Render Threads


Negative numbers are also allowed. If specifying 0 threads means use all cores on a machine, then negative numbers can mean use all but that many cores. For example, threads=-2 means use all but 2 cores, while threads=2 means only use 2 cores. This is useful when you want to leave one or two cores for other tasks. One example of this is so that Houdini can be more responsive while Arnold is rendering in the Render View.

Thread Priority

Pin Threads

Bucket Scanning

Bucket Size


Progressive AA

Plugin Path

Procedural Path

Texture Path

OSL Include Path

MPlay Session

Specify an MPlay Session label (useful with multiple workspaces).

Create Intermediate Directories

Option to create intermediate directories for output images and ASS files.

Flush SOP Cache

Flush SOP cache after each frame to reclaim memory.

Pick Material in Render View

You can use Ctrl+LMB in the Render View to pop up a panel with the material that shaded the pixel that was clicked.

Inherit Properties

Enable properties inheritance for geometry at the expense of translation time.

Parallel Node Initialization

Initialization and update of scene nodes can be multithreaded to lower the scene preparation time in complex scenes with many objects, shaders or lights.

Bucket Work Sharing

Share work among all threads for the last remaining buckets.

Abort On Error

Abort On License Fail

Render with Watermarks (Skip License Check)

Color Management

Auto Color Space

You can set the input color space or the output driver's color space to auto.  If you do this, Arnold will use whatever you have set in the Auto Color Space option. 

Rendering Color Space

Using specific implementations of a color manager it is possible to specify Arnold's rendering color space. Arnold's default rendering color space is Linear sRGB. For other color spaces, Arnold will try to auto-detect chromaticities and illuminant, and will expect all data (textures and .ass file parameters) in that same color space. An important note is that different rendering color spaces will yield different render results when compared with the default sRGB linear. These color and intensity shifts will be more visible with transmission, but will also affect illumination and subsurface. Because of this, shader adjustments and texturing should happen in the same color space as the rendering one. 

You must set the OCIO environment variable to the config.ocio color profile path before starting Houdini. Houdini will then pick up the color spaces in the config and make them available as options for rendering color space, texture input color space and driver output color space.




Pepe model by Daniel M. Lara (Pepeland).