Using 3.1.0, optiX albedo/normal denoising just isn't cutting it for my volumetric clouds (which use noise > voronoi > absolute > map range > color ramp > mix value between a clear principled volume and a dense principled volume). Everything else is denoising fairly well, but the volumetric clouds just come out as salt and pepper and look really awful even with hundreds of samples for the denoiser. I'm rendering a hollow world with clouds inside and a sun at the center to make an HDRI for a DND map, so the clouds really need to recognizably clouds etc. I'm sure I'm missing something basic, it's been a while since I did a lot with Blender. Edit: added photos of renders and of settings. My bad: I hadn't seen where to add the images so I just didn't.
If anyone has some higher-level feedback I would like to ask: Does anyone know how I might possibly take a sun and using shadow-casting objects and clouds reduce the light level to approximate full night-time darkness in the regions in shadow? The main obstacle seems to be all the indirect light (can I decrease that, is that something doable?) and that if I decrease the light level using dense volumes it decreases the visibility and drama.
Also, since the distances involved in looking up in the sky and seeing the other side of a hollow sphere the size of the earth should involve a massive loss of detail: does anyone have pointers as to managing decreasing levels of detail?