Author Topic: Why all the noise?  (Read 788 times)

Offline N-drju

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Why all the noise?
« on: April 11, 2017, 06:59:46 PM »
I'm now making some godrays that are entering a cave through the hole overhead. However, I am getting quite a lot of, what I believe, is noise. Fractal size doesn't make a difference regardless of whether it is big or tiny. GI settings are at their defaults for now. The light area is quite grainy as you can see. Do you know how can I mend this?

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Same from the bottom. These rays would have looked great if not for that pesky noise.

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« Last Edit: April 11, 2017, 07:16:27 PM by N-drju »
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Offline bobbystahr

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Re: Why all the noise?
« Reply #1 on: April 12, 2017, 05:20:57 AM »
what are your settings atm? easier to diagnose with facts present. You might try upping the AA.
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Offline Dune

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Re: Why all the noise?
« Reply #2 on: April 12, 2017, 05:24:01 AM »
And it's rock that's making the shadows, so I'd guess the soft shadow settings also matter.
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Offline N-drju

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Re: Why all the noise?
« Reply #3 on: April 12, 2017, 05:36:27 AM »
Ahhh, gee... You are right. I forgot to post atmo settings. :-[ I will make it up in the afternoon.

@ Dune - Both rocks and that palm (one for now) on the surface. I did not use soft shadows this time, because I heard that the godray effect is lost then...? :-\
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Offline Dune

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Re: Why all the noise?
« Reply #4 on: April 12, 2017, 05:41:27 AM »
No, that would matter, because godrays are mainly beams through clouds, and they have soft edges anyway. Soft shadows has only to do with hard surface throwing shadows. I suppose it's cloud settings then, if you didn't use soft shadows. You should also make your cloud as low as possible (from bottom to top) to save on quality setting..
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Offline N-drju

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Re: Why all the noise?
« Reply #5 on: April 12, 2017, 05:08:32 PM »
Okay, here is a small mosaic of my atmo settings. How does it look to you?

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Offline bobbystahr

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Re: Why all the noise?
« Reply #6 on: April 12, 2017, 07:08:49 PM »
Hmmm, what are you using to make the rays? These settings? If you're counting on the haze good luck, noisy as all get out. I use a localized Ver. 2 Cloud with no Density shader attached.
Ver. 3 Cloud doesn't seem as suitable.
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Offline N-drju

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Re: Why all the noise?
« Reply #7 on: April 12, 2017, 07:21:18 PM »
No density shader attached... Seriously? ???

No, I'm not counting on the haze, come on... Do you think that reducing it could help too?

I also have a cloud layer, though not localized, masked with painted shader so that the "milkiness" of the background is as low as possible.
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Offline Oshyan

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Re: Why all the noise?
« Reply #8 on: April 12, 2017, 07:27:05 PM »
It's honestly still quite unclear A: what your render settings are (if you are using defer atmo or not, and what your AA setting is if so), and B: whether the rays are in just atmo, or cloud as well (I assume the latter based on your description).

In general when you have a very bright area against a very dark one, as in the case of rays against a heavily shadowed background, you are going to get noise without higher sampling levels. If you are using Defer Atmo I you might try increasing AA first, rather than adjusting atmo or cloud quality/sample levels. Though it might be good to determine what the main source of your noise is, whether clouds or atmo. You could do this by adjusting the quality/samples of only one of those at a time and doing crop test renders. If the noise changes when you increase or decrease quality of, say, atmosphere, then you can assume that atmosphere plays some visible role in the noise. It doesn't necessarily mean it is solely responsible for it, but eliminating noise from cloud or atmo is a good first step, then you can adjust the other element(s) to remove the remaining noise.

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Offline bobbystahr

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Re: Why all the noise?
« Reply #9 on: April 12, 2017, 07:30:24 PM »
I generally set Haze at .1 and control the fog for the rays in the Cloud settings. I set it at 2 for Coverage .01 for Density and dial down till it's thin enough. You only need to make the radius of the cloud large enough to cover the affected area.
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Offline N-drju

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Re: Why all the noise?
« Reply #10 on: April 13, 2017, 07:02:03 AM »
Okay, somewhat better now. I unchecked the "Receive shadows" option in the atmosphere and reduced the haze there to 0.55 down from 1.

I also checked the defer atmo option, increasing the AA and detail for a test. Then, in the sunlight settings I also checked the "soft shadows" option back on again, increasing the detail to 17 samples and (very slightly) the shadow diameter.

The rays and light beam look much smoother now, even at low resolutions. There is still some lingering graininess that remains however. It looks decent but maybe it could get even better...
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Offline bobbystahr

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Re: Why all the noise?
« Reply #11 on: April 13, 2017, 04:31:54 PM »
Good stuff, every situation requires a new set up so there's no one path really to the effect but achievable in often different ways. That's what I really love about Terragen...
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Offline N-drju

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Re: Why all the noise?
« Reply #12 on: April 13, 2017, 05:48:04 PM »
Oh! I should probably mention that I also turned off shadows of atmosphere in the sunlight setting and reduced cloud depth to absolute minimum. Did not check it "experimentally" but maybe overlapping object and cloud shadows also produce noise effects. Now it looks like this:

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Well... Not perfect, but at least not as mad as before. I guess what Oshyan says may also be true - that there may be some distortion between light and dark interiors.
"I don't know what 'pokygon' is but I like it."