[mtoa] Getting a Process Monitor log to troubleshoot problems loading mtoa

If a clean install of MtoA doesn’t work (and the computer does support SSE4.1), then “The specified module could not be found.” usually means there’s a missing dependency. Dependency Walker is a decent, if aging, tool for checking out dependencies, but for leaving no stone unturned, I prefer Process Monitor.

The MtoA plugin (mtoa.mll) depends on a handful of files only. Here’s the log of loaded DLLs for a working MtoA:


Here’s a quick walkthrough (no audio) of how to get a Process Monitor log:

[MAXtoA] Rendering XGen in 3ds Max


You can export an ASS file from Maya (with the XGen primitives) and then use an Arnold Procedural to load the ASS file into 3ds Max.

You need to add these two folders to the system environment variable Path:
  • C:\Program Files\Autodesk\Maya2018\plug-ins\xgen\bin
  • C:\Program Files\Autodesk\Maya2018\bin

For example, you can copy this:

C:\Program Files\Autodesk\Maya2018\plug-ins\xgen\bin;C:\Program Files\Autodesk\Maya2018\bin;

and paste it at the beginning of the current Path:


Restart 3ds Max after you do this.

Then add the MtoA procedurals folder to the Plugin Search Path:



[MtoA] cross-platform volume file names

The Arnold volume node uses the texture search path, so you don’t have to use an absolute path in the volume filename.


So if you need to set up a Maya scene so that the OpenVDB volumes work on any platform, you could put an environment variable in the Texture Search Path


Just note that support for volume filenames is still a little … rough. You can’t enter an absolute path in the aiVolume Filename box, then enter a texture search path, and expect MtoA to automatically export a relative path. That still needs to be implemented.

For now, here’s what to do:

  • When you first create the volume, load the vdb file and leave the full absolute path in the aiVolume Filename box.
  • Select the grids and set the other volume parameters.
  • Then set the texture search path and strip off the path from the volume file name (leaving just the file name).
  • Now the environment variable will control where Arnold looks for the vdb file.

The Arnold volume node also support environment variables, so you could do this:


But again, once you put the environment variable into the Filename, the path won’t be resolved inside Maya (but it will work when you render).

[mtoa] Register failed for arnoldAOVChildSelector

If you see this error in the script editor

# Error: Register failed for arnoldAOVChildSelector #

that means your preferred render layer setup is Legacy Render Layers (so MtoA fails to register something that’s used for the new Render Setup).

If you’re not using Render Setup, then you can safely ignore this error.


[MtoA] Jittering color with user data

To jitter color with user data, you need to connect an aiUserDataInt to the data input parameter, like this:


The user data is an mtoa_constant attribute on the shape.  For example, if add an extra attribute named mtoa_constant_jitterID to some shapes, then you can use aiUserDataInt to read the jitterID.

If you want to use the shapes as standins, and be able to set the jitterID in the scene, then export the shapes without the mtoa_constant_jitterID attribute. In the scene, you’ll be able to add mtoa_constant_jitterID to the aiStandin node. The aiUserDataInt node in the ASS file will use that jitterID.

[clm] product key not found (44)

The Problem

To use Autodesk licenses for Arnold when you batch render with Maya, Arnold must be registered in the Product Information file (aka the PIT file).

Normally the MtoA installer does this for you. But if you’re running Maya and MtoA from a network install, then Arnold won’t be registered in the PIT file, and you’ll see this in the Arnold log:

00:00:00 381MB WARNING | rendering with watermarks because of failed authorization:
00:00:00 381MB | [rlm] error initializing license system:
00:00:00 381MB | [rlm] * Can't read license data (-102)
00:00:00 381MB | [clm] product key not found (44)

and you’d see something like this in the Adlm.log:

337296 2017/11/03 12:29:54 Reason=Fatal error
337296 2017/11/03 12:29:54 ComputerName=WORKSTATION
337296 2017/11/03 12:29:54 OS=6.1.7601.Service Pack 1
337296 2017/11/03 12:29:54 File=AdlmIntLicense.cpp,Line=594
337296 2017/11/03 12:29:54 VendorID=6 [ADLMPIT]
337296 2017/11/03 12:29:54 VendorError=12 [The root information in Product Information Table XML file is missing]
337296 2017/11/03 12:29:54 Reason=Fatal error
337296 2017/11/03 12:29:54 ComputerName=WORKSTATION
337296 2017/11/03 12:29:54 OS=6.1.7601.Service Pack 1
337296 2017/11/03 12:29:54 File=AdlmIntLicense.cpp,Line=595
337296 2017/11/03 12:29:54 AdlmIntError=25 [The product key was not found]


MtoA includes pit/pitreg for registering Arnold in the PIT file, so you just need to run pitreg on the local machine, like this:

Succesfully added Arnold information to PIT file

Don’t do this:

cd C:\solidangle\mtoadeploy\2017\pit\

because you’ll get this error:

Failed to add Arnold information to PIT file (Error 26)


[mtoa] Running a silent install

On Windows, run the MtoA installer with the flags /S /FORCE_UNINSTALL=1


You can use /D to specify a different install location.

On Linux, use the – – silent command line flags. Note the space between “- -” and “silent”.

sudo sh MtoA- -- silent

The Linux installer will put MtoA in /opt/solidangle/mtoa/<maya version>. If you want to install in a different location, you can extract MtoA, and then set up your own script for installing MtoA.

On OSX, use the installer command:

sudo installer -pkg "MtoA-" -target /

Note that -target is a volume, not a folder.