Occluding using a new layer versus occluding in a single layer

Hello! After watching several Mocha AE tutorial videos I was left confused as how to properly mask for occlusions or things that you don’t want the “main” layer to track.

I saw two methods used; one was in a single layer and then using the “Add” spline tool to draw a new hole in the main mask, as visible with the Show Layer Mattes tool.

Another video (I think the cab one) showed multiple layers, where the topmost layer was tracked and then that was used as an occlusion to ignore in the layer below.

What are the differences? I got different results from some test footage of my own. Am I supposed to Link to Track?

Thanks for your questions! Both methods actually works, it’s just depends more on the type of the shot, what method to prefer.

The first one fits better when you trying to track something like a phone screen, and you have an annoying reflection at one of the corners of the screen. Or if there’s some animation or video playing on the screen, then you should track only the “frame” of the phone, but not the actual screen. So for that scenarios, “making a hole” in the layer works best.

But lets take another case. Lets say you want to track a wall, and there’s a person walking left to right in front of it. Then it’s better to separate the person by drawing a shape on second layer. Mask for the person shouldn’t be very precise, just a simple garbage mask would work fine.

The more you’ll practice in Mocha, the more you will get the feel what
method to prefer in each case.

Hope that makes sense!

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