A little more detailed instruction

I’ve been learning Mocha and for the most part am solid with it. I’ve been working on rotoing some people (Torso, Upper Arm, Lower arm, hands. All separate roto-masks) and have had an issue.

If I adjust the Tracking X-spline during the track, when I attach my Rotospline later, it scales and moves at those adjustment points too. So I’m afraid to adjust my initial tracks and therefore cannot track certain objects well at all. The online tutorials and the Manual all make it look like you can adjust your X-spline track all you want with little/no effect on the roto. Am I missing a step or mis-interprting the lessons I’ve seen.

I thank you for the latest tracking tutorial, replacing the background posters. That is a more real life/difficult shot to solve and it helped me with corner pinning. Can you show us a difficult roto/track and explain how to adjust your track so it will have the least impact on the tighter roto-mask? Perhaps doing the roto on the man walking in front of the posters.

Thanks, Chris

This seems a little strange but your work flow is correct.

However there are many difrent ways to achieve a good roto result.


  • If you use the tracker as a kinda automatic tweener and then refine the spline as you go along you avoid the issue, of having to link your tracking layer to a new tighter spline. (PROS’s this is a great way to build up your roto quickly


  • You generate a loose spline around the object and track away then refine that spline once all your tracking is done. PRO’s its quicker and generally more effect CON’s that if you need to retrack you have to start again normally.


  • Create master keyframes of nice tight roto say every 10 frames or when there is significant change in object movement. then go back to the begining and track away. The issue here is that the spline looks like its going crazy but once all the tracking is done and you play back you actually get a really great result.

Some larger customers of ours came up with this workflow and it seems to work for them.

I hope this helps

Can you describe exactly what steps you are taking? In particular I don’t know what you mean by “…when I attach my Rotospline later”.

You should be able to adjust your X-splines all you like during the track… all you’re actually keyframing is the area Mocha should be searching in for tracking data; you never really see (or can move) the tracking data it’s self, beyond giving Mocha bad information (x-splines that encompass items not on the same plane, etc.)

Thanks for responding!
By “attach rotosplines later” I’m referring to the process of (after tracking an object with a loose X-spline) creating a new layer that has a much tighter/more articulated spline for rotoing the object. That layer is supposed to be linked (attached) to the track so it moves with the object you’re rotoing.

I’ve had problems with my track spline’s adjustments applying to my roto-spline. Let’s say as I track an object (on a dolly in), I need to pause the track and adjust the spline because the object is growng ouside the bounds of the spline (probably not an issue with Mocha, but pretend!). I now have a keyframe that scales the spline up during the track.

When I go back and make a tighter spline on a new layer, the link that layer to the track, my new roto-spline stretches (scales with the keyframed motion) with my track spline. But I don’t want it to. That tracking data should only drive position & rotation data, right? I think I’m overthinking this software from too many years of point tracking!

It’s been a few weeks since I’ve used Mocha, I hope I haven’t left out a step or detail. I will run some test tracks/roto tonight to make sure what I’ve written is accurate.

Thanks a lot for checking in.


Does anyone on the forum have any advice on this?


Thanks for the response. That third technique looks interesting. Gotta try that out. “This seems a little strange” As I said in my previous post, I will run some more tracks an make sure the facts I wrote in that post are accurate. Didn’t get a chance last night :frowning:

Thanks so much for the help.