Billboard question- Solved

Serene Night

Okay I really like the billboard product but want to make my own billboards. What I'm stumped by is what qualities the renders should have.

1 render is the character rendered as png saved on transparent background added to diffuse.

2nd render is character silohuette all white with black background  which is supposed to mask and hide the square around the first character. It too is png

i seem to be able to do the first image but the second image properties although straight forward looking seem to mask the whole billboard rather than to just punch out the borders. What qualities is this second render supposed to have that I'm missing?

oh I am just pasting these images into the same channels as a premade one so haven't altered other settings in the billboard beyond that.

i appreciate the help.

 

Serene Night

I solved this question. the missing piece was that the image in the opacity channel needed to be grayscale. Done!