Realistic VDB cloud

[Stefan-L]

@pokoy: ok good to know, i will try constant later

@thacmac: if you adapt the scale this goes away, but i found it quite realistic as also in reality clouds are darker where they are thicker if light comes from behind, or not?
maybe share a setting, so we can play and try with it ? :)

[thacmac]

If you use the density channel for scattering you are basically diminishing it where the density increases - while it gives you some additional artistic control, it's technically wrong. Scattering should be a constant color, and then play around with the value - it has a ceiling value where it won't change with increased values. It should produce a better result.

I always set scatter to 100% white, no channel at all. So, please take it seriously and accept that Corona volume is not deep scattering enough for cloud.

[pokoy]

If you use the density channel for scattering you are basically diminishing it where the density increases - while it gives you some additional artistic control, it's technically wrong. Scattering should be a constant color, and then play around with the value - it has a ceiling value where it won't change with increased values. It should produce a better result.

I always set scatter to 100% white, no channel at all. So, please take it seriously and accept that Corona volume is not deep scattering enough for cloud.

If you mean my response, I was referring to Stefan-L, not your tests.

I'm really taking this seriously as this is important for my work, and I have done many tests and am a bit torn on this topic myself. But to make it a serious conversation, not just a random "Here's a better looking result" thread, my question still is - what is the *other renderer* in the pic you posted?

[burnin]

Notes to whomever
 Take into account retro-reflective properties of water droplets/mist - so set directionality accordingly
also, set sample intensity & ray depth as high as you can afford, otherwise clamping occurs :(

EDIT
There also seems to be a kind of bug w/ use of VDB grid - roughness on sphere is gone inside the grid... (?)

[bnji]

Hi there,
Could you please provide some examples of your work and the result you're looking for?
This to better understand the issue.
Kind regards.

Hi,
Would you mind to report this to dev team?
Please !

Hello again. Could you please provide your scene so we can try reproducing the issue and better understand your settings/workflow?
Kind regards.

[Beanzvision]

EDIT
There also seems to be a kind of bug w/ use of VDB grid - roughness on sphere is gone inside the grid... (?)

There is indeed and we have it reported already ;)
(Internal ID=1011646126)

[maru]

Hi all, thanks for the discussion and examples. We understand that cloud rendering (and volumetric scattering in general) can work differently in different renderers. Some improvements are possible in Corona, but at this point we do not think they are critical to Corona development (creating ultra-realistic clouds / volumetric effects is not so common among Corona users).

If I am not mistaken, the realistic-looking clouds with strong silver lining or the darkening effect would require what we have already logged as a feature request under "blending several phase-functions in a single volumetric material".
Currently, you can create with Corona a volumetric material which has uniform scattering (same scattering towards and away from the light source), forward scattering (more light is scattered further from the light source than bounced back into it), or backward scattering (more light is bounced back into the camera than passes further). This is controlled using the directionality parameter. What is currently not possible is blending those behaviors in a single material (e.g. a material which would have +0.9 and -0.9 directionality at the same time and this would be blended together) or using some special "curves" to define the scattering.

(Internal ID=1060972842)

[thacmac]

Hi all, thanks for the discussion and examples. We understand that cloud rendering (and volumetric scattering in general) can work differently in different renderers. Some improvements are possible in Corona, but at this point we do not think they are critical to Corona development (creating ultra-realistic clouds / volumetric effects is not so common among Corona users).

If I am not mistaken, the realistic-looking clouds with strong silver lining or the darkening effect would require what we have already logged as a feature request under "blending several phase-functions in a single volumetric material".
Currently, you can create with Corona a volumetric material which has uniform scattering (same scattering towards and away from the light source), forward scattering (more light is scattered further from the light source than bounced back into it), or backward scattering (more light is bounced back into the camera than passes further). This is controlled using the directionality parameter. What is currently not possible is blending those behaviors in a single material (e.g. a material which would have +0.9 and -0.9 directionality at the same time and this would be blended together) or using some special "curves" to define the scattering.

(Internal ID=1060972842)

Thanks so much for replying. I still think that this should be improved in both speed and behaviors ( using blending like you said ). It may not be a priority right now, but I truely hope it won't be a long delay. Because today's renderers are all very advanced and users are always demanding more and more for quality and volume is a very important thing.