black .vdb clouds Tweet

[Rik]

Just started using .vdb clouds but can't seem so make them look like anything other than black smoke from a stack of burning tyres.
Any ideas how to make them look white and fluffy whilst catching the colours of the octane daylight sunset?

I've worked out it needs a volume medium but nothing seems to make the cloud white. The volume ramp textures don't appear to do anything to help.

Cheers

[neonZorglub]

Just started using .vdb clouds but can't seem so make them look like anything other than black smoke from a stack of burning tyres.
Any ideas how to make them look white and fluffy whilst catching the colours of the octane daylight sunset?

I've worked out it needs a volume medium but nothing seems to make the cloud white. The volume ramp textures don't appear to do anything to help.

Cheers

Hi Rik,
The VDBs and their Volume medium can be a bit delicate to setup..

I suppose you are using a OctaneVolume object, with a vdb that has 1 or more channels.
Absorption and scattering are the ones to adjust..
First, in the OctaneVolume object, you can take a look a the values inside each channel, in the Display settings panel, use the 'Channel values' button, for each channel ('Channel setup' popup menu) For example, on a sample vdb I use, the density channel has min = 0, max = 5.42
Then, in the Channel Settings panel, you can adjust the scale of each channel. Values around 20 works fine for my sample.

On the Volume medium:
The Density should be not too high, try values around 10.
You should not need a Volume Ramp to see the cloud colors change..

If you use a Volume Ramp, note that from current version (2023.1.1 - 14.06), there is a new 'max value', (default to 100), that also act like a scale.

Also, I noted that once you create a Volume medium from the OctaneVolume object, and drag and drop it to the material editor, you may end up with a copy of the volume medium instead of an instance, so any change on the copy won't affect the volume.. Make sure to check that you are editing the right one..

If you can post or send me your VDB, I could have a look and check some valid settings.
Thanks

[Rik]

Hi Neon.
Thanks so much for your reply.

I'm not 100% understanding what everything's meant to do but I suspect something isn't right. Maybe with my cloud vdb?
I don't appear to have anything to change when I look at the channel settings...
"in the Channel Settings panel, you can adjust the scale of each channel. Values around 20 works fine for my sample."
I've attached the vdb for you to see if there's an issue with it as requested.

I've also attached a recording which may have some useful info in.

Another issue is that when I add the volume medium map to the volume the cloud vanishes. When I remove the map the cloud reappears.

Thanks for the help.

[Rik]

hmmm. Otoy don't accept .avi or .vdb as acceptable file formats

[elsksa]

This should help.

[neonZorglub]

hmmm. Otoy don't accept .avi or .vdb as acceptable file formats

Hi Rik,
try to zip it
Here are 2 small vdbs for reference:

smallVDBs.zip

(3.34 MiB) Downloaded 58 times

smoke.vdb has only 1 channel (density)
explosion.024.vdb has 2 channels (density and temperature)
Both have quite 'standard' values (in the vdb cells), so it should be easy to setup..


@elskesa : Thanks !

[Rik]

Screen 12-7-2023 (8-7-5).zip

(14.43 MiB) Downloaded 57 times

Hi Neon. Thanks for the vdbs. Still not working I'm afraid. Please have a look at the attached and let me know if I'm missing something. I get no options on any of the channel settings and when I use a volume medium map in the medium slot the vdb vanishes.
Is this something to do with being on 3dsMax2014 I wonder.

I've got the .vdb working in blender with cycles.

There seems to be so many options in 3dsmax octane compared to blender or C4D. For example, they don't seem to have any 'channel setting' requirements. What so these even do?

[neonZorglub]

The attachment Screen 12-7-2023 (8-7-5).zip is no longer available

Hi Neon. Thanks for the vdbs. Still not working I'm afraid. Please have a look at the attached and let me know if I'm missing something. I get no options on any of the channel settings and when I use a volume medium map in the medium slot the vdb vanishes.
Is this something to do with being on 3dsMax2014 I wonder.

I've got the .vdb working in blender with cycles.

There seems to be so many options in 3dsmax octane compared to blender or C4D. For example, they don't seem to have any 'channel setting' requirements. What so these even do?

Hi Rik,

The issue might come the from medium assignment that is not updated correctly in the viewport.. I'll try to fix this in a next release..
>> For now, you need to do a Rebuild All after setting the Volume medium..

Also, when editing the Volume medium, you need to set the Absorption and / or the Scatter to a Color, or Texture, to set the main colors..

Once this work, you can also use a ramp, that will set the color depending on the density value of each cell..

Here is a video with the basic settings .. I hope it works with max2014 .. (I didn't see the material parameters of the Volume medium in you video..)

VDB_Volume_Medium_video.zip

(7.22 MiB) Downloaded 60 times

The scale settings might not be present in other plugins, so I suppose they just use the original values from the VDB cells (sale 1.0) ..
On 3dsMax, it's to allow the use of any VDBs, as, depending on how they are created, the values could be very small or very big, and we could see nothing or a back box..
Values from 0 to ~5.0, like this smoke.vdb seems fine for the Octane engine.. no need to scale much, but you can adjust the different elements (absorption, scattering, emission,..) individually.

Let me know if you can see some colors..
Thanks