Adobe 12040118 Tutorial - Page 219

Apply Sends the tracking data (in the form of keyframes) to the target layer or effect control point. 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. Note: To show or hide motion paths in the Layer panel, select or deselect the Display Motion Paths option in the panel menu of the Tracker panel. (The panel menu is the menu that you access by clicking the icon in the upper-right corner of a panel.) You can also use commands in this menu to add a new track point, reveal the current track in the Timeline panel, and toggle whether the feature region magnification is enabled. Motion tracking properties in the Timeline panel Each time you click Track Motion or Stabilize Motion in the Tracker panel (or choose Animation > Track Motion or Animation > Stabilize Motion), a new tracker is created for the layer in the Timeline panel. Each tracker contains track points, which are property groups that store the tracking data after tracking has been performed. Trackers are grouped in the Motion Trackers property group for each layer in the Timeline panel. To show a tracker in the Timeline panel, select the tracker from the Current Track menu in the Tracker panel and press SS. You can rename trackers and track points and modify and animate their property values in the Timeline panel just as you do for other layer properties and property groups. You must click Apply in the Tracker panel to apply the property changes to the target. Feature Center Position of the center of the feature region. Feature Size Width and height of the feature region.