On the factory control boards you cannot add any custom mask currently. We might add this in the future.

Currently as a workaround you can open up the VirtualCam compound and add this manually.
Choose Edit Compound In-Place:

The go to the BILLBOARDS boards, right-click KEYER 1 and choose Go To Source Module:

Insert a Masker module after the Keyer's output:

The use Masker's Mask property to select any grayscale image as a mask:

The easiest way to create a mask image is to use an external software like Photoshop, but you can also use the Paint functionality of Aximmetry if needed.

Can I get an example showing how to use Paint modules as masks 

In [Common]:Tutorials\Paint And Touch\Paint_Elements.xcomp you can find some exmples of drawing simple geometry elements.

Hello

I'm following the steps above but could'n edit the KEYER1 as you say, (The go to the BILLBOARDS boards, right-click KEYER 1 and choose Go To Source Module:)

I'm in Aximmetry Professional DE edition 2021.2.0 build 19112, when i righ click over KEYER 1 not shows  Go To Source Module

Please Help.

To edit the compound you need to first unlink it in the main node editor. 

@TwentyStudios

How i do that? Can't find the option

It’s the first step in the instructions in this thread. 

Already follow all the instructions, but when right click over Keyer 1 the  Go To Source Module Is not showing

It’s right there:

Currently as a workaround you can open up the VirtualCam compound and add this manually.

Choose Edit Compound In-Place:

The first part is ok, I open the VirtualCam compound, then, edit compunund in place, then, go to billboard, but when I right-click over Keyer 1 the  Go To Source Module Is not showing

I can verify that in the latest version of Aximmetry DE, the "Go To Source Module" option is NOT showing even after unlocking.  It used to show that option in the previous version version.  I had to manually go there as demonstrated.   There must be some process that changed to get the "Go to source module" to be an option in the latest version.

Hi all,

That's right, it is because the VirtualCam compound has been made more modular inside,  meaning Keyer is inside another linked compound now.  It's called INPUT %N=1.   You have to unlink it as well,  after that Go To will work as before.

@Zoltan: More modular so that you can add more than 3 Billboards? Would really love to have that feature soon.

Your hunch is right. ;)   But it was only the first step, other challenges still have to be solved.  Coming soon.