Custom coloring of volume density?

[Janmansilver]

Hi there

I would like to be able to custom color the density of a volume according to velocity values, but how? Think of it as a kind of high end engineering visualization.

In Arnold one can simply use the Volume Sample RGB shader to "sample" vector values that then can be fed into the color of the density/scatter. I can't seem to figure this out with Octane?
https://support.solidangle.com/display/ ... Sample+RGB

Also, any news on supporting attribute values such as color with regards to shading? Are there any workarounds at the moment? Can the data be fed into the stand alone version, if it is a plugin limit?

[juanjgon]

Hi!

Well, you can now shade any volume grid using a ramp, but the main problem is that the velocity is a vector grid with three components, and the density is a scalar grid. Attached you can see how I can visualize the vel.y component using false colors, but the problem is that this is not the full velocity magnitude ... if you need this feature, I could add an option in the plugin to compute the velocity magnitude from the three velocity grids vector, to use them in the scalar grids.

Octane currently doesn't support custom geometry attributes. This is planned feature along the 3.x dev cycle, but I will try to find some workarounds if this feature is delayed.

-Juanjo

[Janmansilver]

That would be awesome, if it is not too much trouble, thanks

[juanjgon]

In the next build you will have some new parameters in the volume options tab to set an additional vector grid (the velocity or other) and use the vector magnitude values to fill the absorption, scattering or emission grids. I hope this helps.

-Juanjo