USD Supported Features

This page provides information on the supported features with Universal Scene Description by V-Ray for Maya.

USD Rendering

The following features are supported when rendering USD files with V-Ray for Maya:

• Static meshes
• Animated transforming meshes
• Animated deforming meshes
• Motion blur for animated meshes
• Particles
• Hair
• VDB volumes referenced in USD files
• UsdPreviewSurface material
• V-Ray materials encoded in USD files
• V-Ray textures encoded in USD files
• V-Ray lights encoded in USD files
• USD light types encoded in USD files (including Maya's Spot, Direct, Point lights)
• V-Ray Displacement and Subdivision encoded in USD files¹⁴
• Local rendering of USD edits that are not saved to USD file on disc
• Bifrost USD graphs
• Animation of shader parameters

• Maya nParticles and nParticle animations⁵

• USD Skel
• Dynamic USD plugins (e.g. Golaem for USD)
• VDB shaders

• Custom V-Ray attributes with USD Utility Textures such as VRayUserScalar and VRayUserColor

• V-Ray Object Properties assigned to an object
• V-Ray Extra Attribute Object ID
• V-Ray Proxy
• VRayMaterialX
• Render Elements ¹³

Notes

13. Render Elements from USD stage can be rendered in Maya using the following post-translate script. Note that this approach is not supported with the Hydra compatible translator. Use the environment variable VRAY_USD_HYDRA_TRANSLATOR=0 to disable it.

//Render V-Ray Render Elements.

from vray.utils import * 

u = findByType('VRayScene')[0]
u.set('override_render_elements', True)

14. VRayMultiSubTex's Random by Render ID mode is inconsistent between renders. It's recommended to use other modes instead.

USD Export

The following features are supported when exporting USD files from Maya with V-Ray:

• V-Ray shaders (materials and textures). The V-Ray Plug-in Configuration needs to be selected¹
• V-Ray lights¹
• V-Ray Displacement; V-Ray Subdivision¹⁴
• V-Ray Physical Camera
• V-Ray Dome Camera. When importing a scene containing V-Ray Dome Camera, the camera is disabled by default
• Maya nParticles and nParticle animations⁵

• Custom V-Ray attributes with USD Utility Textures such as VRayUserScalar and VRayUserColor.

• V-Ray Object Properties assigned to an object
• V-Ray Extra Attribute Object ID
• V-Ray Proxy
• V-Ray Render Settings ⁸
• V-Ray Render Elements (see below for an exhaustive list)
• V-Ray materials and Material X
• Multiple UVset(s)

Exporting V-Ray materials and VRayDisplacement

Materials, including V-Ray materials, can be exported to USD using Maya's File > Export / Export Selected menu.

To export V-Ray materials to USD files without including geometry, the vrayExportUsdMaterials command can be used.

vrayExportUsdMaterials "<path/to/usdFile.usd*>"

The example above exports all materials in the scene to a USD file. This includes V-Ray materials and Maya materials supported by V-Ray like Lambert, Blinn, and usdPreviewSurface.

The vrayExportUsdMaterials command offers some additional optional flags that can be used to export VRayDisplacement and to only export the current selection:

-selection - When specified, only the selected materials are exported. Selecting a mesh will export the assigned material and its shading network without the actual mesh. The flag is used without arguments.

-displacement - Enables export of VRayDisplacement and VRaySubdivision. The flag is used without arguments.

-help – Prints out a help message in cases where there is an error with the command.

Notes

• The optional flags can be combined.
• The usd extension used in the file path string argument specifies whether a binary .usd file or an ASCII .usda is exported.
• If the command has an invalid or incorrectly used flag, a corresponding error message is printed. For a more detailed message add a -help flag to the command.
• Upon successful export, a message is printed.

// Exports all scene materials.
vrayExportUsdMaterials "<path/to/usdFile.usd*>";
 
// Exports the currently selected material(s). For selected meshes, only their assigned materials are exported, without the actual mesh.
vrayExportUsdMaterials -selection "<path/to/usdFile.usd*>;

// Exports all scene materials, including VRayDisplcament and VRaySubdivision.
vrayExportUsdMaterials -displacement "<path/to/usdFile.usd*>;

// Exports the currently selected material(s), including VRayDisplacement and VRaySubdivision.
vrayExportUsdMaterials -selection -displacement "<path/to/usdFile.usd*>;

Exporting Render Elements

The supported render elements are:

Temporary Limitations

The following features are still in development, and support for them will be added soon.

1. Exporting light textures is supported only with the "Export All" option
2. Exporting V-Ray Fur to USD from Maya
3. Limited IPR support for USD edits
4. Importing V-Ray materials applied to particle animations from USD files
5. nParticles and nParticle animations are supported with USD version 0.16.0. nParticle animations with an emitter are not visible in the viewport
6. Exporting volumes to USD files
7. Exporting a USD scene with Hair
8. Exporting render settings is supported with the exception of SettingsDecal, SettingsHair, SettingsLightLinker, SettingsRTEngine, and VRayStereoscopicSettings.
9. When exporting the ExtraTex render element with Maya Standalone, all objects in the scene are affected regardless of whether specific objects are added to the include/exclude list.
10. Instancing lights is not supported yet with Hydra translator.
11. Disabled lights are always rendered with the Hydra translator.
12. Decal is not supported.
13. IPR support is available only in Maya 2024 with USD 0.24 and later.
14. When exporting a USD scene with Displacement or Displacement and Subdivision, those properties are exported along with the shaders. Therefore, make sure that the V-Ray materials option is enabled during export, or Displacement (and Subdivision) will not be exported.