Maya Arnold Transmission Weight not working

[Gilbert159]

I've used maya Arnold a lot and created glass/plastic materials before. So I know this is a weird one.

Usually I just forget to turn up my Transmission Rays which is why I get black. But not this time.

When I turn the Weight up to 1 I get basically solid black. But when I turn it to around .9 I kind of get transparent . And 0 is just it's base solid colour which is white.

What's going on here?

Everything's got Opaque turned off.

[Gilbert159]

So I gave the scene a ground/backdrop and it looks correct. So it not the material. It's just picking up the environment. But when I change the background colour within the renderer, it doesn't pick it up... the background changes but the reflections don't.

Why is it not picking it up as transparent aka with Alpha? I don't want a background because I just want to light it and change the background in post. How do I get around this???

[Gilbert159 · Accepted solution]

Answered my own question lol. Found the answer here:

https://docs.arnoldrenderer.com/display/A5KTN/Transmission+and+Opacity

If using a Skydome, Turn Transmission to 0. Otherwise just turn on Transmit AOV's.

It's always something simple smh