Motion tracking (multiple track points)
by Jens Byl on Dec 4, 2009 at 12:13:50 pm
I am trying to do the following:
I have a video with an almost 360 degrees camera rotation in it. In this scene the camera follows a pattern of imaginary lights that go on as the camera follows it (like it films a street and the lanterns go on one at a time at a specific time). The video is meant to show which ones go on at which time. I wanted to make the video dark (it's a video shot in daytime) and add real lights to it but I'm on a deadline and I now just want to put a square around the lights that go on at which time (still following?).
Now, I learned that I can motion track the camera movement and keep the squares on the lights on place as the camera moves in his almost 360 degrees rotation, but when I set a tracking point it obviously loses that tracking point at one time as the camera does it's rotation and the object is not in the scene anymore. Do you guys know how to make a smooth motion track with multiple track points without having too much jitter with the camera?
You'll have to perform Offset Tracking which is a way for the tracker to continue tracking objects that either move offscreen or to start tracking an object as it is about to come into view.
When a tracked object leaves the screen, you will have to pick another target that shares similar movements with the originally tracked object from which to continue tracking. For example, if you were to track the front of a bus and the front of the bus moves offscreen, you then perform an Offset Track by choosing the back of the bus (of course the back of the bus doesn't leave our view the).
The procedure to initiate Offset Tracking is to move the Search Region while holding down the Alt/Option key.
Below are two COW tutorials that solve Offset Tracking with differing solutions.