Force Translate Shading Engines?


You may have noticed the Force Translate Shading Engine option in the export dialog (or in the Feature Overrides section of the Render Settings).
force_translate_shading_engine

Force Translate Shading Engines forces MtoA to export shape nodes with a shader link, like this:

polymesh
{
 ...
 shader "aiStandard1SG"
 declare mtoa_shading_groups constant ARRAY NODE
 mtoa_shading_groups "aiStandard1SG"
}

where “aiStandard1SG” is the name of a MayaShadingEngine shader node.

This allows you to keep your shapes and shaders in separate ASS files. For example, you could have one standin that loads the shapes, and a second standin that loads the shaders. As long as the shape nodes include links to the shaders, Arnold will resolve the links and render the shapes with the right shaders.

Exporting ASS files to specific locations


For the render -rt 1 command, you can specify the output ASS name in
the defaultArnoldRenderOptions.output_ass_filename attribute. For example:

set PRE_RENDER_MEL="setAttr -type \"string\" 
defaultArnoldRenderOptions.output_ass_filename 
 \"c:/Users/StephenBlair/Documents/example\";"
 
 render -s 6 -e 8 -r arnold -rt 1 -preRender %PRE_RENDER_MEL% 
 C:\projects\Support\scenes\_2016\XSI_deformed_logo.mb 

This will export ASS files named “example.ass”.

The scene should have the Frame/Animation ext set to something like
“name.#.ext”. Otherwise, if it is “name.ext” you’ll get filenames like
“example.ass.0004.ass”

output_ass_filename can have environment variables, but you have to be
careful to use forward slashes. For example:

set PRE_RENDER_MEL="setAttr -type \"string\" defaultArnoldRenderOptions.output_ass_filename \"%OUTPUT_ASS_FILENAME%\";" 
set OUTPUT_ASS_FILENAME=C:/Users/StephenBlair/Documents/example 

render -s 6 -e 8 -r arnold -rt 1 -preRender %PRE_RENDER_MEL% C:\projects\Support\scenes\_2016\XSI_deformed_logo.mb

There’s also the arnoldExportASS command, if you want to script the export.

maya -batch -file scene.mb -command "arnoldExportAss 
-f "/home/blairs/Desktop/example.ass" -mask 255 -lightLinks 1 -compressed 
 -shadowLinks 2 -cam sideShape;"

[MtoA] Getting an Arnold log


The Arnold log is important, not just for troubleshooting and getting help from us at Solid Angle, but also for understanding what’s going on when Arnold renders your scene.

To get an Arnold log:

  1. In Maya, click Render > Render Settings
  2. In the Render Using list, click Arnold Renderer
  3. Click the Diagnostics tab.
    mtoa_render_settings_diagnostics
  4. Set the Verbosity level to at least Warnings + Info
  5. Click the File check box to enable file logging (by default, the log file will be saved in the last folder you browsed to with  Maya; see Finding your log file).
  6. If you want to be absolutely sure of where to find the log file, click the folder icon beside the Filename box, and select a location for the Arnold log file.
  7. Depending on what OS you use, and how you started Maya, the log is also output to the Output Window (Windows) or to the terminal (on OSX and Linux if you started Maya from a terminal)

For batch rendering, Arnold log messages go into mayaRenderLog.

  • [Windows] %USERPROFILE%\Documents\maya\mayaRenderLog.txt
  • [OSX] ~/Library/Logs/Maya/mayaRender.log
  • [Linux] ~/maya/mayaRenderLog.txt

[MtoA] Renderman performance warning


If you have both Renderman and MtoA installed, you may see a warning that says “Arnold for Maya degrades Renderman performance.” Unless you are running a version of MtoA from 20 months ago, this performance warning is false. MtoA does not degrade Renderman performance.

This was fixed in Arnold 4.2.3.1 (fix #4393 main thread was pinned to a single core) back in January 2015.

Setting the procedural’s load_at_init parameter to true would also fix this.


There’s an Arnold error that recommends setting the load_at_init parameter, but people don’t always know where to find that in their favorite Arnold plugin.

ERROR| [proc] c4d|Arnold_Procedural: bounds supplied to procedural node are not large enough to contain the actual underlying geometry.
Replace given bounds: (-1, -1, -1) X (1, 1, 1), with: (-9.4028616, -9.43616867, -9.21633244) X (9.3304739, 9.43616867, 9.21633244).
Setting the procedural's load_at_init parameter to true would also fix this.

The load_at_init parameter controls whether the procedural (standin) is loaded during scene intialization (before rendering starts), or during rendering (when a ray hits the procedural bounding box).

By default, load_at_init is false, which means that procedural loading is deferred until render time.

And so, in MtoA, C4DtoA, and SItoA, the load_at_init parameter is exposed as Defer Standin Load, which is enabled by default. In HtoA, you have a Load At Init parameter on for the Arnold Procedural node.

[C4DtoA] Installing C4DtoA in a custom location


The C4DtoA installer puts the C4DtoA plugin in the default location: the plugins folder of the Cinema 4D install.

If you want to put C4DtoA somewhere else, like a shared network location, you can use the C4D_PLUGINS_DIR environment variable to point to your custom plugin location.

For example, on Windows I moved C4DtoA to a different drive and then set my environment like this:

set C4D_PLUGINS_DIR=F:\plugins
set PATH=F:/plugins/C4DtoA/arnold/bin;%PATH%

Note that I had to set PATH so C4D could find ai.dll, and that I had to use forward slashes (on Windows, C4D doesn’t like backslashes in the PATH and drops them).

On Windows, the C4DtoA installer puts a second copy of ai.dll in the C:\Program Files\MAXON\CINEMA 4D R17, so you’ll have to remove that ai.dll, and use PATH to point to the ai.dll in the C4DtoA arnold/bin folder.