Blender

Overview

App or Connector?

Blender is an open source, world class 3d Modeling application and is available in omniverse Launcher. There you can download compatible versions of Blender with Connect capabilities included. The goal is to eventually move to a proper Blender Connector, but this allows blender users to have solid import/export capabilities with Omniverse and it is available today.

How do I learn Blender?

This documentation is In Addition To information in Blender Documentation. For any and all information regarding general Blender usage, please refer to the links below.

Blender Website Blender Support

Omniverse / Blender Manual

The main benefit the Omniverse Blender App offers over the standard Blender.org versions is the inclusion of a variety of USD import and export options along with NVIDIA MDL materials and support.

Importing USD Files

In the Blender File Menu under Import, Users can now select Import USD

USD Import

Option	Result
Import Cameras	Include Camera Prims in the Import.
Import Curves	Include Curve Based Prims in the Import.
Import Lights	Include Light Prims in the Import.
Import Materials	Include Material Data in the Import.
Import Meshes	Include Mesh Data in the Import.
Import Volumes	Include Volume Data in the Import.
Path Mask	Import only the subset of the USD scene rooted at the given primitive.
Global Scale	Value by which to scale the imported objects with respect to the world’s origin.
Apply Unit Conversion Scale	Scale to convert to Scene Units to Blender Units (meters).
UV Coordinates	Check to Read or Uncheck to Ignore UV’s within the Imported File.
Vertex Colors	Check to Vertex Colors or Uncheck to Ignore UV’s within the Imported File.
Import Instance Proxies	Create unique Blender objects for USD Instances.
Visible Primitives Only	If checked will not import invisible USD Prims. Only applies to primitives with a non-animated visibility attribute. Primitives with animated visibility will always be imported.”
Subdivision	Create subdivision surface modifiers based on the USD SubdivisionScheme attribute.
Guide	Include primitives with purpose “guide”.
Proxy	Include primitives with purpose “proxy”.
Render	Include primitives with purpose “render”.
Set Frame Range	Update Blender Scene start and end frame to match the incoming USD start and end frame.
Relative Path	Use relative paths from the blender file to the usd file.
Create Collection	Add all imported objects to a collection.
Light Intensity Scale	Global Multiplier for Light Intensity.
Convert Light Units from Nits	Converts light intensity values from Nits to Blender Light Units.
Scale Light Radius	Apply scene scale factor (Global Scale/Unit Conversion Scale) to the radius of Spot/Local lights.
Create Background Shader	Import USD dome lights to world background shaders.
Material Name Collision	Behavior when the name of an imported material conflicts with an existing material. Modify: Create a unique name for the imported material. Skip: Keep the existing material and discard the imported material.
Import Attributes	Behavior when importing USD attributes as Blender custom properties. Supported types are ints, floats, doubles and strings. USD vectors are converted to Blender arrays of the corresponding size. None: Do not import attributes. 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.
Instancing	Import USD scenegraph instances as Blender collection instances. Note that point instancers are not yet handled by this option.
Import Shaders	Specify the type of USD shader to convert to Blender Principled BSDF shader networks.
Set Material Blend	If the Import Shaders option is set to a valid type, the material blend method will automatically be set based on the USD shader’s opacity and opacityThreshold settings.

Actions

Option	Result
Import USD	Imports the USD file with the options selected.
Cancel	Closes the Import Dialogue and Cancels the Operation.

Exporting USD Files

In the Blender File Menu under Export, Users can now select Export USD

Ref #	Link
1	USD Export
2	Attributes
3	Cycles Settings
4	Mesh Settings
5	Primitive Types
6	Stage Options
7	Conversions
8	Textures
9	Experimental
10	Actions

USD Export

Option	Result
Use Settings for	Determines visibility of objects, modifier settings, and other areas where there are different settings for viewport and rendering.
Apply Subdiv	When checked, subdivision modifiers will be used for mesh evaluation.
Author Blender Name	When checked, custom userProperties will be authored to allow a round trip.
Selection Only	Only selected objects are exported. Unselected parents of selected objects are exported as empty transforms.
Visible Only	Only visible objects are exported. Invisible parents of exported objects are exported as empty transforms.
Animation	When checked, the render frame range is exported. When false, only the current frame is exported.
Export As Overs	When checked, the USD exporter will create all prims as overrides.
Merge Transform and Shape	When checked, transforms and shapes will be merged into the one prim path.
Export Custom Properties	When checked, custom properties will be exported as USD User Properties.
Export Identity Transforms	If enabled, transforms (xforms) will always author a transform operation, even if transform is identity/unit/zeroed.
Export Child Particles	When checked, the USD exporter will export child particles.
Vertex Groups As faceVarying	When enabled, vertex groups will be exported as faceVarying primvars. This takes up more disk space, and is somewhat redundant with Blender’s current authoring tools.

Attributes

Option	Result
Export Custom Properties	Export custom properties as USD User Properties. Supported property types are ints, floats, doubles and strings. Numerical arrays of size 2, 3, and 4 are exported as USD vector attributes of the corresponding dimension.
Add Properties Namespace	Add exported custom properties to the “userProperties” USD attribute namespace.

Cycles Settings

Option	Result
Override Shutter	Allows the ability to override the explicit shutter open and close attributes. When disabled, the shutter is used from cycles render settings.

Mesh Settings

Option	Result
Vertices	When checked, vertex and point data are included in the export.
Vertex Colors	When checked, all vertex colors are included in the export.
Vertex Groups	When checked, all vertex groups are included in the export.
Face Maps	When checked, all face maps are included in the export.
UV Maps	When checked, all UV maps of exported meshes are included in the export.
Normals	When checked, normals of exported meshes are included in the export.

Primitive Types

Option	Result
Transforms	Include Transform Data in the Export. If disabled, objects will be saved as prims with the identity transform.
Meshes	Include Mesh Data in the Export.
Materials	Include Material Data in the Export.
Lights	Include Lights in the Export.
Curves	Include Curve Based Shapes in Export.
Hair	Include Hair Data in the Export.
Particles	Include Particle Data in the Export.
Armatures (Experimental)	Include Armature Data in the Export. Note that USD requires that skeletons and their skinning target meshes be organized in a hierarchy of “Skeleton Root” (SkelRoot) primitives. Specifically, a skeleton and its target must share a common SkelRoot ancestor to ensure correct binding. Since armatures and meshes with armature modifiers are automatically converted to USD SkelRoots, a straightforward way to maintain a correct hierarchy is to ensure that the target mesh is parented to the armature. Alternatively, there is an experimental “Fix Skel Root” option (in the Experimental section) to automatically find a common Xform ancestor of the skeleton and its target and make that ancestor the SkelRoot. Note that this option could potentially designate the scene root as a SkelRoot, which may be inefficient, especially for large scenes. This can be avoided by grouping the armature and target mesh under an Empty object that isn’t also the scene root. Limitation: export of “bendy bones” is not currently supported.

Stage Options

Option	Result
Default Prim Path	If set, specifies the default prim in the USD.
Root Prim Path	If set, will add an Xform prim with the given path as the parent of all prims in the USD scene. Note that 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.

Note

It is HIGHLY recommended users insert a root name (e.g., /root) before all prim paths (as in the default option values). This will Help with USD Compliance and allows assets sent to omniverse to work correctly when using sent assets in other scenes. .. image:: /content/image/blender_export_stage-options_root.png

Conversions

Option	Result
Convert Orientation	When checked, the USD exporter will convert orientation axes.
Convert to Centimeters	Set the USD units to centimeters and scale the scene to convert from meters.
Export Cycles Shader	Export Cycles shader nodes to USD.
Convert to USD Preview Surfaces	When checked, the USD exporter will generate an approximate USD Preview Surface shader network. (Experimental, suitable for converting simple material graphs.)
Convert to MDL	When checked, the export to MDL materials. (This requires the Universal Material Mapping (UMM) addon to be installed.)
Light Intensity Scale	Multiplier for the intensity of exported lights.
Convert Light Units to Nits	Convert Blender’s light energy units to nits.
Scale Light Radius	Apply the scene scale factor (from unit conversion or manual scaling) to the radius size of spot and sphere lights.
Convert World Material	Convert the world material to a USD dome light. Currently works for simple materials, consisting of an environment texture connected to a background shader, with an optional vector multiply of the texture color.
Convert UV to ST	When checked, the USD exporter will convert all uv map names to use the interchangeable USD primvar name ‘st’. (Assumes one uv layout per mesh.)
Xform Ops	The type of USD transform operators to write. This specifies how transform information is represented in the USD, as one of the following options: “Scale, Rotate, Translate” components, where the rotation is given as XYZ Euler angles; “Scale, Orient, Translate” components, where the rotation is given as a quaternion; and “Matrix”, where the transform is saved as a 4 by 4 matrix.

Textures

Option	Result
Export Textures	When checked and if exporting materials, textures referenced by material nodes will be exported to a ‘textures’ directory in the same directory as the USD.
Relative Texture Paths	When checked, material texture asset paths will be saved as relative paths in the USD.

Experimental

Option	Result
Instancing	Export Blender collection instances as USD scenegraph instances. Particle systems will be exported as USD point instancers.
Fix Skel Root	If exporting armatures, attempt to automatically correct invalid USD Skeleton Root hierarchies. See the notes for the Armatures option above for more information.

Actions

Option	Result
Export USD	Exports the USD file with the options selected.
Cancel	Closes the Import Dialogue and Cancels the Operation.

Omniverse Blender Material Templates

When creating New Meshes with the intent of working with Omniverse, lossless material templates are provided in the Shading Panel and are suggested for use.

#	Option	Result	Lossless Node Adjustment
1	UV Set	Blender Mesh Connection	No
2	UV Coordinates	UV Controls	Yes
3	Texture Inputs	Texture Management	Yes
4	Parameters	Parametric Controls	Yes
5	Output	Blender Output	No
6	Information	General Help	N/A

Access the Omniverse Material

Parameter adjustment is managed through the OmniPBR Compute node.

Texture maps can be provided in the Texture Inputs Image Texture nodes.

Converting Your Existing Materials

Upon Exporting to USD, materials are, by default, converted to MDL. Once converted, users can continue to work seamlessly using the converted materials.

For any new materials added to the scene, we suggest using Omniverse Blender Material Templates however, you can work as normal and export again to convert.

Omniverse Panel

For convenience, Omniverse also ships Blender with an Add-On that can make working with Omniverse a little more convenient by way of a panel. This panel is installed into blender by default.

File Handling

Provides convenient shortcuts to the Import and Export file dialogues.

Omni Particles

In order to comply with Omniverse, Particle Systems can be converted to individual objects which in turn become valid USD Prims in Omniverse on export.

Option	Result
Delete PS After Conversion	Deletes the Blender Particle System after converting.
Keyframe Animation	Creates Keyframes for converted assets based on the host particles.
Convert	Begins the conversion on selected assets.

Material Bake

Some materials in Blender will have a hard time or will not be possible to convert to Omniverse PBR Materials. For these materials a bake routine is provided.

Option	Result
Bake All/Selected Maps	By toggling the buttons check-mark, users can bake all maps or currently selected maps.
Texture resolution	Specify the resolution of the baked texture. Larger texture sizes may take considerable time and memory to build.
New UV(s) Toggle	Check to Rebuild UV’s during the baking process.
Margin	Click-Drag to adjust Spacing of UVs
Copy Objects and Apply Bakes	Check: Apply to Bakes to a Copy of the Objects. Uncheck: Apply Directly to Original Objects
Hide Source Objects	Checked: Hides the source assets after bake is complete. Unchecked: Does NOT hide the source asset after baking is complete.
Foreground	Uses the current blender instance to bake the textures.
Background	Uses a saved version of the scene and bakes textures in background allowing continued work in blender.
Status	Allows Status to be displayed for current background render tasks.
Import Baked Objects	Once Background Bakes Complete, Use to import the baked objects into the scene.
Delete	Allows the deletion of a baked asset.
Bake	Begins the material baking process.

Convert Material

Most materials can be converted using direct mapping to OmniPBR or OmniGlass as a Base.

Option	Result
OmniPBR	Converts the selected materials to OmniPBR, Use for Opaque Surfaces.
OmniGLass	Converts the selected materials to OmniGlass, Use for Transparent/Translucent Surfaces.

Release Notes

3.1.0-usd.100.1.10

• Support UDIM textures when importing USD Preview Surface shaders.

• New “Material Name Collision” USD import option, to allow importing materials with duplicate names.

• Added default values for the “Default Prim Path”, “Root Prim Path” and “Material Prim Path” export options.

• If the “Root Prim Path” export option is set, the root path won’t be added if a Blender object matching the root name already exists.

• Now aborting with an error if the root prim, default prim and material prim path export options are not well formed USD paths, to prevent crashes when defining prims.

• Improved warning and error messages during UMM material conversion.

• Support importing USD attributes (string, int, float and vector types) as Blender custom properties.

• Property export improvements: support exporting vector types; provide options for setting the attribute namespace.

• Enable operator presets UI for USD import and export.

• Armature export improvements: fixed bugs causing skeleton bindings to fail; warning if the skinned prim and skeleton are not under a common SkelRoot; new “Fix Skel Root” experimental option to automatically correct invalid SkelRoot hierarchies.

• Importing existing USD Preview Surface shaders as a fallback if importing MDL is selected as an option but the material has no MDL shaders.

• Fixed bug preventing packed textures from being exported when exporting USD Preview Surface shaders.

• Fixed bug preventing USD Preview Surface textures from being imported in some cases.

3.0.0-usd.100.1.3

• Fix for Omniverse Launcher installer error for Blender. No functional changes to the Blender application or addons in this version.

Initial Release

Omniverse Blender App Released: 8-15-2021

Known Issues

• No support for MDL export yet