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I'm trying to get some volumetric lighting going for an underwater scene, but I can't get a handle on the noise in the fog at all. Have read countless posts and played with all the settings, but this is the best I get. It's for an animation so I cannot have gigantic render times per frame. =(
There's a bunch of Octane Lights in the geometry that all work together, and a daylight with a scattering medium.

What am I doing wrong?

Hi designandcode,

In V4 Otoy have introduced AI light system which helps calculate path tracing of small light sources. Also they've introduced AI Denoiser which now supports Volumes
So to get rid of the noise you need to slightly change your octane's render settings:
1) Turn on AI light, to narrow down sampling of small lights
2) Increase your Parallel samples from 8 to 32 (in a recent RC it can be set more than 16), which will increase your overall render speed. But be aware, increasing of Parallel samples will consume slightly more VRAM
3) Turn on Denoiser on completion and check Denoise volumes

But even with those settings 4000 samples won't be enough to get rid of the noise completely , so you need to increase them as well
At the moment volumetric fog with beam of light is still really expensive in terms of render time. Otoy showed preview of Vectron/Spectron technology in future versions, and claims that it will completely change calculation time of such effects and make it less painful

Also I checked your scene, your Adaptive sampling is set to 0.03 which won't affect a lot of pixels in the image and create black dots and they don't disappear even on 100 000, you need to change it to lower value, for example 0.01

Cheers

SergKlyosov wrote: 1) Turn on AI light, to narrow down sampling of small lights
2) Increase your Parallel samples from 8 to 32 (in a recent RC it can be set more than 16), which will increase your overall render speed. But be aware, increasing of Parallel samples will consume slightly more VRAM
3) Turn on Denoiser on completion and check Denoise volumes
Cheers

Hi Serg, thanks, I've switched to V4 and tried your settings. Even at 16000 samples and adaptive sampling at 0.01 with the denoiser on I do not get anything remotely usable.
Is there anything else I can try?

I think Paride can give you more comprehensive answer on that topic

I ran some test and even at 256 000 (which is maximum in the kernel setting) I still have noise in your scene

could you convert max 2014 or 17 i want to test it

Hi twinsk8,
In interior renderings, I would use fog cube with specular material.
light sources must not intersect geometry because they generate noise.
active. if you do not use Octane room, the denoise settings are in imager.
Regards
Paride

paride4331 wrote:Hi twinsk8,
In interior renderings, I would use fog cube with specular material.
light sources must not intersect geometry because they generate noise.
active. if you do not use Octane room, the denoise settings are in imager.
Regards
Paride

Hi Paride, thanks for your reply. Unfortunately this is not an interior scene - it's a subsea environment. Is there any way to use the volumetric fog without a room?

I've also downloaded your scene and had a look - unfortunately I get warnings about missing .IES files and the render comes out nearly completely white.

Hi designandcode,
I'm sorry, here is a correct .zip file.
Yes you can use fog cube in external:
viewtopic.php?f=27&t=59549&p=304625&hilit=fog#p304633
a suggestion to avoid noise, Octane materials:
specular < 1
roughness > 0
Regards
Paride

designandcode wrote:I'm trying to get some volumetric lighting going for an underwater scene, but I can't get a handle on the noise in the fog at all. Have read countless posts and played with all the settings, but this is the best I get. It's for an animation so I cannot have gigantic render times per frame. =(

noise.jpg

There's a bunch of Octane Lights in the geometry that all work together, and a daylight with a scattering medium.

What am I doing wrong?

material-tests-tmp.zip

we tried the same and it looked very bad with underwater volume light. I think unless otoy will add it as an option like vray has we will never be able to have volume light with different volume intensities and independent from environment. That's sad because it is an important feature.
In Jurassic World, the fallen kingdom movie the beginning scene has the sub with volume lights. I think those were volume lights and independent from the environment. That's what we need https://youtu.be/i_4kMiM9Aw0?t=7

Hi Paride,

thank you very much - I've been playing with this and it is much better than before, although I still get render times of 2+ hrs per frame in my full scene.

Also, is there a way to get a better falloff of this light?

If you look at this example image:
You can see that the light is very bright at the beginning and then falls off very quickly the greater the distance.

In your file, the beam is too uniform and doesn't really show any falloff. It's not bright enough right at the lamp and too bright when it reaches the teapot.
I've tried to play with density and scattering, but it only seems to affect the brightness of the beam overall and doesn't change the falloff. Any tips? =)

coilbook wrote: we tried the same and it looked very bad with underwater volume light. I think unless otoy will add it as an option like vray has we will never be able to have volume light with different volume intensities and independent from environment. That's sad because it is an important feature.
In Jurassic World, the fallen kingdom movie the beginning scene has the sub with volume lights. I think those were volume lights and independent from the environment. That's what we need https://youtu.be/i_4kMiM9Aw0?t=7

Yeah, we're struggling here too. Right now we are aiming to put it together in post, with an HDR rendered base scene and a separate light pass from the volume lights above. It's very hacked together but I don't really see any other option.