Importing vdb files sequence to Maya Arnold (mtoa)

Hi,

**We want to render vdb files using Maya Arnold.**
I'm following this tutorial https://support.solidangle.com/display/AFMUG/OpenVDB+Workflow
but instead of generating vdb files from Houdini we are using Maya 2018.3 with OpenVDB (opensource). So I found this issue https://answers.arnoldrenderer.com/questions/2515/mtoa-openvdb-sequence-file-problem.html which looks to be the same problem as mine.

I'm generating vdb files following this tutorial https://www.youtube.com/watch?v=R8Y9VqU_YTI. After that, I import these vdb files in a new scene using aiVolumeShape, and I get these warnings:

> # Warning: cannot declare constant STRING filename on aiVolumeShape - name already in use #
> # Warning: cannot declare constant ARRAY STRING grids on aiVolumeShape - name already in use #
> # Warning: cannot declare constant ARRAY STRING velocity_grids on aiVolumeShape - name already in use #
> # Warning: cannot declare constant FLOAT velocity_scale on aiVolumeShape - name already in use #
> # Warning: cannot declare constant FLOAT velocity_fps on aiVolumeShape - name already in use #
> # Warning: aiVolumeShape: could not set BOOL parameter "disable_ray_extents" #
> // Warning: [volume] RuntimeError: Expected to decompress 1228 bytes, got -1 bytes //
> // Warning: [volume] invalid grid name: "density" //
> // Warning: [volume] could not find any valid grid to export, cannot create volume //
> // Warning: aiVolumeShape: shape has empty bounding box: (3.40282347e+38 3.40282347e+38 3.40282347e+38 x -3.40282347e+38 -3.40282347e+38 -3.40282347e+38) //

It is the right way to export vdb files or could it be that Arnold does not support this feature?

Important additional info:

- Exporting/Importing vdb files using just OpenVDB nodes we are getting the results as expected, meaning that we see the simulation of volumetric data from the effects.
- We have compiled openvdb Maya plugin for Maya 2018.3 using Visual Studio 2015 for Windows 10.

Any solution Guys? or if I am doing anything wrong, please let me know.

Start with the aiVolumeShape warnings and compare the generated files against the OpenVDB Workflow and Maya 2018.3 import steps mentioned in the report. Done means determining whether the files contain a valid density grid that Arnold can read, or documenting the unsupported or incorrect part of this workflow.

Written by the indexing model from the issue text.