Cloud Quality levels change image drastically

[ASK51]

Hey,

I just noticed this issue after doing my latest render. I made a sky with 3 cloud layers and I used the default cloud quality settings and 32 atmosphere samples. I only rendered in 2k as well to get a quicker render and see if I like the image.

What I got was this:
[attach=1]

I liked what I got, so I increased the quality of each cloud layer to 2 and raised the image resolution to 8k and started an overnight render. When I checked the image this morning I was slightly confused as it looks like this:
[attach=2]

I am wondering now how the colors can differ so drastically from each other? I really wanted to render exactly the same image just in higher rez and less noise. I didnt change any other settings.
Any idea what could be causing this? I actually spend quite a few hours getting the first result and I dont really have the time to tweak this new highrez image to get back to where I started with the lower quality one. Also, I think this just shouldnt happen.

Would love to get some more insights on this

EDIT: and this is with the latest version of TG4

[Oshyan]

Try reducing Cloud Quality back to 1 and then, if there is noise, increase AA (assuming Defer Atmo is enabled, as it is by default). That should reduce noise while maintaining the same look of the clouds. If not perhaps you can share the TGD scene file with us for troubleshooting purposes?

- Oshyan

[ASK51]

Hey Oshyan,

thanks a lot for the tip! Have a new render up and running and will keep you posted on this!

On a side note though I really have to say that TG4 is amazing so far! Its still hard to find my way around everything especially in regards to what does what (I am totally new to Terragen^^)...but overall, the realism and quality that can be achieved is mind blowing! Really loving it.

Are you guys planning on updating the documentation now that TG4 is out? I find it quite hard to find up to date documentation and information as well as simple example files or tutorials for TG that are not super outdated

Thanks a lot and cheers!

[Oshyan]

Thanks, glad you're enjoying TG4! Indeed we do plan to update the documentation, and we're also working on partnerships to produce more educational video content as well. GeekAtPlay should have some new content in the relatively near future...

Can you let us know if the settings suggestion doesn't fix your problem? The new v3 clouds are still being optimized and finalized and your feedback is helpful.

- Oshyan

[ASK51]

Hey Oshyan,

thanks a lot for the info...that sounds great and I am looking forward to it!

Regarding the settings, so I have mixed results now. I am using 2 easy clouds layers and 2 cloud layer v2 (I added them via the menu in atmosphere and not via nodes) The 2 easy clouds are just some clouds, while the first cloud layer v2 is a cirrus layer and the second one is some large, not very dense overall cloud to make the sunset colors scatter across the whole sky.

They all have quality 1 now besides that last cloud layer v2 with the big foggy/misty cloud which had a default of 0.25. I had AA per default on 2 and increased it to 8 and that made the rendertimes explode so much that I actually cancelled twice (one was a 4k render and the other one a 2k).

I will try to play around with this a bit more today, but it seems that AA really has a very strong impact on the rendering times while it might not being able to get rid of the issue completely but lets give it a shot and see

I will keep you updated!

Thanks again

[ASK51]

Alright, I did another round of testing and AA definitely helps. However, having a 4096x2048 sky, using default cloud quality and 4x AA increased the render time from around 1h to 3.5h and still didnt get rid off the noise completely.

I need to render 8192x4096 in the end so I would love if there would be more efficient ways to reduce the noise in regards to rendering time.

I noticed that in the render tab, there is a button GI settings and there is a tab called "GI in Clouds" which is set to Still/Medium. Would you say its worth trying out to set this to Still/High or Still/Very High? Or is this not related?

Also, I read that increasing the atmosphere samples can help reducing grain in the shadows so I might give it a hot with 64 samples

One last question....whats exactly the difference between easy cloud and cloud layer v3? Everytime I use easy clouds it looks very natural vs. cloud layer v3 which does some nice volumetric shading, but feels very CG like.

Thanks and cheers!

[Oshyan]

When Defer Atmo is enabled (by default in TG4), AA has the most significant on both level of noise and render time for clouds and other atmosphere elements. AA4 or 6 (at most) should be fine for any scene without significant numbers of objects in it. When objects are involved you often need to use higher AA and then you need to start getting to know the "adaptive" settings better to get good render times with Defer Atmo enabled.

The GI in Clouds will affect the quality of the lighting in the clouds, but not the level of noise. I would not suggest changing it. Higher settings will also increase render time further.

Increasing atmosphere samples can help with noise but you have to really be sure that the noise you are seeing is coming from the atmosphere and not the clouds. Often it is in the clouds. Only dark scenes or heavily shadowed scenes tend to have atmosphere noise. You can test it by enabling a small crop region and rendering with your current atmo samples (or default, 16), then increase to 64 as a test. I would *strongly recommend against* atmo samples of 64 for any final render when Defer Atmo is enabled. You will get very high render times. *If* you determine that atmo is the cause of some of your noise, then you should try something like 24 or 32, but not 64. It should not be necessary to use 64 except in the most extreme circumstances (again, this only refers to when Defer Atmo is enabled, and assumes that AA is 4 or more).

Easy Cloud is a new cloud *shape* model that uses v3 shading internally. So the shading qualities should be (potentially) the same as manually created v3 clouds, but the actual shapes, density profile, and specific settings for lighting will be optimized for the specific cloud type. Basically, you can achieve similar results to Easy Cloud with a lot of work setting up complex Density Shader networks for your clouds, and getting the right settings for your v3 scattering parameters (in other words the potential is there in the default v3 setups). But it's easier to use Easy Cloud, which is why we made them.

- Oshyan

[ASK51]

Thank you very much Oshyan! Highly appreciate the help and insights!

I will play around a bit more, but I also have to focus on finishing up those skies so we can use them I am actually fooling around with some noise removal plugins in PS and Nuke to get the most out of it because I have an 8k render running since 15h with 4x AA
Thats a bit much since I can render over night, however it would be nice to have it the next day^^

Yeah, its a bit tricky all in all since we really need that high resolution and results as noise free and realistic as possible cause it will be used as video game skies (and maybe even on 4k screens). I might be able to share some of that stuff later down the road when everything is finished

Cheers and thanks again!

[Oshyan]

Sounds good, we'd love to hear (and see!) more about your work when possible.

- Oshyan