Something wrong with the alpha channel when rendering in Maya 2018

[Anonymous]

Hi, so I have this scene. There are three separate objects: the stairs, the front wall and the side walls. There is also an AiSkyDomeLight lighting the scene. The Beauty looks okay but when I check the alpha is all wrong. The front wall and the stairs are white, that's correct, but the side walls are in black while the background is white, and should be the other way around. I'm confused. I think there is something to do with the shading but I am not sure, also I'm not sure why the bg is white.

The side walls have a Layered Shader where I have input an aiStandardSurface shader as the base color and a painted texture with transparency from photoshop on top of the base color to add the details you see. Could be this doing something wrong in the Alpha channel?

I've tried changing the Opacity, Opaque and visibility options but not working. Any ideas?

Thanks in advance.

[lee_griggs · Accepted solution]

Can you post your shader network? Are you using a native Maya Layered shader? If so, have you tried Arnolds Layer shader?

Is the skydome color white? The background will be white if the Camera Visibility is 1. Try reducing it to 0.

[Anonymous]

Hi @Lee Griggs thanks for responding, turning the visibility on camera of the skydome worked, thanks!

On the other hand, here's a screenshot of my shading network

As you can see, yes I am using the Maya Layered Shader. If I'm not mistaken, Arnold doesn't have this kind of shader. I know there's an aiMixShader that has similar options, but I already tried it and it didn't worked how I wanted, plus it doesn't have as many settings as the Maya Layered. I know I also could try to input the texture with transparency in the Coat node of the Standard Shader but that would only let me input one node, and I want to have several layers (as you can see in the screenshot). The interesting thing is that everything is working fine in the Beauty pass (well, only one issue and is that somehow when I plug the texture file in the layered shader it changes the color of it, not sure why but I actually don't mind it), it's just in the Alpha that things don't seem to be working, it is strange.

thanks for your time!

[lee_griggs]

Have you updated your plugin? A new Arnold Layer shader was introduced in 3.0.0 . I'm not sure if Maya's Layered shader is fully supported.

[Anonymous]

I see! Oh I can't find it in my Maya. My Arnold version is the 2.1.0.1, I guess I will have to update it to the 3.0. Oh well. Thanks for the tip, I will try to solve it! Thanks again @Lee Griggs