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Converting the 3D Auto Tracking Results
Action: 3D Camera Tracking
Basic Manual 3D Tracking
Manual 3D Tracking
Before
you start manual 3D tracking, you should examine the clip closely
to determine the points you want to track. The quality of the 2D
track has a direct impact on the 3D tracking result, so it is important
that you have a strategy for positioning the trackers in the clip
sequence. Use the Stabilizer to track and stabilize the clip as
accurately as possible. See
Tracking and Stabilizing.
For optimum results,
each frame in the clip you are tracking must contain at least six
track points. In the Stabilizer, this means six trackers are enabled.
Also, at least two frames in the clip sequence must have a minimum of
eight trackers, and these two reference frames should show the widest camera
movement.
When tracking, the more
track points you have in each frame, the smoother and more accurate
the tracking result will be. As you place the trackers on the image,
consider the following guidelines:
- Scatter the trackers by placing them
on markings, corners, and shadows in the widest area possible. For
example, avoid placing all trackers on the floor; place them on
walls and other objects in the scene, as well as on the floor.
- Create a sense of depth by positioning
trackers on points that lie in different planes, as well as on points
located in the foreground and the background of the sequence.
- Avoid tracking points such as highlights
or a point where the foreground and a background object meet, as
they do not represent physical 3D points.
- Balance the number of trackers within
each frame of the sequence so that as you move through the clip,
some points leave the frame and other points appear in the frame.
However, maintain a balance so that too many points do not leave
or enter the frame at the same time.
- Avoid positioning the trackers in uniform
areas or on linear edges where the track points may slide along
the edge.
To set up manual trackers:
- In Action, click 3D Track.
- From the 3D Tracker Option box, select
Manual.
- Click Stabilizer to open the Stabilizer
menu.
- Add trackers to the scene by clicking
Add Tracker.
NoteYou can track points
only on the back clip that you load in Action.
- Drag each tracker to a position on the
image following the guidelines described in
Basic Manual 3D Tracking.
You should have at least
six trackers active at any one time, and at least two frames should
have eight active trackers.
- In the Stabilizer menu, click Analyse
to process the 2D tracking path and check your result.
If the tracking is not
correct, try standard tracking techniques as described in
Tracking and Stabilizing.
- Click Return to return to the 3D tracking
controls.
When you track a pattern
that appears to drift or stray, you should set more intermediate
trackers in the frames of the sequence, and ensure both the first
and the last reference frames are set properly.