Maya standins with Softimage ass files

If you want to export ASS files from Softimage and use them in Maya, all you have to do is add the SItoA shaders (eg SItoA\Application\Plugins\bin\nt-x86-64) to the Plugin Search Path

ASS files from Softimage use SItoA-specific shaders, so you need to tell Arnold where to find those SItoA shaders. For example, since SItoA 4.0, there’s a new Closure node that connects shaders like Standard Surface to color parameters.  MtoA doesn’t  have a Closure node, because MtoA took a different approach to dealing with the fact that Standard Surface returns a closure data structure, not a color.

kicking a cputime heat map


New in Arnold 5.0.2! You can press T to get a cputime heat map. From the Arnold release notes:

  • Added cputime heatmap view to kick: When using kick you can now toggle between viewing kicks default output and a cputime heatmap with the T key. The mapping of the heat map can be scaled with the [ and ] keys.

To get the cputime heat map, you have to run kick interactive (eg with the -ipr flag):

kick -ipr example.ass

How to check what mip levels are used

You can use the Arnold log to check what mip levels are used. In the Image file statistics, there’ll be a MIP-COUNT for every texture

00:00:02 124MB | Image file statistics:
00:00:02 124MB |       opens tiles MB read --redundant-- I/O time res             File
00:00:02 124MB |     1   1   538   12.6                  2.2s     8192x8192x3.f16 debug.tx MIP-COUNT[0,13,314,147,40,15,4,1,1,1,1,0,0,1]
00:00:02 124MB |

For example, with my debug texture, I see


in the Arnold log for this render:


Setting up Arnold render nodes

I’ve seen several variations of this question recently. Usually there’s some confusion about “Arnold standalone” and what’s actually required on a render node.

If you rendering scene files from Maya, or 3ds Max, or some other 3d application, then you do not need Arnold standalone.

You need the 3d application (Maya, 3ds Max) and the Arnold plugin for that application (MtoA, MAXtoA).

For example, let’s suppose you want to render Maya scene files.

  • You need to install Maya and MtoA on each render node.
  • You don’t need Maya licenses for batch rendering, and you don’t need licenses to install Maya on render nodes.
  • You need Arnold licenses, which are a separate purchase. MtoA is free and unlicensed. Arnold, however, does require a license to render without the watermark. You need one Arnold license for each render node (for you CINEMA 4D users, a TeamRender client is an Arnold render node and requires its own license).
  • You need an Autodesk network license server running somewhere (not on a render node).
  • You need to connect Arnold to the Autodesk network license manager, and you do that by setting ADSKFLEX_LICENSE_FILE.

It’s the same thing for 3ds Max and MAXtoA.

Using oiiotool and maketx to create a mipmap debug texture

To visualize the different mipmap levels, you can create a custom tx file with different textures for each mipmap level. It’s pretty easy to do with maketx. (or you can download this one)

First, to create the different mipmap levels, I use oiiotool (I use the one shipped with HtoA).

oiiotool --pattern checker:width=32:height=32:color1=1,0,1 8192x8192 3 -o 8192.tif
oiiotool --pattern checker:width=32:height=32:color1=1,0,1 8192x8192 3 -o 8192.tif
oiiotool --pattern checker:width=32:height=32:color1=1,0,0 4096x4096 3 -o 4096.tif
oiiotool --pattern checker:width=32:height=32:color1=1,.25,0 2048x2048 3 -o 2048.tif
oiiotool --pattern checker:width=32:height=32:color1=0,0,1 1024x1024 3 -o 1024.tif
oiiotool --pattern constant:color=1,1,0 512x512 3 -o 512.tif
oiiotool --pattern constant:color=0,1,1 256x256 3 -o 256.tif
oiiotool --pattern constant:color=.5,0,0 128x128 3 -o 128.tif
oiiotool --pattern constant:color=.5,.5,0 64x64 3 -o 64.tif
oiiotool --pattern constant:color=0,1,0 32x32 3 -o 32.tif
oiiotool --pattern constant:color=.5,0,.5 16x16 3 -o 16.tif
oiiotool --pattern constant:color=.82,.41,.12 8x8 3 -o 8.tif
oiiotool --pattern constant:color=0,.5,.5 4x4 3 -o 4.tif
oiiotool --pattern constant:color=0,.75,1 2x2 3 -o 2.tif
oiiotool --pattern constant:color=.5,.5,.5 1x1 3 -o 1.tif

You can’t use constant colors for all the levels, because OIIO will optimize your texture into a constant color and there won’t be any texture access.

Then I use the -mipimage flag to combine all the mipmap levels into a tx file:

maketx 8192.tif ^
-mipimage 4096.tif ^
-mipimage 2048.tif ^
-mipimage 1024.tif ^
-mipimage 512.tif ^
-mipimage 256.tif ^
-mipimage 128.tif ^
-mipimage 64.tif ^
-mipimage 32.tif ^
-mipimage 16.tif ^
-mipimage 8.tif ^
-mipimage 4.tif ^
-mipimage 2.tif ^
-mipimage 1.tif ^
-format exr -d half -o debug.tx

Here’s a couple of examples of using mip-map bias with the debug tx file.

Mip-map Bias = -1 (read a higher resolution mipmap)


Mip-map Bias = 2 (read two-levels lower resolution mipmap)



[mtoa] The case of the layeredTexture and Arnold 5 closures

In this case, the question was “why doesn’t layeredTexture work in Arnold 5?”


This is a common question/problem with Arnold 5: shaders plugged into color slots.

In Arnold 5, shaders like Standard Surface (and Lambert too) don’t return colors. So in general, you can’t plug them into color parameters. And Blinns are translated into Standard Shaders by MtoA, so you can’t plug a Blinn into a color either.

Instead of a layeredTexture, you can use a layeredShader. It knows how to handle shaders that don’t return colors. Or you could use the Arnold aiMix shader.


So, if these shaders don’t return colors, what do they return?

Closures. They return closures.

closure is not a color, it’s a bundle of data that tells Arnold how the surface (or volume) scatters light. Arnold takes care of all the ray tracing and light sampling, and then uses the closure to figure out the surface color.


From Master Zap:

“The addition of “closures” is a complete godsend. This relegates the work of rendering to the renderer, as it should be. No longer are material shaders little dumb raytracers that count lights and shoot reflection rays. A material shader returns mix of BxDF closures, and the renderer itself takes care of doing “the right thing” with them”.

From the Arnold 5 release notes:

Closures: a new closure parameter type has been added, which shaders can output instead of final colors. There are BSDF, BSSRDF, emission, matte, transparency and volume closures. See the API documentation and examples for more details on how to use these. Linking a color to a closure parameter will automatically create an emission closure with that color. A closure parameter however can’t be linked or converted to a color, as the integrator only computes lighting after shader evaluation.


[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 -- 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.