User Manual

After you’ve drawn a pattern, a set of Pattern parameters lets you transform and invert the
resulting polygon, if necessary.
Track Mode
Track mode is unlike the other three options in the Operation menu in that is the only option
that initiates the planar tracking. The other modes use the tracking data generated by the
Track mode.
Tracker
There are two available trackers to pick from:
 Point: Tracks points from frame to frame. Internally, this tracker does not actually track
points-per-se but rather small patterns like Fusion’s Tracker node. The point tracker
possesses the ability to automatically create its internal occlusion mask to detect and
reject outlier tracks that do not belong to the dominant motion. Tracks are colored
green or red in the viewer, depending on whether the point tracker thinks they belong
to the dominant motion or they have been rejected. The user can optionally supply an
external occlusion mask to further guide the Point tracker.
 Hybrid Point/Area: Uses an Area tracker to track all the pixels in the pattern. Unlike the
Point tracker, the Area tracker does not possess the ability to automatically reject parts
of the pattern that do not belong to the dominant motion, so you must manually provide
it with an occlusion mask. Note that for performance reasons, the Hybrid tracker
internally first runs the Point tracker, which is why the point tracks can still be seen in
the viewer.
There is no best tracker. They each have their advantages and disadvantages:
–
Artist Effort (occlusion masks): The Point tracker will automatically create its internal
occlusion mask. However, with the Hybrid tracker, you need to spend more time
manually creating occlusion masks.
–
Accuracy: The Hybrid tracker is more accurate and less prone to wobble, jitter, and
drift since it tracks all the pixels in the pattern rather than a few salient feature points.
–
Speed: The Hybrid tracker is slower than the Point tracker.
In general, it is recommended to first quickly track the shot with the Point tracker and examine
the results. If the results are not good enough, then try the Hybrid tracker.
Motion Type
Determines how the Planar Tracker internally models the distortion of the planar surface being
tracked. The five distortion models are:
 Translation.
 Translation, Rotation (rigid motions).
 Translation, Rotation, Scale (takes squares to squares, scale is uniform in x and y).
 Affine includes translation, rotation, scale, skew (maps squares to parallelograms).
 Perspective (maps squares to generic quadrilaterals).
Each successive model is more general and includes all previous models as a special case.
When in doubt, choose Perspective for the initial track attempt. If the footage being tracked has
perspective distortions in it, and the Planar Tracker is forced to work with a simpler motion type,
this can end up causing the track to slide and wobble.
Chapter – 107 Tracker Nodes 2409