This page provides information on the Cache Converter tool.


The cache_converter command-line utility can convert already existing .aur, Field3D or PRT cache sequences to OpenVDB sequences without simulating.

In order to render them faster with Phoenix's shader or in the V-Ray VolumeGrid, you can also convert OpenVDB or Field3D cache sequences to .aur.

Using the Cache Converter, you can also strip away unused grid channels from .aur, OpenVDB or Field3D files, while converting them to .aur or OpenVDB.


Default Path: C:\Program Files\Chaos Group\Phoenix FD\3ds Max 20xx for x64\bin\cache_converter


Mandatory Arguments

-srcfile – Specifies the input .aur, .vdb or .f3d file(s) name or pattern. You can use "####" as a frame number and the files will be treated as a sequence.

The drag-and-drop functionality can be used to convert .aur or .vdb files without opening the command line. You can drop the files on the cache_converter.exe and they will be converted and saved in the input directory.



-dstfile – Specifies the output .vdb or .aur file(s) name or pattern. You can use "####" as a frame number and the files will be treated as a sequence.

If -dstfile argument is not added, the source file folder will be used as a default output destination.

If you want to check the content of a cache file with -cacheinfo, without converting it, you won't need the -dstfile argument at the end of the command.

-help – Shows the available commands and the version of the tool.

-credits – Shows the copyright notices for the cache converter and used libraries. 

-cacheinfo – Displays the stored information about the selected cache files. 

-start – Specifies the starting frame of the sequence. If it's not provided, the tool will automatically scan the directory and find the minimal index.

-end – Specifies the end frame of the sequence. If it's not provided, the tool will automatically scan the directory and find the maximal index.

-storagequality – Allows you to choose the compression quality of Grid and Particle data when the output -dstfile is .aur. Valid values are between 8 (max compression) and 20 (lossless). If not provided, default value is 14.

-exportchannels – Allows you to choose which channels to be written to the output -dstfile. Using this option, you can strip away unused channels from the cache files, reducing their size, and also making them faster to load. If not provided, all existing channels will be written.

The available channel names in .aur caches are as follows (note that names are case-sensitive):

  • Temperature_phx
  • Smoke_phx
  • Speed_phx
  • VelocityX_phx
  • VelocityY_phx
  • VelocityZ_phx
  • ColorR_phx
  • ColorG_phx
  • ColorB_phx
  • Fuel_phx
  • WaveletEnergy_phx
  • AdvectionOriginX_phx
  • AdvectionOriginY_phx
  • AdvectionOriginZ_phx
  • WaveletU_phx
  • WaveletV_phx
  • WaveletW_phx
  • Viscosity_phx
  • TexU_phx
  • TexV_phx
  • TexW_phx

You can also use these aliases for the 3 components of vector channels:

  • VelocityXYZ_phx
  • ColorRGB_phx
  • AdvectionOriginXYZ_phx
  • WaveletUVW_phx
  • TexUVW_phx

-removegridch – Allows you to remove grid channels from the source cache when writing the output. If no channels are listed, all channels are removed.

-removeprt – Allows you to remove channels from a particle system when writing the output. If no channels are provided, the entire system is removed. If no system name is given, all particles are removed. This command can be repeated for different particle systems.

-gridresscale – Decrease or increase the grid resolution of the cache files. Values below 1.0 decrease the resolution, while values above 1.0 increase it. Please use a dot as the decimal symbol (e.g. 0.5 / 1.1 / 2.4 etc.). The provided number scales the number of voxels per each axis, so of you use "-gridresscale 2.0", this will increase twice the voxels along the X axis, the Y axis and the Z axis, resulting in 8 times more voxels.

-silent – Don't show messages with the conversion progress.


  • cache_converter.exe -srcfile ND2_PhoenixFDFire001_####.aur – Converts all of the cache files matching the given name. 

  • cache_converter.exe -srcfile ND2_PhoenixFDFire001_####.aur -dstfile outFile_####.vdb -start 0 -end 10  Converts the specified range of cache files matching the given name.

  • cache_converter.exe -srcfile ND2_PhoenixFDFire001_####.aur -dstfile outFile_####.vdb -start 0 -end 10 -storagequality 14 -exportchannels Smoke_phx VelocityXYZ_phx -silent – Converts the specified range of cache files matching the given name, and saves only the Smoke and Velocity channels. All other available channels will not be written to the OpenVDB cache.

  • cache_converter.exe -srcfile ND2_PhoenixFDFire002_####.aur -dstfile outFile_####.vdb -removegridch Viscosity_phx VelocityXYZ_phx -removeprt Mist Age_phx -removeprt WetMap  Converts all cache files matching the given name, and removes the Viscosity and Velocity grid channels, and the Age channel for the Mist particle system, and the WetMap particle system. All other available channels will be written to the OpenVDB cache.

  • cache_converter.exe -srcfile ND2_PhoenixFDFire001_####.aur -cacheinfo  Displays the content of the selected cache files.

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