Velocity displacement in Phoneix FD

[dgruwier]

Turbulence FD for Cinema 4D has a feature called "Velocity Displacement", which creates lovely sub-grid detail at render time, and only requires a velocity (vector?) cache. According to their user guide, "Velocity Displacement warps the field forward or backward in time, depending on the value you set.". Here's the example image from the documentation.

It works better than any sub-grid detail method I've seen, because it actually reacts to the movement of the fluids. In my own tests, it easily triples the apparent resolution of the sim in a very believable way. There are some artifacts in certain situations (especially if you overdo it), but often it actually clears up grid artifacts.

Any thoughts? Is this something that could potentially be implemented in Phoenix FD and/or the VRay Volume Grid?

[Svetlin.Nikolov]

Hey,

Check the Rendering panel - this is the Advection displacement method. You can plug there any texture, but it would work best if you use a Phoenix Grid Tex (or a PhoenixFDTexture if you are in Maya), and set that texture to use the Velocity channel. You can also use both negative and positive displacement strength values.

Hope this is what you are looking for

[dgruwier]

Absolutely, that's exactly it. I would have never thought to do it like that, but now that I know what to look for, I can spot the example in the documentation. Thank you!

[Svetlin.Nikolov]

Hope it helps you! However, this does not look particularly good in animation, which is a problem with all displacement methods for volumetrics actually... Still frames, on the other hand, can greatly benefit from it

[dgruwier]

I'll keep that in mind. It has worked well for me in Turbulence FD with animation, as long as I kept the effect subtle, so maybe it's a matter of not going overboard. I'm going to do some testing

[dgruwier]

Is this possible to do with the VRayVolumeGrid on a machine that doesn't have Phoenix FD installed?

[Svetlin.Nikolov]

Ah, I think yeah - for Max at least. Not sure if this is there for Maya yet.

[dgruwier]

Oh sorry, should have mentioned I use Maya. Looks like the PhoenixFDTexture isn't available with just the vray installation.

[Svetlin.Nikolov]

Ah, no, you're right - the Phoenix tex is Phoenix-only indeed. However, I think a Phoenix demo would work for this.