Continuous fence tracking through shot

hi guys,

I’ve got a shot and need to roto along the fence line to remove the background.

The problem is that Mocha does too much of a good job and locks to the fence all the way through the shot pulling the spline out of frame. What I want is for the roto shape to lock to the shot but just move vertically as the fence moves up and down.

Just wondering if anyone has some tips? Any help would be greatly appreciated and save a hug amount of time as the shot 1’30" in duration!


Your best bet is to track from the end of the shot to the beginning and use overlapping shapes to get a long line of perfect roto shapes. You can’t really lock the shape off in your interface without disconnecting it to the tracking data.

You could try to delete custom keyframes in the dopesheet, but that’s more trouble than it is worth. Overlapping roto shapes will get you what you need,

Just to clarify what Mary is saying. Put a shape over a section of the fence and choose “None” next to Link to Track under the Properties section. Then make a shape (or several) for the fence and link that to the first shape that doesn’t move. The first time I used this function it seemed like it couldn’t possibly work but it does - and very well.


So, I am actually not saying to use unlink track by setting the shape to none, I am saying to use overlapping shapes. However. He could use unlinking (link to None) to get the initial track and then link shapes to that once the track is complete and finish his roto, but he doesn’t want to use unlinked tracking and then put shapes on top of his unlinked shape or he will hold that data out from them. It’s better to either track and roto several overlapping shapes through the timeline OR do an initial long track and link shapes to that. However, because this shot is so long, you will actually get better results with overlapping shapes instead of one long track.