The valence of a vertex is the number of edges connected to that vertex. In Arnold, the maximum valence is 255 (that’s because of the data type we use to store the valence; we minimize the memory requirements since this is stored per-vertex).
If a mesh in the scene has a vertex with more than 255 edges, you’ll get a WARNING like this:
[polymesh] example_mesh: mesh has at least a vertex with valence higher than 255, disabling subdivision
But if the adaptive subdivision results in a vertex with too many edges, you’ll get an ERROR:
ERROR: [arnold] [subdiv] example_mesh: edge (144578,287741) in face 263433 has a vertex that exceeded the max valence limit of 255
If the MtoA plug-in does not load and you get a “The specified procedure could not be found” error like this:
// Error: line 1: Unable to dynamically load : C:/solidangle/mtoadeploy/2016/plug-ins/mtoa.mll
The specified procedure could not be found.
// Error: line 1: The specified procedure could not be found.
then there’s a few basic things you need to check first.
Does your processor support SSE4.1?
Support for SSE4.1 is a minimum requirement. You won’t be able to load MtoA or use Arnold if your processor doesn’t support SSE4.1.
Check the environment in Maya
For example, does the PATH include any older versions of MtoA? If you’re on Windows, run the MEL command system(“set”) to get the environment. On OSX or Linux, run system(“printenv”).
Look for any environment variable that has an Arnold or MtoA folder in it. For example, on Windows, you should not have any MtoA bin folders in PATH.
Get a Process Monitor log
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: