rendering alpha channel only

[jtvfx]

Hi all,

I just have a perhaps very simple question, I just couldn't figure out how to do it...

How do I render out alpha channel only? I want to only render out the alpha because I already have the RGB channel, and I don't want to render it out with alpha all over again.....

Hope someone here can help me out with this!

Thanks!!

[jkunz07]

Hi all,

I just have a perhaps very simple question, I just couldn't figure out how to do it...

How do I render out alpha channel only? I want to only render out the alpha because I already have the RGB channel, and I don't want to render it out with alpha all over again.....

Hope someone here can help me out with this!

Thanks!!

I think the easiest thing to do would be to use the constant shader or a global material (matte) override. I don't think there's a way to only render the alpha channel, you could make a custom shader putting alpha values into the rgb channels but it would still be an {r g b a} image and not just {a}. I don't think it would be any quicker than using a constant shader or material override either.

[jtvfx]

I think the easiest thing to do would be to use the constant shader or a global material (matte) override. I don't think there's a way to only render the alpha channel, you could make a custom shader putting alpha values into the rgb channels but it would still be an {r g b a} image and not just {a}. I don't think it would be any quicker than using a constant shader or material override either.

Thanks!! I will give it a try!