Release Notes

Materials - Release Notes - 2022.3.0

Material improvements


UsdPreviewSurface now supports unitless emissive texture map values. Previously, the RTX and Iray renderers assumed that map values were in Nits. Emissive units is not specified in the USD specification and in HdStorm and other renderers, the textured value is often the final exposed RGB value in the image.

In 2022.3.0 emissive values are scaled such that their value is equal to the output RGB image for our default camera Exposure

Camera Exposure







Distant Light

UsdPreviewSurface supports UsdTransform2d and UsdPrimvarReader nodes

MDL Reloading

Omniverse will now dynamically re-load changes to MDL source, updating the MDL database and re-compile the material.


Omniverse adds the base OmniPBR template model to the Material Editor. You can now map and modify inputs directly to the base material model to create custom MDL materials.

Material Editor

Authors can now add their own materials and functions to the Material Editor Node List.

MaterialX Read supports

Omniverse supports reading of .mtlx material documents.

MDL Path Resolution Changes

Summary of the changes for resolving MDL paths:

  • MDL built-in paths (i.e OmniPBR.mdl, OmniPBR_ClearCoat.mdl, OmniSurface, nvidia/aux_definitions.mdl, nvidia/core_definitions.mdl, OmniUE4Base.mdl, etc.) will no longer be anchored to their referencing layer URL (i.e omniverse://nucleus-server/some/stage.usd or https://server/some/other/stage.usd). These MDL built-in paths will still resolve correctly if they live next to the referencing layer URL but that is completely handled by the client-library and not USD

  • MDL paths not prefixed with “./” or “../” can still be anchored relative to the referencing layer if they exist and the referencing layer is a URL or file path on disk

  • MDL built-in paths are no longer considered search paths

  • MDL built-in paths are no longer considered relative paths unless prefixed with “./” or “../”

  • This behavior works through SdfAssetPath type Attributes without modifying Sdf

  • This behavior can be enabled / disabled by setting the environment variable OMNI_USD_RESOLVER_MDL_BUILTIN_BYPASS or in <APPLICATION>/kit/extscore/omni.usd.config/omni/usd_config/

  • At the moment, this resolve behavior is disabled by default by can be easily switched


UI/UX Improvements

  • New Material Editor for authoring UsdShade graphs

  • Dragging MDL materials to the Viewport opens Create Material Dialog to specify SubIdentifier material

  • Added thumbnail icons to material search box.

General improvements

  • Added standard MDL search paths. MDL defines two sets of standard search paths: User-space and System-space search paths, where User-space search paths take precedence. The search paths can be configured using the MDL_USER_PATH or MDL_SYSTEM_PATH environment variables, respectively. When specifying multiple paths, paths are separated by semicolons (on Windows) or colons (on Linux and Mac OS).

    If the environment variable is not set, the following default is used for the User-space search path:

    • %DOCUMENTS%mdl (on Windows),

    • $HOME/Documents/mdl (on Linux), and

    • $HOME/Documents/mdl (on Mac OS),

    For the System-space search path:

    • %PROGRAMDATA%NVIDIA Corporationmdl (on Windows),

    • /opt/nvidia/mdl (on Linux), and

    • /Library/Application Support/NVIDIA Corporation/mdl (on Mac OS).

    • Added a Kit configuration setting “/app/mdl/nostdpath” to disable standard MDL search paths. (default false)

    • Added a Kit configuration setting “/app/mdl/additionalUserPaths” to add additional user paths, which take precedence over the standard MDL user-space search paths. (default empty)

    • Added a Kit configuration setting “/app/mdl/additionalSystemPaths” to add additional system paths, which take precedence over the standard MDL system-space search paths. (default empty)

  • New OmniSurface materials added to core material library

  • Additional Vray to MDL improvements