C_Tracker Tab

Tracks

When enabled, the associated track anchor in the Viewer is used to track a feature from the input.

Sets the track name.

Adjusts the x coordinates of the associated track anchor’s center.

Adjusts the y coordinates of the associated track anchor’s center.

Sets the offset amount, in pixels, between the tracking anchor and the feature position on the x and y axes.

This is especially useful when the feature you want to track is obscured or otherwise unavailable, enabling you to track another pattern to produce the required tracking data.

Displays the longitudinal, or horizontal, position of the tracking anchor.

Displays the latitudinal, or vertical, position of the tracking anchor.

Displays the field of view used to convert from spherical to rectilinear and back again after tracking.

When enabled, pan is calculated during tracking.

When enabled, tilt is calculated during tracking.

When enabled, roll is calculated during tracking.

Note:  Tracking roll requires at least two tracks.

Displays the overall track error rating.

Click to add a new track and anchor to the Viewer.

Click to delete all selected tracks.

Click to select all tracks in the Tracks list.

Click to average all selected tracks together into a single new track. This can be especially useful for stabilization tracking.

Export

Sets the nodes to output when you click Create:

• C_SphericalTransform (Stabilise) - creates an expression linked C_SphericalTransform containing Pan, Tilt, and Roll data to stabilize the output.

• C_SphericalTransform (Match-move) - creates an expression linked C_SphericalTransform containing Pan, Tilt, and Roll data to match-move content.

• C_MetaDataTransform (Stabilise) - creates an expression linked C_MetaDataTransform containing Pan, Tilt, and Roll data to stabilize the output.

• C_MetaDataTransform (Match-move) - creates an expression linked C_MetaDataTransform containing Pan, Tilt, and Roll data to match-move content.

Click to create the export specified in export dropdown.

General

Tracking only occurs in these channels.

If you set this to something other than all or none, you can use the checkboxes on the right to select individual channels.

Sets the filter applied before image patches are compared:

• none - no filter is applied.

• adjust contrast - the default filter, stretches the image contrast to better suit the tracking algorithm. This is the recommended setting and shouldn’t need changing in most circumstances.

• median - attempts to remove image noise.

When enabled, C_Tracker does some extra pre-filtering to compensate for changes in brightness.

This option slows the tracking process and can reduce the accuracy of tracks, so only enable this control if there are known changes in brightness.

Note:  Enabling adjust for luminance changes can occasionally produce better tracks on shots with no differences in luminance, particularly on jittery shots where sub-pixel accuracy is vitally important.

Sets the maximum number of iterations before the tracking algorithm stops searching for features.

Note:  This setting does not normally need adjusting.

Sets the error level at which C_Tracker is assumed to have found the feature - no further search for a better match is performed. Higher values may result in a faster but less accurate track.

Note:  This setting does not normally need adjusting.

Sets the error level at which C_Tracker stops searching for features.

When enabled, tracked patches are clamped to values between 0-1.

Note:  If you want to track using the full dynamic range available in your footage, disable this control and adjust the max-error value accordingly. For example, images with pixel intensity 40 may require a max-error value of 40.

When enabled, keyframes on the track are colored according to their relative error:

• green - a good match for the grabbed pattern.

• amber - a reasonable match for the grabbed pattern.

• red - a poor match for the grabbed pattern.

High track error values aren’t necessarily bad keyframes. Rather, they indicate that the pattern has changed considerably since the previous pattern grab.

When enabled, the track progress dialog doesn’t display during tracking.

When enabled, adding tracks places a guide on suitable marker patterns, such as dots or blobs, in the Viewer. Move the tracking anchor to a guide and release the mouse to snap the anchor to the guide’s position.

Sets when the zoom window is visible in the Viewer:

• always - the zoom window is always visible.

• on track change - only display the zoom window when a track changes.

• when tracking - only display the zoom window during tracking.

• when tracking or track change - only display the zoom window during tracking or when a track changes.

• never - the zoom window is never displayed.

Sets the size of the zoom window.

Sets the magnification in the zoom window.

Sets when filtering is applied to the zoom window:

• always

• on playback

• never

Note:  The filter applied is the same as that selected on the Transform tab, and can produce a more visually stable track. It can make track positioning more difficult, however.

Auto-Tracking

When enabled, use the current tracker animation path to determine where to look in the next frame.

Note:  If Tracker fails to find the feature in the next frame, click the clearfwd button above the Viewer before continuing, or the same error is repeated.

Selects the transformations that are tried on the pattern to match it to the image. Translate is fastest, but may lose the track if the pattern rotates, scales, or shears over the course of the track:

• Translate - only expect pattern translation.

• Translate/Rotate - expect pattern translation and rotation.

• Translate/Scale - expect pattern translation and scaling.

• Translate/Rotate/Scale - expect pattern translation, rotation, and scaling.

• Affine - expect straight lines and the distance between the points on them to remain equal.

Note:  This control does not relate to how the image is transformed as an output, but what transforms the pattern matching algorithm utilizes to find the best pattern match.

Sets when the tracker attempts to grab a new pattern:

• on first frame - grab a pattern on the first frame only.

• every frame - grab a new pattern on every frame.

• every n frames - use the every n frames control to specify the frame interval.

• if error above - use the when error > control to specify the grab behavior.

• if error below - use the when error < control to specify the grab behavior.

• custom - use the every n frames and when error <> controls to specify grab behavior.

When pattern grab behavior is set to update every n frames or custom, sets the interval at which Tracker automatically re-grabs a pattern.

When pattern grab behavior is set to update if above tolerance or custom, sets the error level above which Tracker automatically re-grabs a pattern.

When pattern grab behavior is set to update if below tolerance or custom, sets the error level below which Tracker automatically re-grabs a pattern.

When enabled, C_Tracker re-grabs a pattern at the current position each time tracking is stopped.

When enabled, C_Tracker re-grabs a pattern when a track is manually adjusted.

Displays the GPU used for rendering when Use GPU if available is enabled. Local GPU displays Not available when:

• Use CPU is selected as the GPU device in the Preferences.

• no suitable GPU was found on your system.

• it was not possible to create a context for processing on the selected GPU, such as when there is not enough free memory available on the GPU.

You can select a different GPU device, if available, by navigating to the Preferences and selecting an alternative from the GPU Device dropdown.

Note:  Selecting a different GPU requires you to restart Nuke before the change takes effect.

When enabled, rendering occurs on the Local GPU specified, if available, rather than the CPU.

Note:  Enabling this option with no local GPU allows the script to run on the GPU whenever the script is opened on a machine that does have a GPU available.
You should also select this if you wish to render from the command line with the --gpu option.

See Windows, Mac OS X and macOS, or Linux for more information on the GPUs Nuke supports.

Sets the type of transform to apply.

Note:  The transform control must be set to none when calculating tracks.

• none - no transformation is applied to the input image.

• stabilize - transforms the image so that the tracked points do not move.

• match-move - transforms another image so that it moves to match the tracked points.

When transform is set to stabilize or match-move, sets the frame in the input sequence to use as the reference or identity frame.

Click to set the current frame as the reference or identity frame.