I'm use Mocha fairly regularly, but apparently there's a basic way that it works that I just can't figure out. I'm hoping someone could direct me to a tutorial that addresses my issue - I 've tired looking around, but since I don't know how to fix my problem, I'm not sure what terms to search for, and I haven't found quite what I'm looking for. I would post on the Imagineer website, but it's down for the time being.
What I want to know is how to adjust my track to get it back on point when it loses its point of reference briefly. For example, I was tracking someone's fingers recently, and at one point, they wiggle them really fast and then settle back into place. During that wiggle, Mocha lost the track point (fingertip) and latched on to something else nearby. During that wiggle, I adjusted the track pints back to where they should be, but when I export the data to AE, it's still all wrong. I thought I figured it out using the Animation button, and it's closer, but the track point still drifts off of where it should be during the wiggle, then settles back in and matched the correct motion, albeit off to the side.
Do I need to adjust key frames in the dope sheet, move the surface around, with or without the Animation key on…? I want to learn how to do this myself, I just don't know what to learn about.
Any help is appreciated. Thanks in advance.
The other thing you could do is stop the tracker when it goes off, skip to a portion that is more trackable, then continue. Also - you can turn on "manual track" to expose all tracking keyframes for manual adjustments. Beware, this can be difficult for a new user to manage, but sometimes necessary depending on the challenge.
Thanks to both of you. Neither quite solved a problem I'm having with a similar yet different shot, but it's definitely closer. I think I just need to spend some more time on it. I really do need to delve deeper into using the Manual Track feature as well.
When using the Adjust Track, it is ideal that you have a keyframing strategy. Without going at length, here's a procedure I suggest you undertake -
1) make a note of the timespan where the tracking anomaly occurs
2) in the Adjust Track Module, set a keyframe ONE FRAME BEFORE and another keyframe ONE FRAME AFTER the timespan that you noted in (1)
3) before adding more keyframes in the Adjust Track Module, look for the frame in time where the discrepancy of the tracking anomaly is the greatest. make your first adjustment on this frame.
4) move the time indicator between the first keyframe you created and the one you created in (3) - the frame with the largest discrepancy.
5) while performing (4), look for the frame with the largest discrepancy. apply the technique you used in (3) - ie adjust the tracking result on the frame with the largest discrepancy.
6) repeat the steps until you've completed the first segment. then repeat all the steps for the second part of the segment.
This may sound like a lot of work but you will very likely end up with a lot fewer keyframes than if you didn't have a keyframing strategy to work within.
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Thanks for your reply (and sorry for the delay in thanks).
I appreciate you taking the time to write this out. It's the strategy I usually use for key framing/roto, and in every application other than Mocha, it works 100% of the time. I do have trouble with the way Mocha does keyframe interpolation in the Adjust Track module though, and I'm still having a difficult time getting my head wrapped around it.
I just posted a question about this in a different thread - it's not online quite yet since I'm a new user, but if you happen to have a spare few moments, I'd appreciate it if you have a look. If not, I still appreciate your thoughts and advice.
I think I have a similar kind of problem.
Let's say that my trackpoint in mocha is drifting upwards, and then back where it needs to be - my problem is that when I adjust it in a point of time where the drift occurs the most, then it doesn't just fix the whole drift between my keyframes, but instead it creates two smaller drifts on both sides. And it keeps going, the more adjustments I make, the more smaller drifts appear - up to the point where they are to small to be noticable.
That seems totally illogical to me, since in AE when you place a keyframe it interpolates the motion between previous and next keyframe, and here it looks like the interpolation "handles" are too short to reach the neighbouring keyframes, which leaves me with a nightmare of having to adjust each trackpoint dozens of times individually.
Have you followed the steps I proposed in my last post, in this thread?
Do you have any specific questions regarding those steps?
FWIW, mocha, by default works with linear keyframes. Regardless of this, the Adjust Track works by creating keyframes that offset the original tracking data. Nothing is done directly to the original tracking data. What you get is another level of tweaking the tracking results.
AdjustTrack is a 2nd layer of keyframes that is applied as global adjust to the primary tracking.
So if your original track has major drift, or is not as good as possible, than your adjustments will fight the original track which still has animated keyframes.
My suggestion is to use various tracking techniques to get a solid track before going in and adjusting if possible. Adjust is used for tweaking small drifts, but not for complete retweaking the overall track.
Hoep that helps. The Adjust does not replace the keyframes from the original track, it simply applies secondary keys on top.
The worków you described is exactly how I do it, looks like my problem lies in the track itself, like Ross said.
My track wasn't solid at all, it drifted all the way to the side. I thought that's ok and that I should correct it in adjust track. I watched almost every tutorial about track adjusting there is, but none of them described the techniques to get a perfect track in the first place.
I guess I know what to look for now, thanks.
Hi Marcin, as you now know, always get the best track possible before using the Adjust Track Module.
BTW, the keyframing strategy I've mentioned, and which you use, will work similarly if you did the adjustment in AE. You do need a few simple Expressions to set up the workflow. The advantage in AE is that it's easier to work with the Graph Editor - this will come in handy (though not all the time) by reducing the number of manually adjusted keyframes you require.
Do you have any specific tutorials regarding this matter (how to properly correct a plane drifting to the side during track) to recommend?
I guess I'm doing something wrong - when I notice the plane starts changing shape I manually put it more or less back to the original, but when I continue the track it doesn't seem to affect the already drifted track.
There are many tutorials about planar tracking. Firstly, you need to understand the concept of planar tracking and selecting a good region to track. If there are things like reflections or foreground elements you need to avoid this with multiple layers or animating your search layer.
Other tips - increase the % of pixels in the track tab.
View the surface as you track. If it is not tracking well, your search area and what you are tracking is the issue. While mocha can solve really difficult tracks, it is not magic and the user has to feed it good information.
Hi Marcin, Ross has links to videos to help you sort out general issues. If you still have issues, then you may require specific assistance. If so, provide screencaps of mocha's tracking spline and search parameters. Then, either embed your tracking footage here or provide a link.