Noise in clouds

kentm · June 21, 2019, 03:36:32 PM

Hey team,

I'm about to start refining a cloud layer and am asking for any pointers before I get going from anyone who may care to offer it.

The problem is that I'm seeing a high amount of fine noise at the edges and want to get it to a more natural look while keeping the same basic shaping.

Below are a couple images illustrating what the current "look" is and shots of the settings I currently have. The Node I need to adjust is a "Density Fractal" that's feeding into the "Mask Shader" of an "Altocumulus Castellanus".

If anyone can offer any tips on where to start adjusting I'd be super grateful as with my current level of inexperience I'm just going to start mashing around.

Thanks again!
K

[attach=1]

Oshyan · June 21, 2019, 03:59:07 PM

That noise appears to be a render quality issue, not something inherent to the noise functions you're using to generate the cloud shapes. What is your antialiasing setting for rendering? As well as your cloud Quality?

- Oshyan

kentm · June 21, 2019, 04:12:39 PM

Ah! Dang, Of course. I should have thought of that... now I'm embarrassed.

Thanks, I'll dig into that.

kentm · June 21, 2019, 04:16:00 PM

render settings are:
[attachimg=1]

Oshyan · June 21, 2019, 04:21:54 PM

Yeah, so enabling Defer Atmo will help a lot with the noise, but may increase render time (any solution to the noise will do that however). If noise is still an issue with Defer Atmo enabled, then increase AA. I would not go above 6 for an atmo-only render. If noise remains at AA6, try increasing Cloud Quality. If these are v3 clouds, you can also try increasing Voxel Scatter Quality, make sure it is at least 100, and you can try up to 200. However as far as I know this should affect edges much less or not at all, so it would be more for noise within the shading of the cloud volume (e.g. shadowed areas).

- Oshyan

kentm · June 21, 2019, 04:24:18 PM

Excellent, thanks again.

WAS · June 22, 2019, 02:51:00 PM

I use freeware, and I often turn up voxel scattering quality (under GI in clouds) from 100 to 150 and it seems to help a lot with noise in both the atmosphere and clouds with thin shapes.

Oshyan · June 22, 2019, 03:04:48 PM

Voxel Scattering Quality doesn't affect the atmosphere, but it does affect v3 cloud shading and noise there quite a lot. It's definitely a good setting to increase when there are cloud noise issues because it tends to have a lesser render time impact vs. increasing AA, reducing pixel noise threshold, or increasing cloud quality.

- Oshyan

WAS · June 22, 2019, 03:15:09 PM

Quote from: Oshyan on June 22, 2019, 03:04:48 PM
Voxel Scattering Quality doesn't affect the atmosphere, but it does affect v3 cloud shading and noise there quite a lot. It's definitely a good setting to increase when there are cloud noise issues because it tends to have a lesser render time impact vs. increasing AA, reducing pixel noise threshold, or increasing cloud quality.

- Oshyan

Oh that's right, I'm thinking of when I used to increase atmosphere samples (16 to 32). I have a custom start project now so forgot.

Additionally, when dealing with (3d) v2 clouds, and thinner shapes I found increasing it's voxel count in it's settings help a lot as well, though this will increase render time, but often small bumps go a long way.

Oshyan · June 22, 2019, 03:49:07 PM

Voxel Count won't affect noise, but will affect detail.

- Oshyan

WAS · June 22, 2019, 08:07:08 PM

Quote from: Oshyan on June 22, 2019, 03:49:07 PM
Voxel Count won't affect noise, but will affect detail.

- Oshyan

That makes sense. Overall though I usually bump voxel count, scattering quality and cloud quality and get noiseless clouds.

Voxel Scattering 150
Cloud Quality 0.5
Voxel Count 50/100 (depending on density)
Antialiasing 6

kentm · June 25, 2019, 02:59:53 PM

thanks for posting those numbers, it's helpful for me.