Using your own OCIO config

OCIO Roles

RenderMan relies on a few OpenColorIO roles that need to be defined in your config.ocio file.

• rendering: 
  • This is the space in which all computations are done by the renderer. 
• data: 
  • An input that doesn't need to be converted because it provides numerical data (normal map, bump map, roughness map, etc). 
• srgb_linear: 
  • A linear sRGB/Rec.709 image, like an HDRI environment map. 
• srgb_texture: 
  • A non-linear sRGB image, like a JPEG, PNG, etc.
    • This role has been added to our basic linear configuration and to the Filmic-Blender configuration.
    • In ACES-1.2, this is already an alias to Utility - sRGB - Texture.

In practice, these 4 roles will be what most people need to effectively use colour-management. Still it is possible to add more role through the JSON configuration file.

JSON Configuration file

Many configurations contains a large number of color spaces, for special cases that are not related to 3D rendering. The only things that matter to 3D artists boil down to a handful of controls.

In order to provide a central configuration point, RenderMan requires a JSON configuration file to provide:

• A list of Roles/ColorSpaces available in UI controls.
• A list of aliases (shortened forms) that will be inserted in texture names to disambiguate them.
• A list of help strings that can be displayed in the UI controls.
• A set of rules for the Texture Manager to assign initial txmake settings.

File name

The JSON file's name is based on the directory containing the config.ocio file:

$RMANTREE/lib/ocio/basic/config.ocio  →  man_color_config_basic.json
$RMANTREE/lib/ocio/ACES-1.2/config.ocio  →  man_color_config_ACES-1.2.json

File location

At startup, the files in $RMANTREE/etc will always be read.

If the $RMAN_COLOR_CONFIG_DIR environment variable is defined, all files matching the man_color_config_*.json pattern in that directory will be loaded. This mechanism can be used to override stock configurations or add support for a custom OpenColorIO configuration.