Author Topic: Overlapping cloud layers going crazy-ass  (Read 546 times)

Offline N-drju

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Overlapping cloud layers going crazy-ass
« on: January 30, 2018, 04:48:24 PM »
I'm not sure if this topic belongs here, but I do consider it a bug or at least a feature that needs more work. And I'm really angry with the way TG handles this kind of stuff...

I am now after an overcast layer of clouds. I added yet one more layer of clouds to add some billows to an otherwise flat cloud base. However, the cloud layers don't "talk" to each other really... It's like each layer is propagating and scattering light on its own with no consideration of what's above or below them! Instead of some nice, wavy effects, it produces another cloud layer which is simply nothing more than a field of oddly colored blobs:

78938-0

This is really uncalled for. I find it deeply troubling that, for instance, Martin's a.k.a dandelO's ages old metacloud solution (back from the days where TG did not support localized clouds) does not produce such effects no matter how you arrange the clouds and it is still very versatile!

If you guys at Planetside could perhaps show me a way how to cope with this problem or explain why the clouds behave that way, I would sure appreciate it. I don't want to be too harsh, but it really makes me sad to see a good idea going straight into the trash bucket, because the clouds behave this way. :(
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Offline pokoy

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Re: Overlapping cloud layers going crazy-ass
« Reply #1 on: January 30, 2018, 05:29:10 PM »
Are these v2 or the new v3 clouds? I remember reading that v3 clouds don't interact (yet) so shadows generated by one cloud layer wouldn't be visible on another one, I could be wrong though...
FWIW, I know I've used several layers of v2 clouds in the past and this worked fine in a similar scenario.

Generally, volumetric effects probably add up right now (so two layers with a density of 0.5 would add up to 1.0) but I agree that we could have a mode where they blend to produce one volumetric cloud instead, one could do some cool effects that way.

Anyway, curious to see if this can be solved.

Offline N-drju

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Re: Overlapping cloud layers going crazy-ass
« Reply #2 on: January 30, 2018, 05:35:59 PM »
Well, these are actually V2 clouds. :-\ It's even more confusing now...

If you could give an example on how you managed to "blend" cloud layers though, settings or tgc., I would sure be grateful.
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Offline pokoy

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Re: Overlapping cloud layers going crazy-ass
« Reply #3 on: January 30, 2018, 06:29:06 PM »
I'm trying to save out the cloud nodes from that scene I mentioned but I have a problem where TG will hang when attempting to load or save files/clips and it just hangs now. I'll keep trying... hopefully I'll have something for you to try out by tomorrow, it's late here already. Will keep you updated.

Offline Matt

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Re: Overlapping cloud layers going crazy-ass
« Reply #4 on: January 30, 2018, 06:55:33 PM »
With Cloud Layer V2, the way light is propagated from one cloud layer to another is through the GI cache. The "light propagation" parameters don't transmit light between cloud layers, only within the same layer. Therefore Cloud Layer V2 usually doesn't handle this kind of scene as well as Cloud Layer V3 can, but it might be possible to tweak your GI settings and/or the colour of your lower clouds to make them look more integrated. I would start by looking at the following settings. GI quality at least 4. Cloud colour in each layer: 0.25. In the upper layer, reduce the light propagation setting and try to get the upper layer to look good with the lower setting (perhaps by reducing the density to compensate for the lower amount of light propagation). This will reduce the difference between the amount of light reaching the upper and lower clouds, and perhaps if the upper layer has a low enough density you will get some sunlight reaching the lower layer. Finally, raise the colour of the lower layer slightly to compensate for it being darker.

These changes might get you closer to a realistic result. But if you can use layers of Cloud Layer V3 instead, you'll probably get better results and more detail in the lighting of the lower cloud. You might only need the lower cloud to be V3 to get this benefit, depending on how closely they overlap, but it's probably safer to change both of them.

Matt
« Last Edit: January 30, 2018, 07:00:47 PM by Matt »
Just because milk is white doesn't mean that clouds are made of milk.

Offline N-drju

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Re: Overlapping cloud layers going crazy-ass
« Reply #5 on: January 30, 2018, 07:27:57 PM »
Thank you for describing the workflow in such detail Matt. As I said, I don't mean to be a pain in the back, but still... I figure it is very difficult to translate something as complicated as clouds into an entirely virtual life.

I made some more tests and it seems that "receive shadows from surfaces" option helps a lot! Maybe not quite there yet, but much better. At least in the test scene I just drafted. I should have thought of that before... ::) It has to be enabled in both layers though.
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Offline pokoy

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Re: Overlapping cloud layers going crazy-ass
« Reply #6 on: January 30, 2018, 07:30:16 PM »
That's interesting, Matt. I love the new v3 clouds and reading this there's really no reason to use v2, other than speed maybe.

N-drju, I managed to save out the cloud nodes and loaded them into a new default TG file, attaching the file. It's exactly the same setup as used on this render:
http://www.planetside.co.uk/forums/index.php/topic,18224.0.html

There are two cloud layers, they aren't intersecting right now so not really a solution to your original problem. I might be a good starting point however. There's a ground level dust cloud, might not be needed but I've kept the entire setup untouched.

Below is a render of this file, you might need to increase quality of the cloud layers or increase AA settings to get rid of the noise.


Offline Matt

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Re: Overlapping cloud layers going crazy-ass
« Reply #7 on: January 30, 2018, 07:36:43 PM »
I made some more tests and it seems that "receive shadows from surfaces" option helps a lot! Maybe not quite there yet, but much better. At least in the test scene I just drafted. I should have thought of that before... ::) It has to be enabled in both layers though.

I don't know why that would help in the render you posted, because no surfaces are casting shadows on your clouds. I guess it might just be a coincidence, and other randomness in the GI solution might be giving you better results (if you haven't changed anything else).

Matt
Just because milk is white doesn't mean that clouds are made of milk.