There should be at least one surface to fill - error

I don’t know

why I am getting this error.
I tracked to the left side and the right side of the mic I wish to remove.
I tracked the mic and put that on the top layer.
I created a clean plate to use.
I get the render tool, but when I go to render, I get the “There should be at least one surface to fill” error.
Screenshot attached.

What am I missing here?
Using Mocha Pro 2019.5 V6.1.1 On Avid MC 8…1.1

Thank you, Ed

The background shape has to cover where the foreground shape is removing from. Make the BG shape encompass the FG shape and you should be all set.

Let me know!

Thank you! Works nicely.
One further question: The subject moves his hands over the mic frequently. How do I roto the hands and keep the mic hidden in the BG.

Please see attached screen shot.

Thanks again,

Hi Ed,

You’ll need to draw shapes around the fingers, track them, and correct the shape where it moves off the finger edges. The magnetic spline tool can help with this, so can using alt/option S to snap shape edges. Since they’re probably not bending much, you can probably get away with rotoscoping one finger at a time. If they’re bending a lot, you’ll need to split the shapes up at the joints of the fingers. It will be tedious to roto. You might get better results doing a remove in that section that removes the fingers and the mic together and making a new track in Avid, putting a new instance of Mocha on that, and rotoing the fingers with motion blur on that layer. You can apply motion blur in edge properties.

You can track and roto fingers at the same time, but make sure you don’t use perspective when rotoscoping.

Try that and let me know if it fixes this for you.


OK, I see how that will work. I will probably need to use roto seperately in some cases where there is a lot of hand movement on this guy.

One other question: Is there a way when I need more than one clean plate to tell Mocha when to stop using one of the plates.
Reason being that when the guy moves a lot, I need a couple of clean plates, but then they blend together where I really only want one of the plates to be used.

Thanks again for your able assistance.

No, they animate linearly. So make a new cleanplate where you want the new one to take over.

The two clean plates I am using seem to be blending in the middle of the shot. Like they are dissolving between one cleanplate and the other

That’s expected behavior. You might need a new cleanplate at that point.

Great. Thanks. I think I’ve got the concept working now.