Xparticles OpenVDB mirrored in VDB volume

[ounocreative]

Having an issue using a fire animation generated in xparticles.

The animation consists of a cube on fire that rotates 360 counter clockwise, I cache the animation to openvdb and load it into a vdb volume. Once I do this however the whole animation is mirrored and rotates the opposite direction.

The xparticles cached preview shows a correct animation with the object and fire rotating correctly however vdb volume is mirroring this instead.

I've tested this in a new file with basic shapes and it does the same thing. Right now my only solution is to cache the fire animation rotating in the opposite direction so its the correct way round once imported into the vdb volume.

I don't know if theres an option I'm missing but I can't see anything related to rotation direction in either xparticles or the vdb volume, perhaps there is something missing with regards to support for files generated in xparticles.

Any thoughts?

[Loopinglovers]

Hey Mate,
i just run into the same Problem - did you discover a workflow to fix it allready?
cheers

[aoktar]

What's up with V4.00 stable?

[ounocreative]

Hey guys

Wanted to provide an update on this issue as I have recently revisited it and its still present.

This is using the latest version of XParticles and V4.03 of Octane.

It seems to be related to the Z axis. In the this screenshot you can see my animation of smoke trails following some missiles, this is animated along the Z axis using an attractor. However in the Octane viewer you'll notice the exported VDB being rendered completely mirrored to the actual animation.

In screenshot 2 I have rotated the attractor around to the X axis and rebuilt the cache, this animation seems to render fine in the Octane VDB object, following the same path/size as the previewed ExplosiaFX on the left.

So it seems to be related to Z axis data, I don't know if Xparticles isn't exporting it correctly or if the Octane VDB volume is not understanding it correctly. For this animation I can rotate everything to animate down the X axis but for things that spin in all axis this isn't going to help and a fix is needed,

Hopefully this info is useful in getting it fixed as Id love to have it work properly.

[ounocreative]

Still getting mirrored if you're not dead on the 0 point center of the world.

Am I just missing an option somewhere? Or is this just not supported properly?

It's incredibly frustrating.

[aoktar]

It's incredibly frustrating.

Our VDB loader gives the same results as how R20's vdb loader does.

[ounocreative]

Thanks for the reply.

Definitely seems to be Xparticles then. Tried the same thing at work with R20 and the cinema volume builder and I get the same mirrored version. Must be missing an option somewhere or perhaps theres a bug in the openVDB export in Xparticles.

Will post over on the Xparticles forum, see if we can get to the bottom of this.

[ounocreative]

I finally have a solution thanks to the guys over at Insydium.

Entering a value of -1 to the VDB volumes Z axis for size fixes this issue. Fog volume appears in the right place and the right way around!

Also if you're planning on using Xparticles with R20s volume building it requires the same fix in the volume loader along with a negative value in the Y size axis on the volume mesher!

Hopefully this helps others with the same Xparticles issues.

[helloimneil]

Thank you so much for sharing your solution. I encountered this today and was incredibly bummed to run into this strange problem/bug. Cheers to you, man! Should our paths ever cross I'll gladly buy you a pint.

[chrisfranklin6002]

Jesus this has been bugging me for so long!!! Nice one!!