Noisy cloud shadow edges

[himalofa]

It seems every animation brings a new problem for me.

This time I am getting what appears to be noise on the ground round the edges of cloud shadows. It occurs with 2D as well as 3D clouds and I have spent all day fiddeling with various settings to no avail. It is another of those problems that would not show up in a still, but over several frames it looks like noise on the terrain. Has anyone had this before and is there a solution?

[Tangled-Universe]

What are your atmo-samples and do you use soft-shadows? If so, what is the sampling there?

[himalofa]

Atmos samples are 16. I tried soft shadows at various settings and it did help but the effect was still there. Looking at the ground at the edge of a cloud shadow the ground looks speckled. From a distance it looks rough. The speckles are different in every frame so it shows like noise. I will post an example.

[himalofa]

An example is here

http://www.youtube.com/watch?v=51CjswxHl3k

It is simply a terrain with a landsat image draped over it.

[Tangled-Universe]

I would not go for soft-shadows in an animation, because of rendertimes mainly.

My guess is that you have to increase atmo samples, since 16 is kinda low'ish.
I'd suggest to render a couple of frames with 32 samples and compare them to frames rendered with 16 samples.

If this doesn't help another issue might be the GI quality.
For a scene like this GI detail 1 should be sufficient, but you'd need some more GI samples for smooth non-flickering results, say GI samples @ 4 for example.
What are you using now?

So, first I'd try more atmo samples and then more atmo samples + GI samples.
Hope this helps.

Martin

[himalofa]

Thanks for the help I will try that and report back. I am not using GI at all as last time I tried it in an animation it caused flicker. I will try your advised settings for the GI as well.

[Tangled-Universe]

Thanks for the help I will try that and report back. I am not using GI at all as last time I tried it in an animation it caused flicker. I will try your advised settings for the GI as well.

If you're using fill lights then don't bother about the suggestions for the GI at all.

I think it really is a lack of atsmosphere samples, but you should realize that it could also be a "general" quality problem.
When rendering at lower detail levels everything gets less detailed and less accurately calculated. So only upping atmosphere samples while keeping detail low might still not solve the problem. When you increase detail it might be possible that you actually need less samples than 32.

It's key to find the optimum for your animation, quality-wise but also rendertime-wise of course.

[Oshyan]

I think it may be a general detail issue. What was your main detail setting?

- Oshyan

[Matt]

It is probably caused by inadequate sampling of the clouds. Increasing cloud samples is the best approach. If you don't want to increase render times for the clouds themselves, consider rendering the clouds/atmosphere (or sky) as a separate pass using your original samples settings.

Matt