Arnold Mesh Volume tag and displacement

[peter.fagerberg]

Hello! Sorry if this is really obvious but I just can't figure it out by myself... 😁

So, I'm playing around with the amazing Mesh Volume tag which allows you to create an Arnold volume out of any geometry (forget huge VDBs – it's never been easier to create clouds with a few overlapping spheres!). But the really cool thing is that the Volume shader has a displacement input where you can connect a noise to randomly move the volume's voxels around to create some nice effects.

If I understand it correctly the best noise to use is an Arnold noise in vector mode – like this (I've skipped the "mandatory" Range node for clarity):

However, my volume is always displaced in primarily one direction (towards lower left in forward-facing view). I would expect the volume voxels to be displaced in ALL directions, especially when using a vector noise. This is what it looks like with two identical cubes in the same location; one with a standard material (for reference) and one with a Mesh Volume tag:

So what am I missing? How can I get the "volume cube" to stay put in its original location while still being broken up by a displacement noise? I enclose my little scene file if anyone would like to take a look.

Best regards, ///Peter

[peter_horvath · Accepted solution]

We've got a nice tutorial on the subject: https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_for_cinema_4d_ci_Volume_Tutorials_ci_Normalize...

The noise shader outputs a vector in [0-1] range, that's why the voxels are displaced in one direction. You need to remap the output to the [-1,1] range.

[peter.fagerberg]

Of course, @peter_horvath !! Silly me... I should have known that! Thanks!

And big kudos for the Arnold Mesh Volume and its flexibility. I was fiddling no-end with C4D's Volume Builder to create volumes until I discovered it. Simply brilliant! But I don't think many people know about it, so maybe it's time for a Mesh Volume tag awareness campaign!? If nothing else, it would speed up everyone's cloud rendering! 💭💭

I'm already thinking about the T-shirt! 🙂