Material IDs with Alpha channel.

[LL_Will_J]

Hi,

Is it possible to use the alpha channel of a material ID as a 4th channel? It seems like it would be handy to have a fourth channel for masks.

But not really sure how you could assign the colour (as there is no alpha in the colour picker).

Cheers!

[tashko.zashev]

Hi,

I assume that you are using Multimatte render element with material ID's ?
You can always add more multimatte elements to your setup in order to get all of the masks you need.

Could you share more details about your request?

[LL_Will_J]

[ATTACH=CONFIG]19960[/ATTACH]

I have attached an image to try and show what I mean. For a multi matte render element you only have the option to use 3 channels RGB (as shown in the green square). But I am wondering if it is possible to use the Alpha as an extra channel (as shown in the pink square).

I understand you can use as many Multi mattes as you want - so it is easy to work round this problem.

But having the extra channel would mean that if you needed 8 unique mattes for objects in your scene you could set that up in 2 multi matte passes instead of 3 (so less setup and passes in the comp).

Hope this makes sense.

Many thanks

Will

[tashko.zashev]

Hi,

Thank you for providing more details.
Probably this setup will be possible at some point when we implement support for each render element alpha channel.
For now the only option is to add additional multimatte element or to use Object ID render element.

[LL_Will_J]

Okay - its good to know I am not missing a trick.

Playing around with the render elements - I now see that the same alpha is used for all the different passes.

But I think having some flexibility in the alpha channels of render elements would be cool functionality (especially for extra tex and so forth).

Thanks for your help!