I believe the procedural clouds in V-Ray Sun are likely an approximation and do not perform full ray-marching calculations.
However, we would like to have a way to control the brightness of the shaded areas of the clouds (i.e., scattering).
In other words, we would like a “fake” phase function control.
Submitted on AHA Ideas (VRAYMAX-I-176).
Would it work if you can select the clouds in Cryptomatte and be able to apply Color layers over them?
Submitted on AHA Ideas.
With Cryptomatte, it should not be possible to select only the clouds.
When you say “clouds,” do you mean the Sky Background, including the sky itself?
If that is the case, adjusting the background brightness would also change the brightness of the sky.
Also, what we want to adjust is only the shaded parts of the clouds (the shadowed areas).
We do not want to adjust the entire cloud brightness.
Submitted on AHA Ideas.
This is the control (illustration shows Phoenix)
Submitted on AHA Ideas.
If we take the image above, we would like to allow selecting the white clouds in VFB, and then you could apply exposure control only on the selection, which obtains the clouds, not the gray background. In the exposure settings, you could change the shadows or dark tones only.
We have a plan for such a workflow.
Submitted on AHA Ideas.
Ah, I see—you mean that if we can create a mask for the cloud portion of the sky, we could adjust it in compositing.
Yes, that approach would certainly be better than nothing.
Submitted on AHA Ideas.
Is it going to work for your use case? If yes, I can decline the idea. Otherwise, I will ask the devs whether a phase function is possible. But we definitely know that there is a demand for the “Mask” approach, and it is already kind of planned for research.
Submitted on AHA Ideas.
This request comes from my customer, but I believe the mask approach should work for our use case.
Therefore, it’s fine to decline this idea.
We look forward to the mask approach. Thank you 
Submitted on AHA Ideas.
Thank you!
Submitted on AHA Ideas.
AHA Ideas status: Declined.
Set during AHA Ideas to Discourse migration.