Connector Functionality#

Functionality#

Import/Open (From USD)#

Functionality

Description

Geometry

  • Static Meshes

  • Skeletal Meshes

    • Blendshapes (as Morph Targets) Introduced in 201.0

Animation

  • Audio2Face Facial Animations

  • Skeletal and Blendshape Animation Clips Introduced in 202.0

Materials

  • Preview Surfaces

  • MDL

Textures

  • UDIM/Virtual Textures Introduced in 202.0

Cameras

USD Camera attributes mapped to Cinematic cameras

Lights

  • USD Distant Light (as Directional)

  • USD Rect Light (as Rect)

  • USD Sphere Light (as Point)

  • USD Dome Light (as sky sphere mesh and sky material) Introduced in 101.1

  • USD Lights with IES Profiles Introduced in 102.6

Export (To USD)#

Functionality

Description

Geometry

  • Export to USD w/ Skeleton

  • Nanite mesh exported brute-force as geometry (Unreal Engine 5.0)

  • Static Mesh Collision data

  • Landscapes

  • Grass textures Introduced in 101.1

  • Foliage

  • Brushes

  • Text Actors

Animation

  • Skeletal Mesh animation export

  • Level Sequence Actor export (if Autoplay checked)

Materials

  • Preview Surfaces

  • MDL Export: Native translation

Cameras

  • Cinematic camera attributes mapped to USD Cameras

Lights

  • Directional Light (as USD Distant)

  • Point Light (as USD Sphere)

  • Spot Light (as USD Sphere)

  • Rect Light (as USD Rect)

Postprocess

  • Some exposure settings saved with stage export

Blueprints

  • Meshes, Lights, Cameras, SceneComponents, etc. within a Blueprint are exported as USD after the Construction Script is run

Groom Asset Introduced in 100.4

  • Meshes, Lights, Cameras, SceneComponents, etc. within a Blueprint are exported as USD after the Construction Script is run

Live Workflow#

Functionality

Description

Stage Editing

  • Actor transformations

  • Actor addition/removal

  • Receive mesh deformation from other clients

Material Syncing

  • Material assignment

  • Material Instance parameter changes

Missing Functionality & Limitations#

The Unreal Engine is vast and has many varied authoring pipelines and asset types. For now the Omniverse USD and MDL plugins are targeting a subset of those that are useful and it will continue to grow. Listed below are some of the items that are not supported, but note that this list doesn’t cover everything.

Packaging#

For now the Omniverse USD and MDL plugins are only supported in editor mode. They cannot be run in “-game” mode or used as a packaged, shipping project. If an OmniverseStageActor is used within a level it will not cook properly.

Blueprints#

Logic Run in a Blueprint is not yet translated into any sort of compute logic within USD. A Blueprint’s components are exported to USD in whatever state that they exist after the Construction Script is run. Note that if a user wishes to capture Blueprint motion as timesamples, Unreal’s Sequence Recorder may be used and then exported as USD timesamples.

Level Sequences#

Only linear keyframes are supported in the USD import/export. On export, a cubic, or any native Unreal keyframe will be translated into per-frame, linear timesamples. On import, linear USD timesamples will be imported as linear Unreal keyframes.

Materials#

When exporting unsupported material functions watch the Message Log for notifications. Not all material functions map to MDL properly, so they are often replaced with a constant value.

The Message Log shows materials with unsupported functions

These material functions are not supported (incomplete list):

  • Complicated Custom HLSL Material Expressions that use code that doesn’t align with MDL

  • Atmospheric Light Vector

  • Atmospheric Light Color

  • Atmospheric Fog Color

  • Pixel Depth

  • Scene Color

  • Camera Vector/Position

  • Object Position/Radius

  • Field of View

  • View Property

  • Light Vector

  • Bump Offset

  • Fresnel

  • IOR from texture lookup

  • Media texture sampler

  • Particle

    • Particle Color

    • Particle Direction

    • Particle MacroUV

    • Particle PositionWS

    • Particle Radius

    • Particle Random

    • Particle RelativeTime

    • Particle Size

    • Particle Speed

    • Particle SubUV

Commandlet Limitations#

  • The export commandlet will only export maps, not individual meshes or materials.

  • The export commandlet will not properly export maps with multiple levels.

  • The export commandlet must be run with the -AllowCommandletRendering flag to support text render actors and USD Preview Surface

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