Material as alpha channel

[Anna1]

Hi everybody,

has anyone tried out to create an alpha channel from a material using the "Material ID" in the "Options" channel in a material? I tried lots of different things, but cannot get it to work.

It would be great, if anyone could explain me the steps. I have no idea, why it is not working.

Have a nice day and thanks a lot.

[aleksandar.kasabov]

Hello Anna1 ,

In order to use Material ID to create a mask you need to add Material ID render element. You will then be able to see the mask in the render channels. Please check the video recording below.

http://ftp.chaosgroup.com/support/0HLqMwWsTG.mp4

I hope this is of help.

[Anna1]

Hi Aleksandar,

thanks a lot for your help. It is kind of working, but if I am rendering the image in the picture viewer, my Material ID is nearly black.It is in such a dark shade of grey, that it is hardly visible.
Do you have an idea, why this is happening? And is it possible to create for every material an own Material ID channel? For example I have a cube and on each side another material and would like to have a Material ID from every side as its own alpha channel.

[aleksandar.kasabov]

Hello Anna1 ,

Hi Aleksandar,

thanks a lot for your help. It is kind of working, but if I am rendering the image in the picture viewer, my Material ID is nearly black.It is in such a dark shade of grey, that it is hardly visible.
Do you have an idea, why this is happening?

This has already been logged in our internal bug-tracking system under VC4D-436 and I will keep you updated.

And is it possible to create for every material an own Material ID channel? For example I have a cube and on each side another material and would like to have a Material ID from every side as its own alpha channel.

You can set different colors for the material ID of the different materials and then use them as masks in the compositing.

[Anna1]

Hi,

thanks a lot for your feedback. Then I will wait until this bug is fixed.

Have a nice evening
Anna