OTOY Forums

Hi
I'm doing a smoke sim, importing the dop fields, converting to vdb for caching to disk, then converting back to volume for octane render. The result as you can see in the attached video is that the container jitters, probably due to changes in the bounding box. If I render the dop volumes directly it works fine but storage is then increased significantly. I've also attached the hip file.
the jitter appears only in the render, the viewport seems correct.

Thanks
Yaniv

Thanks for the scene. I'll check it as soon as possible.

-Juanjo

Yes, it seems a problem with the bounding boxes origin reference while converting VDBs to Houdini Volumes. I think that you can fix this problem if you enable the "Split Disjoint Volumes" option in the convertvdb node. Can you please try it?

Thanks,
-Juanjo

Hi,
I've enabled the split disjoint volumes option. Now it requires that Full Scene Reload be enabled on the ROP. If I isolate only the density field for the render then it seems stable for at least the duration of 40 frames I've checked. If I isolate density and velocity then there is at least a single jump between frame 5 and 6 but then there is no motion blur option.
Is this fixable on octane's side? Could you explain please why this happens exactly? maybe there is a way I can counter it in houdini.

Thanks
Yaniv

I am not sure, I am investigating why this happens. It is really a weird issue.

-Juanjo

Other workaround if you want to work with VDB cache files, can be export the volume as real VDB files and use the native Octane VDB rendering feature to render it. It seems to work fine without jittering.

To render the VDB sequence, in the pyro_import node you only need to disable the volume primtive rendering and enable the VDB rendering in the OBJ spare parameters.

Hope this helps.

-Juanjo

Good to know as a last resort. Hope this can be resolved in the next builds.
Thanks for the help
Yaniv

I suppose that the definitive solution for this issue is support in the plugin the direct rendering of the Houdini internal VDB volumes to avoid the final conversion node. I'll try to add this feature as soon as possible.

-Juanjo

Perfect. Thanks!

The next plugin build will support the direct rendering of the Houdini internal VDB primitive, so this kind of problems should be fixed.

Thanks,
-Juanjo