Render Clouds as holdout but keep their shadows

[dorianvan]

Is it possible to render clouds as holdout but keep their shadows on the surface? I have the clouds as a separate render layer/group, but whatever I do the clouds are still there.

[dorianvan]

So I got it to render without the clouds by plugging clouds into a new planet, then moving the entire atmosphere into a hide atmo group, then making the object invisible, but cast shadows on, and all other objects visible/cast shadows on. Works out decent, but is not perfect. Not quite what I was after. How do I simply hide the clouds, but keep their shading on the ground?

[cyphyr]

On the Cloud tab there are three check boxes at the top left.
Try un-checking "Enable Primary". You scene should render with cloud shadows but no clouds. Note you will still get the shadows cast through the atmosphere unless you disable that separately.
Hope this is what you're after.

If you want the shape of the clouds to still be rendered you can colour them black. This would work as a hold out of sorts.

[dorianvan]

Thanks Richard, that actually works about the same as the new planet, except you get the sky in rather than black, which saves alpha comping, however good that is. Both grounds actually differed from the main one with the clouds. I think I figured the reason why. There is specular all over my ground objects (grasses), and when the atmo is either black or primary disabled, the specularity is receiving something different than the main clouds. Not really a big deal, but thank you again for the help (I'll probably go with the disabled primary).

[Matt]

Disabling primary visibility on the clouds shouldn't change anything else in the scene. If you can send me an example I'll take a look.

Matt