Why are the layer mask passes calculated seperately?

[ceen]

Hi,

what is the reason for octane to render the multipasses like layer masks etc. seperately? It is basically just a very simple task programmatically but increases render times a lot. Any explanation for that?

[aoktar]

It's not an available render pass for Octane render. So plugin extracts these from render layer masks per ID. Because of this it has to re-render the frame per maskID. Cyrptomatte is a much better alternative for that in 2018/2019 versions.

[ceen]

Hi,
thank you for the explanation. Does it mean the layer masks are rendering the whole scene again shooting rays into 3d space?
That is of course suprising since native C4D puts them out perfectly in 1 second but it explains the long render times.