Surface goes all crazy when doing manual tracking

I’ve got some screen comp tracks I’m doing, where some of the frames are to off-axis or hectic to track, so I have to manually track those frames.

Sometimes it works fine, but sometimes, after manually tracking for a few frames, the surface ends up going completely crazy and distorted, and it propagates throughout all the previous keyframes that were fine. My only option is to undo back to before it got all warped, but often times, once I’ve hit the frame where it wants to go crazy, I can’t track anymore and have to create a whole new shape and just track to blend between the two shapes in After Effects.

Or, sometimes I can’t even undo, because when I do, now the surface is offset in some way, and it has propagated throughout all the rest of my keyframes as well, so I have to start over from scratch.

I’m curious what is happening to make it go crazy, and why it only happens sometimes.

If you using perspective when you track, it may be that your surface is going behind the camera in mocha and corrupting the data. In mocha, problem splines can occur when the tracking data has become so skewed it goes off or “behind” camera, the keyframes the tracking data generates can throw the shape information out of order. You may need to re-track the shape using only translation, scale, rotation, and shear instead of perspective. This is especially true for complex roto of an object that is turning away from screen or tracking an object that is turning.

Please let me know if you have any questions and I will be happy to help you.

Ya the track doesn’t involve perspective tracking.

The other thing that’s weird is that on the frames it wants to mess up, it’s not like it’s on a drastic change in perspective. It seems like it just lets me manually track a certain number of frames, and then will just wig out.

Weird, can you send me the shot?