureTolerance, "failureBehavior", int limitProcessing, float referencFrame ... );