How to ramp Volume Density? Tweet

[Berube]

Hello everyone,

I've been trying to create a gradient in a Volume and can't seem to figure it out.
I tried the "Volume Ramp" also (which doesn't seem to do anything either) via "Density", "Scattering Tex" or "Scat. Ramp" and no changes take place.
I would like to use the same approach to add noise to a Volume but when I connect a "Noise Tex" in the Density, nothing happens either.

I have a feeling this is not working on the OSX PR13 Octane build but want to double check to make sure its not a user error prior in reporting the bug.

Thanks for your help.

-Berube

http://www.johnberube.com

A. MacOS Monterey 12.2
B. AMD Radeon Pro Vega II Duo 32 GB
C. 384 GB 2933 MHz DDR4
D. N/A
G. Octane PR13 Blender

[jobigoud]

In the normal Volume medium node the Density property is a single number not a texture, it looks like Blender lets you plug a texture there but it is converted into a single number and will be the same for the whole volume. In Octane 2022 there is the new Standard volume medium, there the density is a texture and you can have a gradient controlling it. In earlier versions you will have to combine your gradient/noise with the absorption and scattering. It should be a 3D gradient or noise though, the volume density exists at any point in space inside the volume bounds so the gradient texture must be able to produce a value at any point.

[Berube]

Hello Jobigoud.

Earlier Octane version? I'm using the latest build. Isn't PR13 the latest build available and didn't it come out in 2022?

As for the Volume node, I only see the Volume Medium node. Where can I find the Standard Volume Medium node?

When I connect a Gradient Tex node in the Scattering slot, it gets reduced to a solid color.
As for the 3D Gradient note, I only see the "Gradient Tex" node. Is this what you are referring to?

If so, how do I plug the orientation and coordinate for the grad?

Would love to see a screengrab example. I have a feeling some of the nodes are missing on the OSX PR13 build, or some of the widgets are broken.

-Berube

[jobigoud]

Sorry I didn't mean to imply you weren't using the latest version, just that the Standard volume medium is only going to be present in Octane 2022 (only the XB0 was released so far).
Are you looking to create a sort of cylinder-shaped cloud with fading density at the top, or a solid object with sub-surface scattering that lets light penetrate more or less deep into the object?

[Berube]

Hello jobigoud,

Thanks for your reply. I'm trying to create a Volume Fog with a vertical Density attenuation falloff driven by a vertical ramp/gradient.

I would also like to drive the absorption with a color gradient, where the thicker the fog, the more of a color is absorbed, and the thinner it is, the more of another color is absorbed.
Would also like to do the same for the Scattering Tex/Ramp as the documentation and naming of the widget suggests.

At this current time, all gradient connected to either, Scattering TEx/Ramp are brought down to a single color, which seems to be the median of the provided ramp.
A gradient from Black to White plugged in the Scattering Tex, or [b]Scat. Ramp[b] creates a 50% grey Scattering value for example... Although the documentation says otherwise.

Again, I would try the above information on OSX as the OSX build (PR1#-13) have been inconsistent with PC feedback almost every time. What you may see on your PC side is often not what I see on the OSX side.
I've read all the docs available and when I plug things together as per the documentation, it doesn't work.

Best,

-Berube

http://www.johnberube.com

A. MacOS Monterey 12.2
B. AMD Radeon Pro Vega II Duo 32 GB
C. 384 GB 2933 MHz DDR4
D. N/A
G. Octane Blender Plugin PR13

[linograndiotoy]

That's not going to work with geometry. You would need a VDB volume with the shape of a cylinder.

[Berube]

Hello Lino,

Thanks for the hint. I got it working after watching your cloud/noise tutorial. I can't believe how fast your machine is.

-Berube