User Manual

Omniverse’s version of Blender is different from the standard Blender versions. The main benefits of Omniverse’s version are that it includes:

• A variety of USD import and export options

• NVIDIA MDL materials and support

Note

The following sections on importing and exporting USD files from the main File menu apply to reading and writing assets on the local file system (or on a virtual file system, such as Omniverse Drive). To access assets directly on the Omniverse servers, please use the Import USD and Export USD options provided by the Nucleus Connector add-on.

Importing USD Files

To import USD files with Omniverse’s version of Blender, navigate to File > Import > Universal Scene Description:

During import, you can configure what to include:

Ref #	Link
1	General
2	Import Types
3	Geometry
4	Materials
5	Textures
6	Lights
7	Rigging
8	Animation
9	Particles and Instancing

General

Option	Description
Visible Primitives Only	Ignores invisible USD primitives (This only applies to prims with a non-animated visibility attribute. Prims with animated visibility are always imported.)
Defined Primitives Only	Import only defined primitives. This option can be disabled to allow importing primitive overrides.
Create Collection	Adds all imported objects to a collection
Relative Path	Uses relative paths from the Blender file to the USD file
Apply Unit Conversion Scale	Scales to convert scene units to Blender units (meters)
Scale	Scales the imported objects with respect to the world’s origin
Import Attributes	Determines the behavior when importing USD attributes as Blender custom properties: None: Do not import attributes (Default) User: Import attributes in the userProperties namespace as Blender custom properties. The namespace will be stripped from the property names. All Custom: Import all USD custom attributes as Blender custom properties. Namespaces will be retained in the property names. Supported types are int, float, double, and string. USD vectors are converted to Blender arrays of the corresponding size.

Import Types

Option	Description
Meshes	Imports mesh data
Curves	Imports curve-based shapes
Volumes	Imports volume objects
USD Shapes	Imports USD Shapes as Meshes
Cameras	Imports cameras
Lights	Imports lights
Materials	Imports material data

Geometry

Option	Description
UV Coordinates	Reads UV coordinates
Color Attributes	Imports color primvars as color attributes
Validate Meshes	Removes non-manifold or otherwise improper geometry from all meshes (slow operation!).
Subdivision	Creates subdivision surface modifiers based on the USD SubdivisionScheme attribute

Materials

Option	Description
Import All Materials	If enabled, imports materials in the USD file even if they’re not assigned to imported geometry.
Color Attributes	Imports color primvars as color attributes
Validate Meshes	Removes non-manifold or otherwise improper geometry from all meshes (slow operation!).
Import Subdivision Scheme	Creates subdivision surface modifiers based on the USD SubdivisionScheme attribute

Textures

Option	Description
Import Textures	Where to import textures. Packed loads the textures as Images in the current Blender file. Copy will copy the files to a local folder. None will stop textures from being imported.
Textures Directory	If you choose to import textures through a Copy, this is the folder to which the textures will be written. If the path starts with //, then the textures will be written relative to the Blender file on disk.
File Name Collision	If overwrite is chosen, textures on disk will be overwritten if they exist. If use existing is chosen, then textures on disk will not be overwritten and instead will be reused.

Lights

Option	Description
Convert Light Units from Nits	Converts light intensity values from nits to Blender Light Units
Scale Light Radius	Applies the scene scale factor, from unit conversion or global scaling, to the radius of spot and local lights
Create Background Shader	Imports USD dome lights to world background shaders
Light Intensity Scale	Multiplies light intensity

Rigging

Option	Description
Import Armatures	Import USDSkel as Blender Armatures
Blend Shapes	Import USDSkel Blend Shapes as Blender Shape Keys

Animation

Option	Description
Set Frame Range	If enabled, match the current Blender Scene’s start and end frames to those in the USD file

Particles and Instancing

Option	Description
Scene Instancing	Import USD scene graph instances as Collection Instances. If disabled, such instances will be imported as unique objects Note: This option does not apply to USD point instancers which are always imported as point clouds with point instancing geometry nodes

Actions

Option	Description
Import USD	Imports the USD file with the options selected
Cancel	Closes the import dialog and cancels the operation

Exporting USD Files

To export USD files in Omniverse’s version of Blender, navigate to File > Export > Universal Scene Description:

During export, you can configure what to include:

Ref #	Link
1	General
2	Stage
3	Export Types
4	Geometry
5	Materials
6	Lights
7	Rigging
8	Animation
9	Particles and Instancing

General

Option	Description
Use Settings for	Determines the visibility of objects, modifier settings, and other areas where there are different settings for viewport and rendering
Selection Only	Exports only the selected objects (Unselected parents of selected objects are exported as empty transforms.)
Visible Only	Exports only visible objects are exported (Invisible parents of exported objects are exported as empty transforms.)
Create ARKit Asset	For USDZ export, flatten the entire stage as per the ARKit Asset recommendations
Convert Orientation	Converts the orientation axes
Convert to Centimeters	Converts the USD units to centimeters and scales the scene to convert from meters
Relative Paths	Export paths referenced by the USD file as relative to that file.
Export As Overs	Creates all prims as overrides
Merge Transform and Shape	Merges transforms and shapes into one prim path
Xform Ops	Specifies how transform information is represented in USD, using one of the following options: - Scale, Rotate, Translate (The rotation is given as XYZ Euler angles.) - Scale, Orient, Translate (The rotation is given as a quaternion.) - Matrix (The transform is saved as a 4x4 matrix.)

Stage

Option	Description
Default Prim Path	Specifies the default prim in the USD
Root Prim Path	Adds an Xform prim with the given path as the parent of all prims in the USD scene. Note: The given root path must not match the name of an existing root-level object in the Blender scene. If such a Blender object exists, a warning will be generated and the root prim will not be added. This is avoid redundant names in the path, such as /root/root/.
Material Prim Path	Specifies where all generated USD materials and shaders are placed in the scene
Default Prim Kind	Specifies the Kind to author on the Default Prim.

Note

We highly recommended users insert a root name (e.g., /root) before all prim paths, as in the default option values. This helps with USD compliance and allows assets sent to Omniverse to work correctly when using sent assets in other scenes:

Export Types

Option	Description
Transforms	Exports transform data (If disabled, objects will be saved as prims with the identity transform.)
Meshes	Exports mesh data
Materials	Exports material data
Lights	Exports lights
Cameras	Exports cameras
Curves	Exports curve-based shapes

Geometry

Option	Description
Apply Subdiv	Uses subdivision modifiers for mesh evaluation
Vertex Colors	Exports all vertex colors
Normals	Includes normals of exported meshes
UV Maps	Exports UV maps of exported meshes
Convert uv to st	Renames UV maps to the interchangeable USD primvar name st (If a mesh has multiple UV maps, the active UV map is renamed.)
Triangulate Meshes	Triangulate meshes on export

Materials

Option	Description
Convert to USD Preview Surface	Generates an approximate USD preview surface shader network (This is experimental and suitable for converting simple material graphs.)
Export Cycles Shaders	Exports Cycles shader nodes to USD
Convert to MDL	Converts Blender materials to MDL materials (This requires the Universal Material Map (UMM) add-on to be installed.)
Export Textures	Exports textures referenced by material nodes to a textures directory in the same directory as the USD. (This assumes materials are being exported.)
Use Original Paths	Use the original USD asset path for textures that were previously imported (e.g., textures that were downloaded to the local file system from Omniverse URIs). This option is not available when exporting textures
Overwrite Textures	Allow overwriting existing files when exporting textures
USDZ Texture Downsampling	For USDZ exports, keep textures the same size, downsample by longest edge to one of the preset sizes, or choose your own custom size

Lights

Option	Description
Light Intensity Scale	Multiplies light intensity
Convert Light Units to Nits	Converts light intensity values from Blender Light Units to nits
Scale Light Radius	Applies the scene scale factor, from unit conversion or manual scaling, to the radius of spot and sphere lights
Convert World Material	Converts the world material to a USD dome light. (This currently works for simple materials, consisting of an environment texture connected to a background shader, with an optional vector multiply of the texture color.)

Rigging

Option	Description
Armatures	Exports armatures as skeletons and meshes with armature modifiers as skinned meshes. Limitation: Export of “bendy bones” is not currently supported.
Export Shape Keys	Exports shape keys as USD blend shapes. Limitations: Export of “absolute” shape keys is not currently supported. Note: USD meshes with blend shape targets are typically bound to skeletons. Thererefore, if exporting armatures is disabled or if the Blender mesh with shape keys doesn’t have an armature modifier, the exported USD mesh will be bound to an automatically created “placeholder” skeleton with a single joint.
Only Deform Bones	Only export deform bones and their parents

Note

When the “Armatures” or “Export Shape Keys” options are enabled and a mesh has an armature modifier or shape keys, the pre-modified mesh will be exported for skinning in USD. This means that the exported skinned mesh will not have any modifiers applied, other than the armature modifier. Therefore, it may be necessary to apply modifiers (e.g., mirror or subdivision modifiers) to the mesh prior to export to get the expected results.

Note

USD requires that skeletons and their skinning target meshes be exported under a “Skeleton Root” (SkelRoot) primitive in the USD hierarchy. Specifically, a skeleton and its target must share a common SkelRoot ancestor to ensure correct binding. To help ensure that the correct SkelRoot hierarchy is maintained, the USD exporter will automatically find a common Xform ancestor of the skeleton and its target and make that ancestor the SkelRoot.

Animation

Enabling the checkbox in the header of the Animation panel will enable exporting of time-sampled animation. If this is not enabled, a USD file that mirrors the state of the scene at the current frame will be exported.

Option	Description
Start	Start frame to export
End	End frame to export
Frame Step	How often to sample. A value of 1.0 means the exporter will sample once every frame.

Particles and Instancing

Option	Description
Export Particles	Exports Blender particles
Export Hair as Curves	Export Blender Hair Objects as Curves
Export Child Particles	If enabled, all particles in a particle system or particle hair will be exported. If disabled, only parent particles / hairs will be exported.
Export as Instances	Exports Blender collection instances as USD scenegraph instances (Particle systems are exported as USD point instances.)

Actions

Option	Description
Export USD	Exports the USD file with the options selected
Cancel	Closes the export dialog and cancels the operation