Difficult track with jitter and motion blur

Hey!

I’m a new mocha user and need to track part of an antler to be able to replace with a painted version. The problem is that I can’t get the track to stick for very long. I have spent a lot of hours manual tracking a great portion of the shot but since there is a lot of motion blur and some fast and jerky movement the track still jitter for a big portion of the shot. I have tried What would be the best approach to tackle this task?

I have tried various settings on the tracks tab but with limited success. The main problem is that I can’t identify why the track fails at certain times and I don’t fully understand when to use the different track settings. On that subject, why wouldn’t you always want to raise the search area setting? Are there any downsides to high settings for search area and/or angle and zoom values ​​other than a slower track?

I can’t share the whole shot but here is some screenshots.

I’m using mocha pro plug-in 2022.5 in Nuke.

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With these kinds of shots it is usually better to track one consistent area and then link the roto shapes to that track.

However, it’s difficult because your antler is going to be turning and they generally aren’t planar objects.

You could for example just track the core area in the middle covered by snow, where the forking of the various prongs accumulates. You may also need to just track in translation to get the overall movement.

Increasing the search area does indeed slow things down, but if you’re fine with that you can make it as wide as you like. It should be any larger than the frame dimensions because there’s no point in going higher.

But the search range may not be enough for a shot like this (without seeing the full clip it’s hard to tell).

Mocha’s tracker has to find similar or almost similar patterns to match. If those patterns are completely obscured by heavy motion blur or have altered significantly because the object has turned in space too far, it’s going to be harder to find.

We can make more recommendations with a larger sample of the clip. If you want to send it privately we can review it.

Thanks Martin, great tips that really helped me understand how Mocha operates. I’ll try adjusting the search area to see if that will enhance the track. Even with manual track it’s difficult to get the patch to stick perfectly, simply because it’s impossible to see where the “corners” supposed to be due to heavy MB. But with a simple transform I Nuke I think I will be able to adjust those parts.

If I only track translation for a portion of the shot and then afterwards want to go back and adjust only rotation, scale or sheer for example, is that possible to do without messing with the tracking data for translation?

Is my understanding correct that you can’t really never actually keyframe the surface? If you do manual track and then adjust the surface it’s just to create tracking data, not setting keyframes for the surface.

Yes and no. If you stay in manual track mode, the surface is directly linked to the tracking data and any movement of the surface is keyframed to the tracking data.
If you switch back the Large Motion mode, the surface is unlinked again, but the manual changes to the tracking data are kept.

That’s great, thanks alot Martin!