The Tracking Tab

Motion tracking is the process of analyzing a shot in order to follow the motion of a specific feature in the image to create a motion path. Once you’ve done this, you can use these motion-tracked camera paths to animate secondary vignettes, Pan & Scan operations, user shapes, and the Vignette node in the Color FX room to follow these motion paths. This way, the corrections you make appear to follow moving subjects or the motion of the camera.

There are actually two kinds of tracking:

You can use either one or both of these methods together to track a subject’s motion.

Note: Color can only use one-point motion tracking. Two- and four-point tracking are not supported.

Will Motion Tracking Solve All Your Problems?

With shots where there is a clearly defined target (something high-contrast and angular, preferably), automatic motion tracking can be the fastest way to quickly and accurately animate a vignette to follow the motion of the subject or camera in a shot, but not always.

If you’re working on a shot where automatic tracking is almost usable, but has a few errors, you might be able to use manual tracking on top of the automatic track to correct the most egregious mistakes, and then increase Tracking Curve Smoothness to get an acceptable result. For more information about manual tracking, see Using the Tracking Tab.

However, if actors or other subjects in the shot pass in front of the feature you’re tracking, or if the motion of a shot is so fast that it introduces motion blur, or if there’s excessive noise, or if there’s simply not a feature on the subject you need to track that’s well-enough defined, you may need to resort to manual tracking for the entire shot, which can be tedious if it’s a long shot. In many cases, manual keyframing may well be the most efficient solution. For more information on keyframing, see Keyframing.

Using Motion Tracking to Animate Vignettes and Shapes

After you’ve processed a tracker, you can use that tracker’s analysis to animate the following:

  • A vignette in the Secondaries room

  • A user shape in the Geometry room

  • X and Y positions in the Pan & Scan tab of the Geometry room

  • The Vignette node in the Color FX room

When applied to a vignette or a user shape, the animation of the Motion Tracker is added to the X and Y positioning of the shape. For this reason, it’s most efficient to track a subject and assign that tracker to the vignette, shape, or setting first, and adjust the positioning later.

For example, suppose you’ve used a tracker to follow the movement of someone’s eye, and you want to apply that motion to a vignette that highlights that person’s face. You should choose the tracker from the Use Tracker pop-up menu first. As soon as you choose a tracker, the vignette or shape you’re animating moves so that it’s centered on the tracked feature. At that point, you can position the center, angle, and softness of the shape to better fit the person’s face. This way, the vignette starts out in the correct position and goes on to follow the path created by the tracker. Because the tracker uses an additional transformation, you can still reposition the vignette using the X and Y center parameters or the onscreen control in the Previews tab.

If you track a limited range of a shot’s total duration by setting In and Out points for the tracker that are shorter than the length of the shot, the vignette stays at the initial position you drag it to until the playhead reaches the tracker’s In point, at which time the vignette begins to follow the tracker’s motion path. When the playhead reaches the Out point, the vignette stops and remains at the last tracked frame’s position until the end of the shot.

Note: If you apply a tracker to the Pan & Scan settings for any shot in a project that was sent from Final Cut Pro, the tracking data will be lost when the project is sent back to Final Cut Pro. However, if it’s for a project that’s being rendered as a DPX or Cineon image sequence, the animated Pan & Scan settings will be rendered into the final image.

Controls in the Tracking Tab

Motion tracking is accomplished by creating a tracker in the Tracker list in the Tracking tab of the Geometry room. You can create as many trackers for a shot as you like, but you can only use one at a time to animate a vignette or shape. The Tracker list shows every tracker you’ve created and analyzed for a given shot, and each tracker has an ID number (they’re numbered in the order in which they’re created). These ID numbers appear in the Use Tracker pop-up menu for any vignette or shape that can be animated using a tracker.

Figure. Tracker list.

The Tracking tab has the following controls:

Figure. Tracking parameters and controls.
  • Tracker list: A list of all the trackers that have been created for the shot at the current position of the playhead. This list has three columns:
    • Name column: The name of that tracker. All trackers are named in the following manner: tracker.idNumber
    • ID number: The ID number that corresponds to a particular tracker. This is the number you choose from any Use Tracker pop-up menu to pick a tracker to use to animate that adjustment.
    • Status column: A progress bar that shows whether or not a tracker has been processed. Red means that a tracker is unprocessed, while green means processed.
  • Manual Tracker: Click to enter Manual Tracking mode, where you use the pointer to click on a feature in the preview area that you want to track. Each click positions the onscreen tracker control manually to create a tracking keyframe, and then advances the playhead one frame, until you reach the end of the shot. Using this feature, you can rapidly hand-track features in shots that automatic tracking can’t resolve.
  • Tracking Curve Smoothness: Smooths the tracking data to eliminate uneven or irregular motion. Higher values smooth the tracked motion path more. You can smooth both automatic and manual tracking data.

    Note: The original Motion Tracker data is retained and never modified via the smoothing.

  • Process: Once you’ve adjusted the onscreen controls to identify a reference pattern and search area, click Process to perform the analysis.
  • New: Creates a new tracker in the Tracker list.
  • Remove: Deletes the currently selected tracker in the Tracker list.
  • Mark In: Marks an In point in the current shot at which to begin processing. When you create a new tracker, the In point is automatically created at the current position of the playhead.
  • Mark Out: Marks an Out point in the current shot at which to end processing. When you create a new tracker, the Out point is automatically created at the end of the last frame of the shot.

Using the Tracking Tab

This section describes how to use the Tracking tab to create motion paths with which to animate vignettes, shapes, and Pan & Scan settings.

To automatically track a feature
  1. Move the playhead to the shot you want to track.

    Since a new In point will be created at the position of the playhead, make sure to move it to the first frame of the range you want to track.

  2. Open the Tracker tab in the Geometry room, then click New.

    A new, unprocessed tracker appears in the Tracker list, and its onscreen controls appear in the image preview area. A green In point automatically appears at the playhead in a new track of the Timeline, and a green Out point appears at the end.

    Figure. Tracker in point in the Timeline.

    In many cases, the In and Out points will include the whole shot. However, if the feature you’re tracking is not visible or only moves for a small portion of the shot, you may want to set In and Out points only for that section of the clip. If the In point was incorrectly placed, you can always move the playhead to the correct frame and click Mark In.

  3. Drag anywhere within the center box of the onscreen control to move it so that the crosshairs are centered on the feature you want to track.

    In this example, the Reference Pattern box is being centered on the man’s eye.

  4. Adjust the handles of the inner box (the Reference Pattern box) to fit snugly around this feature.

    Figure. Moving a tracker and adjusting its reference pattern.

    The bigger the box, the longer the track will take.

  5. Next, adjust the outer box to include as much of the surrounding shot as you judge necessary to analyze the shot.

    Figure. Adjusting a tracker's search area.

    Tip: For a successful track, the feature you’ve identified using the Reference Pattern box should never move outside the search region you’ve defined as the shot proceeds from one frame to the next. If the motion in the shot is fast, you’ll want to make the outer box larger, even though this increases the length of time required for the analysis. If the motion in the shot is slow, you can shrink the Search Region box to a smaller size to decrease the time needed for analysis.

  6. Move the playhead to the last frame of the range you want to track, then click Mark Out.

    A green Out point appears in the Timeline.

    Figure. Tracker Out point in the Timeline.

    In many cases, this will be the last frame of the shot. However, if the feature you’re tracking becomes obscured, you’ll want to set the Out point to the last frame where the feature is visible.

  7. Click Process.

    Color starts to analyze the shot, starting at the In point, and a green progress bar moves from the In point to the Out point to show how much of the clip has been analyzed.

    Figure. Progress bar in Tracker list.

    When processing is complete, that tracker appears with a green bar in the Status column of the Tracker list, and that tracker is ready to be used in your project. That tracker’s motion path appears in the image preview area whenever that tracker is selected.

    Figure. Motion path in image preview area for analyzed tracker.

    If necessary, the tracker is ready to be refined with smoothing, manual repositioning of individual control points in the motion path, or manual tracking. When you’re finished, the tracker is ready to be used to animate a vignette or shape.

If the resulting motion path from an Automatic Tracker has a few glitches, you can drag individual keyframes around to improve it.

To manually adjust a tracked motion path
  1. If necessary, set the Tracking Curve Smoothness to 0 so you can more accurately see and position the tracked keyframes.

  2. Drag the playhead in the Timeline through the tracked range of the shot, and identify keyframes that stick out incorrectly, or that drift from the proper direction of the subject’s motion.

  3. Drag the offending control point in the preview area so that it better fits the overall motion path.

    You can drag any control point in the motion path to a new position, not just the keyframe at the position of the playhead.

If there’s a shot in which the motion is too difficult to track automatically, you might try manually tracking the feature. You can turn on the Manual Tracker option either to correct mistakes in an automatically tracked motion path, or you can use manual tracking on its own to create an entire motion path from scratch.

To manually track a feature
  1. Move the playhead to the shot you want to track.

  2. Open the Tracker tab in the Geometry room, and do one of the following:

    • Click an existing tracker in the Tracker list to modify it.

    • Click New to create a new motion path from scratch.

  3. Click Manual Tracker to enter Manual Tracking mode.

    Figure. Manual Tracker checkbox.

    When you turn on manual tracking, the onscreen tracker control disappears.

  4. Move the playhead to the first frame of the range you want to track, then click Mark In.

  5. Now that everything’s set up, simply click a feature in the preview area that you want to track.

    For example, if you were tracking someone’s face for vignetting later on, you might click the nose. Whatever feature you choose, make sure it’s something that you can easily and clearly click on, in the same place, on every frame you need to track.

    Each click creates a keyframe manually, and then advances the playhead one frame.

    Figure. Manually placed tracking point.
  6. Click the same feature you clicked in the previous frame, as each frame advances, until you reach the Out point, or the end of the shot.

    As you add more manual tracking points, a motion path slowly builds following the trail of the feature you’re tracking.

    Figure. Motion path for manual tracker.
  7. When you’ve finished manually tracking, stop clicking.

    That tracker is ready to be assigned to a parameter elsewhere in your project.

    Note: Turning off the Manual Tracker does not turn off your manually tracked keyframes.

Sometimes a motion track is successful, but the resulting motion path is too rough to use in its original state. Often, irregular motion will expose an animated effect that you’re trying to keep invisible. These may be seen as jagged motion paths.

Figure. A tracker's jagged motion path.

In these cases, you can use the Tracking Curve Smoothness slider to smooth out the motion path that’s created by the tracker.

To smooth a track
  1. Select a tracker in the Tracker list.

  2. Adjust the Tracking Curve Smoothness slider, dragging it to the right until the motion tracking path is smooth enough for your needs.

    Figure. A tracker's motion path after smoothing.

    The Tracking Curve Smoothness slider is nondestructive. This means that the original tracking data is preserved, and you can raise or lower the smoothing that’s applied to the original data at any time if you need to make further adjustments. Lowering the Tracking Curve Smoothness to 0 restores the tracking data at its originally analyzed state.