Basic tracking question

Compositing
1

Hi
I am trying to do some simple tracking and Combustion is messing with my head
I have a 27 second sequence of video I am trying to lock a photoshop layer to. I'm using the default tracking options applied to the PSD layer (using position, rotation and scale) and the two trackers lock to reference points beautifully. The problem ios, at various points in my video, people walk in front of camera and obscure the points I am tracking (or even the entire clicp) sometimes for a couple of seconds.
I an trying to use the techniques in the manual of tracking up to the point of obscuration, moving to a new position where the tracking points are visible again and repositioning the trackers and trying again, BUT, repositioning the trackers then screws up the good track I've already done. Some really odd things are happening, i.e. the magnifier that appears when moving the trackers is not showing whats directly under the trackers and so on. So I guess I am just asking for an idea of the correct workflow. For example, should Animate be on or off? should I deselect the trackers before moving to the new part of the footage to continue tracking? How do I ensure that when I move the trackers in the new section of the footage back to the same points I used earlier that my PSD layer will also move into the correct position?
Any guru advice greatly appreciated.

Lucas Young

2

HI,

Try putting the tolerance level to zero when the trackers become obscured. It should ignore the image when making the calculations. In cases where you have tracking data that is off the mark, you can delete the keyframes and allow the inbetween keyframes to compensate.
When all else fails, there's such a thing called manual tracking...we all have to do that at some point in our lives :wink:

jude

3

Thanks Jude
I found most of the problems were due to C* quirks - once you finish tracking a section, not only do you have to click the "Off" button to apply the data to the item you're tracking, you also have to select "None" from the background footage dropdown above the Off button. And when you then move to another part of the timeline to track again, you have to click somewhere in the preview window after you have created the trackers (with the position, scale and rotation buttons) for the two trackers to reset to the proper position (they start off way outside the preview area)

cheers