Alpha problem with backplate

[malindis]

Hello,

I'm on Mac with Corona 6 hot fix 1 and C4D s22.

I have a simple scene with a backplate for the sky (not for lightning the scene but only for visibility). This backplate is assigned with a light material where I put the picture of the sky. This material emits no light (Emit light to OFF) and in the advanced settings I have unchecked the Visible to alpha channel...

Now when I render the images, the backplate is still visible in my alpha !!! why is that ?

Thanks for your help.

Best

stefan

[Beanzvision]

Hi Stefan,

Can you share your scene with us via our private uploader?
https://corona-renderer.com/upload

[malindis]

Hi,
I have just uploaded the files

[Beanzvision]

Hi Malindis,

Is this what you were trying to do?

[malindis]

yes, what am I doing wrong ???

[Beanzvision]

For your clay material, I enabled "Always black" in the alpha mode.

[malindis]

OK but what do I do when I have multiple material assigned to my scene ???

[Beanzvision]

It should be working by default so it looks like there might be a bug with a light material on a plane when working with the alpha channel. Instead of the background plane, you could replace that with a Corona sky and set the projection to frontal. With a few tweaks, you should get an identical look as to that of the background plane.