Tracking an Object With Drastic Size Change

I am tracking a complex object that requires about 25 nodes for the spline to be accurate. The object then gets quite small for a long while. 25 nodes is way too many. What is the best way to handle this - erase many of the nodes in the original spline? Create a new spline with fewer nodes?

Thanks.

It’s very likely you don’t need that many, try a square around the most obvious plane within the object and try again. That will probably work for you.

Please let me know and I will be happy to continue to help you.

Cheers,
Mary

I’m tracking the changing object in part to remove the object (creating a matte), so I need to accurately trace the outer edges of the object.

Thanks.

But you can track the object with a simple shape first and attach roto after with link to track. Also, you should not be using complex masks for the Remove module, you want loose garbage mattes. If you use too tight of a mask you’ll leave pixels from the object you are rotoscoping on the background and they will get populated through the remove.

Cheers,
Mary

I’m still not sure how to remove an object without using splines that trace the object in time. The object changes shape.

Right. I am saying you don’t have to trace it so closely, draw a looser circle or square around it. Track translation only if you have to. The track on the FG object you are trying to remove isn’t the important part of the remove.

You can send me a picture and I can help you further, as right now I can only speak to generalizations. Maybe you have a really complex shot?

Let me know and I will be happy to help you.

Cheers,
Mary

It seems someone the other day asked a similar question. Is it possible to break up a track by using a unique tracking spline for various layers, then combine them in exporting tracking data? A brief attempt didn’t seem to work. I tried linking each layer to the first layer but it seemed to fail.

Thanks.

So, all overlapping mattes can be exported to any host, that’s not an issue, you can make several mattes all linked to the same base track using Link to Track in the layer properties menu. You can also export them all as a single black and white matte for a host we don’t support spline exports for.

If linking tracks are failing, it is that the track itself needs more work. Try doing a basic track with a simple shape and then linking these more complex shapes to that. If you run into difficult areas to track, use translation, scale, and rotation only, sometimes even using only translation is the best option, depending on how the shot is moving.

However, since Mocha is a planar tracker, if you’re tracking multiple planes of movement at once, like a whole person instead of a person in “paper doll” style roto, you will very likely not have a good initial track to work with or link shapes to.

Have you checked out our “Getting Started with Mocha” training series by Ben Brownlee? It’s extremely helpful for becoming at ease with Mocha’s workflow. Boris FX | Videos

Cheers,
Mary

Will check out those videos, tho I think I’ve seen them all. Thanks.

The matte creation parts works fine. For tracking tho, I just have times when a simple tracking of the object can be done with, say, 8 node splines, then it gets really complex so I wanted to track using some more nodes for those sections. Tracking with the simple splines all the way doesn’t give a good result.

So for this 1 object that changes shape I thought I could have 2 tracking layers, 1 where simple shapes can be accurately tracked using a simple spline, then on other sections where it requires many more nodes to get an accurate track I could use a separate spline.

I tried linking to Track 1, which has the simple spline, but the data seems to get lost maybe?

Anyway, will check out the videos and keep tinkering.

I tried all the various tracking possibilities, lie shear, perspective, etc.

Thanks.

In those cases, try add to xspline instead. Or simply edit the shape points as you go. Since it’s the track layer, that doesn’t matter much. Use another layer for the roto matte.