Definitely appreciate all the comments and thoughts. I was also using Houdini for a couple years in production but I found the workflow extremely slow. While it is an exceedingly powerful piece of software, 90% of the time I don't require procedural workflow for everything...
Also after using Cinema 4D for over 12 years it's difficult for me to switch to other applications especially being more of an artist and less of a technical user...
I have managed to get some extremely awesome looking clouds using Cinema 4D s noises and Arnold. I'm quite happy with all the tools I have at my disposal but I'm really pushing for Corona to have some of these missing features that are more or less in the max version...
I do appreciate the artistic comments I'm still working on this particular piece of art and while there is volumetric atmosphere and of thin Cloud layer they're not very apparent I may need to tweak the settings further.
With all my experience and other render engines Corona is by far the easiest to set up and looks the best in my opinion. I'm sure technically you could get all of these engines to match extremely closely but for some reason in Corona it just is easier to do...
Anyhow can't wait for the next beta update!
- Shawn
Well, ok. I see no other way than compositing the image from different renderers. After all, they do it in movies too.
Baking doesn't make sense if you need a procedural 3D noise.
What I would recommend is to try Houdini. There you can create such things with ease using a non-destructive workflow. It has many presets, free stuff to download and almost everything has OpenCL support. It actually could make most C4D plugins obsolete. Terrain with erosion, vegetation, vdb modeling, fluids, liquids etc. etc.
The built-in Mantra & Renderman engines are quite fast drawing the media, but since you have Redshift, you could install it without any additional price iirc. You'll have more than enough noises for clouds ;-)
The Basic Non-Commercial version is for free,
the other two types depending on how much you make per year, but still, they're within a very reasonable price range.
PS: about your image, forgive me if I'm bothering, it's just one of my pet peeves... Large-scale scenes.
You should add a subtle volume to the scene to fake Rayleigh-Scatter. Also, a second flat, soft cloud layer wouldn't be wrong if it's not overdone. There you wouldn't need fancy scattering.
I also think that a small amount of a multiplied noise layer for the terrain, but also the water, to create a bit more variation could do wonders.