Unreal Engine 4¶

Overview¶

The NVIDIA Omniverse™ Unreal Engine 4 Connector offer a simple toolkit for UE4 Users to send and live sync their model data to an Omniverse Nucleus server. This not only gives UE4 users a first class renderer through Omniverse View or Omniverse Create but also the ability to open, edit and sync with any of the Omniverse Connect applications. Now, depending on the use case, UE4 users can choose the workflows and pipelines that work best for their needs while maintaining up to date revisions for all downstream consumers of their work.

The Omniverse Unreal Engine 4 Connector plugins are an excellent way to export scene, geometry, and material content to USD and Omniverse. The MDL (Material Definition Language) plugin’s material export unlocks access to using Unreal Engine’s industry-leading material editor as one of the easiest and quickest ways to author MDL materials. Artists can use Unreal Engine’s terrain and landscape editor, and with one click can export geometry and materials straight to Omniverse, stored as a USD mesh. The plugins also support USD and MDL importing as well as live-editing of meshes, materials, and stages.

Introduction (Video)¶

Supported Versions¶

The Omniverse Unreal Connector works in the following versions of Unreal Editor.

4.25
4.26
4.27

USD and MDL in UE4¶

USD assets are used by Omniverse USD Actors, just like a Static Mesh is used by a Static Mesh Actor. MDL assets are at first identified with this Omniverse MDL icon. Once they are imported they are represented by an Unreal Material asset icon.

Note that red folders and USD/MDL assets with a lock on them identify read-only files that are located on a Omniverse Nucleus mount.

Assets Loading and Caching¶

Assets are not actually loaded and converted from Omniverse until they are used. Once loaded, the converted UE4 assets, such as textures, materials, are cached on disks. And they will be updated when necessary. Note that the Content Browser displays USD and MDL files inside the project’s /Content/Omniverse folder, but those files do not exist on disk. As assets are loaded, intermediate UE4 assets are saved to those locations, but the are purely intermediate and only aid in reload times. Do not create assets within the /Content/Omniverse folder as they could be removed from disk when these folders are cleaned.

A Note about the Epic Games USDImporter Plugin¶

In version 102.1 of the Omniverse USD Plugins the USD library was modified with prefixed library names to allow the Epic USD plugins to run together with the Omniverse plugins. Note that some export functionality (File : Export : .usd) may be impacted due to the registration order of UExporter extensions.

Usage Instructions¶

Project Settings¶

Though the default settings should be correct for most situations, you may wish to edit settings based on your use case. You may edit these settings in project settings under plugins > Omniverse.

Note

Live Edit settings can also be controlled through an Omniverse button in the Main UE4 Toolbar.

Setting	Effect
Server List	A list of Omniverse Nucleus servers that are visible in the Content Browser
Live Edit	Enable/Disable the ability to actively edit the USD that you’re connected to, in realtime. If disabled, you must save your changes to update the USD.
MDL Template Paths	Locations of the base MDLs that Unreal can use to convert materials to MDL.
Render Context	Material import/render material setting - MDL or Default (USD Preview Surface)
Open Developer Log	Show developer log messages in the editor log
Texture Compression	Enable texture compression on import (disable to speed up import)
Enable Query Collision	If enabled, meshes will have query collision enabled on import
Keep Changes During Play in Editor Session	If enabled, changes made to a USD stage in PIE will be saved and replicated in a live session

Connecting¶

To connect to an Omniverse Nucleus server, navigate to the Omniverse Icon in the top tray and select “Add Server”.

Once selected you will be brought to this connection dialogue.

After entering an Omniverse Nucleus server, click “Add to Content Browser” to continue. Once you browser into the folder in the Content Browser you may or may not be required to login using browser authentication depending on the state of your connection ticket. If connecting to a pre-2020.2 server it will login to the server using your Windows username.

Note

caption1

If a connection fails to exist for the Omniverse Unreal Engine 4 Connector Plugin, a notification will appear on the bottom right of your screen. It signifies that you do not have a current connection open to an Omniverse Nucleus.

Removing a Server¶

To remove a Omniverse Nucleus server from the Content Browser, right click on it and select “Remove Server”. This will also remove all local cached UE4 assets that were previously imported.

Live Mode¶

If enabled, Live mode allows for realtime interaction with assets you work with in UE4 through Omniverse. Be aware that when enabled changes are stored and transmitted realtime, all changes are effectively saved to the server as they happen. Live mode is automatically disabled when a USD stage is opened in the editor. This is to prevent any unwanted changes being saved to the server after opening the stage.

Live Mode	Visual Notification
Off
On

When enabling Live mode two choices are presented, to reload the stage or to save current changes before going live. If the stage is reloaded, then unsaved changes to the local stage will be lost. If local changes are saved then this could be destructive to other clients that have unsaved changes. There is no “merge changes” option, so the correct action is dependent on the user’s situation.

Note

While live editing with another Omniverse client one might notice that while UE4 is in the background edits might not appear in the editor viewport. This is because UE4 has a performance setting that uses less CPU while in the background. This setting can be disabled in the editor preferences by unchecking the “Use Less CPU when in Background”. The Omniverse USD plugin unchecks this setting the first time it is run within a project by default. caption2

Cleaning Local Assets¶

Inevitably there are sometimes issues with the intermediate files contained in the project’s /Content/Omniverse and /Content/MDL folders that represent USD and MDL assets on the server. One way to resolve these issues is to simply remove them from the disk and let the plugin recreate/rediscover them from the server. Note, if the assets are open, or have been opened, it’s possible that the editor will not be able to delete them. Also, note that cleaning these folders locally does not remove the data on the Omniverse Nucleus server(s), it removes the intermediate UE4 assets on disk.

Opening USD Files¶

Users can open and use USD files already organized and managed from an Omniverse Nucleus server within UE4. Opening USD files from local disk is not currently supported.

Once Connected, the Omniverse Unreal Engine 4 Connector Plugin lists all Omniverse Nucleus assets in UE4 Content Browser within a directory called /Omniverse. Any USD files existing within your Omniverse Nucleus can be opened, used and edited with UE4. Any edits or modification can be saved or live synced to your Omniverse Nucleus. While USD files do not get converted, Omniverse Textures and Shaders (MDL’s) are converted to native UE4 textures and materials automatically and are managed by the Omniverse-UE4 Plugin.

To find the stage in the Content Browser after it is opened, select the Omniverse/OmniverseStageActor in the World Outliner. From the Details panel select the magnifying glass to browse to the USD stage in the Content Browser.

Browsing to the USD stage in the Content Browser

Importing Audio2Face Facial Animation Introduced in 103.1¶

Omniverse Audio2Face USD facial animation curves for MetaHuman characters can be imported after they are exported using the Blendshape Conversion option from Audio2Face’s Data Conversion tab. Since the animation curves need to interact with Unreal animation assets directly, the workflow is slightly different than the rest of the USD workflow from the Omniverse Connector. The facial animation curve USDs can be imported from either local disk or Nucleus and they are saved as Animation Sequence Unreal assets. Once imported, there is no connection or mapping back to the USD file, it’s a one-time import.

If you want to import a file from local disk, right click within the Animation Sequence’s destination folder and select Import Facial Animation. If importing from Nucleus, right click on a USD from the /Omniverse folders and select Import Facial Animation.

When importing from Nucleus a dialog box will pop up requiring two bits of input:

A destination path for the Animation Sequence Unreal asset

A skeleton, the required MetaHuman skeleton is Face_Archetype_Skeleton

This Animation Sequence may now be opened in the Animation Editor or added as an animation track for the MetaHuman Face skeletal mesh. If there’s an existing Face_ControlBoard_CtrlRig track, that can be deleted.

If further edits to the Animation Sequence are required the animation can be baked to the Face Control Rig using the right click option on the Face skeletal mesh.

Control curves can be tweaked using the Face Control Rig. In this image the eyes were drawn downward using a new keyframe.

If the desire is to have all of this animation and mesh data back in USD format in Omniverse, the Sequence or Take Recorder should be used to capture a sequence. This captured sequence can then be inserted into a level and exported as USD. This is outlined in the Animation Export to Create tutorial .

Saving USD Files¶

When working in a non-live workflow changes made to a USD stage are not sent back to the Omniverse Nucleus server immediately and save must be done explicitly. To save a USD file’s changes back to the server, right click on the USD in the Content Browser and select Save to Omniverse. Note that the File menu’s Save, or the Control+S keyboard shortcut do not save the USD back to the server, they will simply save the intermediate UE4 asset, which is ineffective. When saving a file there is an option to set a checkpoint comment if the Nucleus server supports checkpoints.

Saving a USD stage to Omniverse in the Content Browser

Copying Omniverse URLs¶

To copy the Omniverse URL into the clipboard, right click on an Omniverse asset from within the /Game/Omniverse folder in the Content Browser and select Copy Omniverse URL

Copy Omniverse URL for asset into clipboard

The Omniverse USD Layers Tab¶

Omniverse USD Layers can be viewed, manipulated, and locked by opening the Omniverse Layers tab from Window menu and selecting the Omniverse Layers option.

Exporting to Omniverse (as USD and MDL)¶

Note: before trying to export anything to Omniverse, ensure that the editor has a valid connection to a Omniverse Nucleus server.

These types of assets can be exported to Omniverse as USD or MDL files by right clicking on them and choosing Omniverse Export in the Content Browser

Maps
Meshes
Materials

Actors in a level can also be exported to Omniverse as USD by right clicking on the in the World Outliner and choosing Omniverse Export

Make sure that the output folder is under the /Game/Omniverse folder, otherwise there’s no mapping back to the Omniverse Nucleus server
Meshes, lights, and cameras found inside of Blueprint actors are also exported

Export Options¶

Option	Result
Export Method	Shared organizes materials so they can be shared by many assets Modular exports a material for every asset so that assets and their materials are all self-contained
Include MDL	Export MDL materials
MDL Dependency Option	Include Dependencies - Duplicates the MDL dependencies (templates) in Destination Folder Use Core Library Dependencies - Core MDL Library templates are referenced
Destination UE4 Template Path	Destination Folder on Omniverse Nucleus for the MDL dependencies (templates) Note: A file must be selected, but only the folder is used
Texture Size	Use Texture Setting or Source as Exported Texture Size
Export Texture as DDS	Save DDS Files to Destination Path and reference them from materials (note, these cannot be reimported in UE4, this is to save GPU texture memory in Omniverse Kit)
Include USD Preview Surface	Export Preview Surfaces
Create a material overrides layer	Export a sublayer that contains all of the material reference overs for the stage. Also create USD files for each material rather than including them in the prop stages.
Export physics data	Include collision data with static meshes
USD Scenegraph Instancing	Make every referenced mesh in a stage an instance. If the stage has duplicate meshes this can greatly reduce geometric GPU memory in another renderer, but the editing workflow may be hampered.
Export as Payloads	Use Payloads instead of References in the stage
Export as Y-up axis	If checked, USD and MDL are exported with a Y-up stage up-axis rather than the default Z-up
Export Sublevels as Sublayers	If checked, levels are exported as USD sublayers and referenced in the root stage
Include invisible levels	If checked, levels that are hidden will be included in the export and marked as invisible
Export Decal Actors as planes	If checked, decal actors are exported as “floating” plane meshes offset from their base mesh
Add extra extension to exports	Stage files will be named .stage.usd, props will be named .prop.usd
Checkpoint Comment (Optional)	Set the checkpoint comment on the Nucleus server for each exported file

MDL Templates¶

The MDL Core Library is a set of MDL templates shipped with every Connect plugin. An MDL preset can simply reference the template with requiring it to be in a particular location.

Reasons to choose “Include Dependencies”
- You want all exported MDL presets to use a specific MDL template which you control and possibly modify.
- You are concerned that as the MDL templates are modified and improved over time that there might become parameter incompatibilities between the different Connect plugins
Reasons to choose “Use Core Library Dependencies”
- You want to avoid the proliferation of the MDL templates as you do many different MDL exports
- You want to use the newly updated MDL templates that ship with Omniverse Kit or other Connect plugins rather than what existed when you exported

Export USD and MDL to Local Disk¶

Maps or meshes can be exported directly to disk as USD and MDL files with the File menu’s Export All or Export Selected options. Export All will export the entire open map while Export Selected will export the selected actor from the editor viewport.

Exporting USD and MDL assets or maps to the local disk

Stages and MDL materials can also be exported from the Content Browser. Right click on the asset, select Asset Actions, then Export.

Once the File menu option is selected (or right-click-export), the file type, or “Save as type” should be set to .usd or .usda.

Select USD or USDA file type to export USD and MDL

Export Commandlet¶

The Omniverse commandlet automates the process of exporting levels to Omniverse.

Instructions: The “-AllowCommandletRendering” flag must be added to the command line if exporting Text Render actors or USD Preview Surface.

In the following example, the FooSample map from the BarProject project is exported to a local server for testing:

BarProject.uproject -run=Omniverse -AllowCommandletRendering -map=FooSample.umap -path=”/Projects/FromUE4” -user=admin -omniverse_server=localhost:3009 -log

Export Options:¶

Option	Effect
MAP	The map name (with or without) extension. Note, specify the entire path to the map (/Game/Maps/MapToExport) if the name is ambiguous
PATH	The output path on the Omniverse server path (absolute)
USD	The name of the USD file. Defaults to the Map name
USER	The user name
PASSWORD	The password (Defaults to the user name)
OMNIVERSE_SERVER	The address of the desired server

Export Flags (true/false):¶

Flag	Default State	Effect
MDL	True	Include MDL in export
MODULAR	False	Materials are exported for each asset
PREVIEWSURFACE	False	Generate preview surfaces
ADDEXTRAEXTENSION	False	Add extra extension to exported file, ie, .stage.usd, .prop.usd
COPYTEMPLATE	True	Copy templates to export directory
TEXTURESOURCE	False	Use the source texture for the texture size
VERBOSE	True (non-shipping)	Emit some messages along with the export for debugging
STATICMESHES	False	Convert Actors to StaticMeshActors
COLLISION	False	Export collision components
BEGINPLAY	True	Call BeginPlay on world to create runtime components. Default true.
TEST	False	Log operations but do not perform the export.

Multiple Maps: If you supply a ‘+’ delimited set of maps following the -map option, the maps will be exported at the path using the map name as the sub-folder and the name of the USD file.

Example:

MyProject.uproject -run=Omniverse -AllowCommandletRendering -map=Island.umap+Cavern.umap+Moon.umap -path=”/Projects/FromUE4” -user=admin -omniverse_server=ovserver.mycompany.com

Generates:

/Projects/FromUE4/Island/Island.usd
/Projects/FromUE4/Cavern/Cavern.usd
/Projects/FromUE4/Moon/Moon.usd

Supported & Unsupported Features¶

Supported¶

Import/Open (From USD)¶

Geometry
- Static Meshes
- Skeletal Meshes
Materials
- Preview Surfaces
- MDL
Animation Introduced in 100.1
- Skeletal Mesh animation
- TimeSamples (as Level Sequence Actor)
- Omniverse Audio2Face USD facial animation controls for MetaHuman characters Introduced in 103.1
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)¶

Geometry
- Export to USD w/ Skeleton
- Static Mesh Collision data
- Landscapes
- Grass textures Introduced in 101.1
- Foliage
- Brushes
- Text Actors
Animation Introduced in 100.1
- 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
- USD BasisCurves exported if OmniverseGroom plugin enabled

Live Workflow¶

Stage Editing
- Actor transformations
- Actor addition/removal
- Receive mesh deformation from other clients
Material Syncing
- Material assignment
- Material Instance parameter changes

Note: Ctrl+Z undo doesn’t function correctly and will not replicate over the live connection.

Unsupported¶

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.

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 UE4 keyframe will be translated into per-frame, linear timesamples. On import, linear USD timesamples will be imported as linear UE4 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.

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

Meshes¶

Meshes with more than 2 UV channels with materials that use Vertex Color won’t have correct materials in Omniverse Kit.

There are issues with exporting Brushes as USD meshes. The commandlet fails to export them, and when they are exported from in the Editor UI they sometimes don’t have the correct materials.

Commandlet Limitations¶

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

When a sublevel is exported by the commandlet the persistent (parent) level will also be exported along with all other sublevels.

The export commandlet doesn’t currently set the Perspective camera in the custom layer data

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

Release Notes¶

103.1 Point Release¶

Features¶

Import Audio2Face USD facial animation controls for MetaHuman characters (OM-35209)

Bug Fixes¶

Fix crash when exporting a USD mesh with null material in Y-up axis mode (OM-37433)

Checkpoint actors that are right clicked from the viewport or world outliner panel (OM-37414)

Don’t allow saving or exporting to a read-only Nucleus folder and notify the user (OM-37424)

Fix exporting mesh with the socket attachments (OM-38063)

Add OmniSurface support for material graph MDLs (OM-37830)

Fix Undo/Redo changes so they replicate over live sync (OM-16706)

Fix deleting a copy of a referenced mesh under a referenced prim (OM-39178)

Add error notification when attempting to delete an ancestral prim

Fix USD mesh actor duplication (Alt+Drag, Copy/Paste, Ctrl+W) failures (OM-38541)

Fix USD Scope loading and exporting - now acts as an unmovable actor (OM-39383)

Fix “Copy Omniverse URL” to have a correct extension “.usd” rather than “_usd” (OM-32549)

Fix remove/add Nucleus server so it works (also fixes a server disconnect) (OM-38546)

Changes¶

Support exporting DynamicParameter material expression

Add a new parameter that was added in base::file_bump_texture in MDL 1.7

Ask the user if they want to fetch changes from the server or save changes when entering live mode (OM-32236)

Override attributes instead of duplicating full props when exporting a painted mesh (OM-38566)

Clean up many of the MDL warnings that were generated from exported materials (OM-37089)

Fix uninstall/delete from the Omniverse Launcher to only remove the currently installed Connector (OM-26048)

Note: this will only work with 103.1 builds and later, previous builds will have a broken uninstall/delete

102.6 Hotfix¶

Features¶

Add IES light profile import for USD lights, export not yet supported (OM-34371)

Bug Fixes¶

Initialize static mesh render data outside of OmniverseUSD module to avoid crash (OM-36271)

Support exporting cameras created from Default Pawn and spawned actors when recorded in a sequence (OM-34197)

Also add basic support for the spring arm component as a fixed joint to suspend a camera (without any collision avoidance)

Fix MDL custom annotation by unmangling paths

Fix strange triangulation due to world normal usage in Unreal materials when exporting as MDL (OM-34110)

Reset EV100 to 0 when the luminance is 0 to prevent the post process from overexposure

Changes¶

Add support for referencing textures, materials, and USD stages with a checkpoint URL (file.png?checkpoint=2) (OM-34630)

Allow a material to load for a GeomSubset that doesn’t define the “familyName” attribute set to “materialBind” - still emit a warning

Add support for the USD Preview Surface “Transform2d” function

If USD camera focus distance is zero use the setting from post-process on import (OM-35714)

Export EXR files as 16 bit textures since they’re now supported by Create

102.5 (4.27 only) Hotfix¶

Features¶

Updated build to support 4.27.0 Release

Add support for importing the OmniSurface MDL materials (OM-34790)

Add support for exporting a material with virtual textures (OM-35721)

Changes¶

Add an export option to disable exporting Landscape Grass to reduce memory usage

Add support for exporting materials that use a Desaturation material expression node (OM-35720)

102.4 (4.27 only) Hotfix¶

Features¶

Unreal 4.27 Preview 4 editor support added (Preview 3 support dropped)

Bug Fixes¶

Fix Lerp material expression node losing inputs with a scalar parameter caused by OM-34457 (OM-35242)

102.3 Hotfix¶

Bug Fixes¶

Separate MDL functions which require MDL 1.7 to a new core template which will be imported as needed. The main Ue4Function template maintains MDL 1.6 to compatible with older Kit SDK versions (OM-35152)

This specifically addresses the issue where Machinima 2021.1 shows red materials with Unreal 102.1 and 102.2 exports

Fix a crash by adding error checking for the custom mdl function translator

Avoid repeatedly copying template MDL files when exporting materials

Changes¶

Add option to decide if exporting preview mesh as well when exporting the animation sequence (disabled by default)

Add support for HSLS exp/exp2 to MDL math functions

102.2 (4.27 only) Hotfix¶

Note, this hotfix is only for the 4.27 Preview 3 Unreal Editor. Epic Games recently updated from Preview 2 to Preview 3 and our 102.1 release isn’t compatible, so we updated it.

Features¶

Updated build to support Unreal 4.27 Preview 3 (Preview 2 is no longer supported)

Bug Fixes¶

Fix the result of MDL lerp expression when the input is constant (OM-34457)

Adjust spot and point light exporting (OM-34234)

Fix the incorrect relative texture path when exporting objects (static mesh/skeletal mesh) to local disk

Fix crash when loading transform_vector_from_tangent_to_world() and transform_vector_from_world_to_tangent() from Ue4Function mdl

Clamping the texture coordinate index if exceeding the number of texture coordinates: Omniverse MDL used the 3rd and 4th uv sets as vertex color, so out of bound coordinates will cause the issue (OM-34912)

Add notification when the filename on the Omniverse is too long (OM-31735)

Changes¶

Setting max roughness to 1.0 which is 0.3 by default in Create to match the roughness attribute of UE material (OM-34749)

Update Core material libraries to 1dcbfb85 for OmniSurface

102.1 Point Release¶

Features¶

Unreal 4.27 Preview 2 editor support added

Add an export option to create a “material override” sublayer and material references (OM-31466)

Add Omniverse Checkpoints on Save, Export, and Live Toggle (OM-31918)

The USD DLLs are prefixed to allow the NVIDIA USD plugins to be loaded at the same time as the Epic USD plugins (OM-31328)

Note that some functionality in the plugins might be impacted due to both running at the same time

Add support for http/S3 references to allow for Omniverse skies, materials, and other assets from Create (OM-31892)

Add support for importing materials generated by the MDL Material Graph in Create (OM-31608)

Bug Fixes¶

Add version control to USD DDC to prevent crashes when importing the same USD SkelMeshes with different editor versions (OM-31982)

Add MetersPerUnit stage value to DDC cache to prevent incorrect scale on importing

Fix invalid MDLs in Create when exporting using the Core library dependencies

Fix USD Domelight import material by normalizing the reflected vector to prevent scaling

Fix bounds for USD SkelMesh animation imports (EuclidVR sample)

Fix live editing material from the USD Skel which mixes with Mesh and GeomSubset

Fix importing tangent_space_normal_texture function from base module to fix normals on OmniPBR (OM-33899)

Fix check() when importing Automotive Materials Pack M_Opaque_Master (OM-33666)

Changes¶

Unreal 4.24 is no longer supported

Live Edit will automatically be disabled when opening/importing a USD stage (OM-31918)

Add support for HLSL clamp conversion to MDL clamp

Add support for importing/exporting “unpack integer as float function” (OM-30252)

Add support for converting hlsl rgb per-component operation for the variable and function to mdl (OM-30252)

Update MDL SDK to 2021.0 (344800.2052): 01 Jun 2021

Support loading specific material from the core material lib in preparation for material node graphs (OM-31608)

Omniverse Client Library update to 1.13

101.2 Hotfix¶

Features¶

Add an option to export SubLevels as USD SubLayers (OM-30422)

Add an option to export Decal Actors and Components as USD meshes (OM-10250)

Add an option to export stages as Y-up (default is Z-up) (OM-3518)

Bug Fixes¶

Fix missing USD Layer names in the Omniverse Layers tab (OM-13577)

Add a missing vector and matrix multiplication support for MDL distilling (OM-30492)

Fix installer to support a relocated Unreal Engine install from Epic Games Launcher (OM-30765)

Fix a vertex color bug on mesh export and weld USD static mesh verts

Fix Skeletal Mesh live transform update issues (OM-30696)

Fix a crash due to shared SkelMesh DDC entries between engine versions (OM-31982)

Fix an issue where imported animations replay too slowly due to usage of framesPerSecond rather than timecodesPerSecond

Prevent OmniAsset in mounts from saving and live editing (OM-31753)

Fix folders and assets missing read-only mount flags (OM-31821)

Fix a reconnect loop on disconnected Nucleus servers (OM-26381)

Changes¶

Add “localhost” as the default in the Add Omniverse Server dialog (OM-2734)

Allow “omniverse://servername” in the Add Omniverse Server dialog (OM-2734)

Add export commandlet options for payloads and layered sublevels

Export World Outliner folders as USD Scope prims (OM-30645)

Add an “Export Current Level to Omniverse” option from the menu button (OM-30627)

Add an option in the project plugin settings to save stage changes during Play in Editor sessions (OM-28372)

Update the Omniverse Client Library to 1.11.15

Notes¶

This is the last update to the Unreal Engine 4.24 Connector. Future releases will only contain Connectors for 4.25, 4.26, etc.

101.1 Point Release¶

Highlights¶

Source code included to allow source builders of Unreal Engine to use the plugin.

USD Skeletal Mesh import improvements to support more USD hierarchies

Fixed Skeletal Mesh material editing in live-sync

Added support for exporting IOR values in MDL with Unreal Ray Tracing Translucency

Fixed many custom HLSL material expression issues for MDL export

Add import and live-sync support for USD DomeLights as UE4 sky sphere actors.

Features¶

Include source code in the Launcher download to support GitHub Unreal Engine source builds

Bug Fixes¶

Materials

Fix an issue where an MDL parameter name might be redefined, causing invalid materials (OM-29128)

Fix an issue where deleting a material made in Create while in a live sync session didn’t update in Unreal (OM-28940)

Fix missing parameter annotations from parameters in material functions

Fix live editing of materials in a skeletal mesh (OM-29530)

USD importer will convert mesh from Y-up to Z-up, so cache should be changed if the up-axis is different (OM-29351)

Changes¶

Materials

Add support for Unreal’s combined material and post process volume ray tracing translucency in transparent MDLs (OM-27969)

Prevent duplicate custom expressions in exported MDLs by using a cache

Add support for radians and degrees in custom expressions in exported MDLs

Add support for mul in custom expressions in exported MDLs (OM-29276)

Support exporting additional outputs for custom expressions (OM-29276)

Support exporting additional outputs for custom expressions (OM-29276)

Support additional float4 constructors in custom expressions (OM-29276)

Unifying the material loading for USD skeletal and static meshes (OM-29351)

Add support for DistanceToNearestSurface material node when exporting MDLs by using a constant value to generate a valid material (OM-30208)

Skeletal Meshes

Reorganize the hierarchy of UsdSkelRoot to fix a missing UsdSkeleton transform, also helpful for the multiple skeletons. (OM-29351)

Old: UsdSkelRoot -> SkeletalMeshActor

New: UsdSkelRoot -> Actor and UsdSkeleton + UsdMesh -> SkeletalMeshActor

Landscapes

Export Landscape actors with a GeomSubset and MDL Preset for each Landscape component to address issues with the visibility mask (OM-29643)

Only export the Landscape visibility mask once, as opposed to once for every layer

Lights

Improve skylight when importing a USD stage (OM-27528)

Add support for importing USD DomeLights as UE4 sky sphere mesh plus a material that supports some DomeLight properties (textures, exposure, intensity, color)

100.6 Hotfix¶

Highlights¶

Significant Skeletal Mesh and Animation import and export improvements

Fix bugs to allow for easy USD timesample/animation exports of recorded sequences - makes it easy to capture dynamic Blueprint behavior as timesampled data

Further fixes to material creation live-syncing between Create and Unreal Engine

Improvements to mesh caching of USD stages, both during the editor process lifetime (mesh cache) and between editor executions (DDC) - this makes reloading a USD stage significantly faster

Added an option to export prims in a stage as Payloads rather than References.

Bug Fixes¶

Fix a USD Skeletal Mesh animation import issue where the start time was being ignored (OM-27456, OM-27454)

Fix a Skeletal Mesh export issue when morph targets are employed by using LOD RenderData instead of the LOD Model

Fix crash when loading skel root with multiple skeleton bindings as the default prim

Fix exporting Level Sequence visibility/boolean sections if there’s only one keyframe (OM-27613)

Remove live-syncing of Level Sequence changes because of performance issues

Fix exporting spawned Blueprint meshes in Level Sequences (OM-27613)

Fix exporting Level Sequence with a 3D constraint section that has an infinite range

Fix exporting a mesh component as a Xform prim when there’s no actual mesh asset assigned (OM-27790)

Fix exporting material with PrecomputedAOMask in DDS mode

Fix a material export crash when HLSL text in custom material expressions contain comments near the end of the text block.

Fix a material export/import issue where refraction was removed with using the Fresnel node (now default IOR for invalid refraction is set to 1.491 instead of 1.0)

Fix another issue where initial material creation and application on a prim in Create did not live-sync to Unreal Engine (OM-26415)

Fix attenuation radius scaling (MetersPerUnit) for spot and point lights

Fix scaling (MetersPerUnit) for USD cameras, which use fixed units, so no scaling required

Changes¶

USD Mesh Importing

Meshes are now cached by both the mesh cache and the DDC to speed the subsequent loading of unmodified USD meshes

USD Payloads and References

Add an option to export props as payloads rather than references (OM-28488)

Materials

Update MDL Core Definitions to version 2.0.0 and set the exported SDK version to 1.6

Add support for exporting sincos() HLSL function in custom material expressions (OM-27401)

Workaround HLSL usage of the SampleGrad() function in custom material expressions (OM-27401)

Support exporting HLSL vector components as left assignment in a custom expression (OM-27401)

Add support for exporting Texture2DSample UE4 material function in custom material expressions

Add support for HLSL distance in a custom material expression

Prevent MDL export errors when encountering View to World and World to View transforms and emit a warning

Update the MDL Core materials to support hair color

Add MDL display_name annotations to strip the extraneous “inputs:” from the name in Create

Add support for exporting 2D Render Targets to PNG and DDS (OM-28954)

Animation

Add support for exporting a Blueprint animation with the “Copy Pose from Mesh” graph

Note: Only attached parent is supported

Automatically export a Level Sequence if there’s only one in the level, previously “Auto Play” had to be checked

File Support

Use UTF-8 (rather than ANSI) when interacting with the Omniverse Client Library to support all possible characters from the Content Browser

Installer

Make the uninstaller silent (OM-28140)

100.5 Hotfix¶

Features¶

Add the module .Build.cs files to allow C++ source project builds using the Epic Games Launcher source

Bug Fixes¶

Materials

Unify MDL export warnings so they all appear in the same message log whether exporting to local disk or Nucleus server

Add a new way to identify if the refraction contained in material expressions can be used for MDL IOR. For example, if texture sampling is used to drive refraction attributes in a material, it will be ignored and replaced with the default IOR constant.

Fix 4.26 fog volume MDL exports, the subsurface color attribute was incorrect

Fix an issue with a missing override material when exporting instanced meshes

Fix an issue where initial material creation and application on a prim in Create did not live-sync to Unreal Engine

Fix MDL/texture importing when sampled with address mode (wrap vs. clamp)

Fix translation of the Panner material expression node to MDL

USD

Fix a crash when exporting shots in a Level Sequence that end outside the time range

Fix a crash by not allowing an imported Level Sequence actor to be renamed

Fix a crash when editing the transform of an instanceable prim by locking the movement of an actor if it’s a descendent of an instanceable prim

Fix USD warnings when reading incorrect value types

Fix an issue where USD mesh shapes axis changes did not live-sync

Lights

Fix export of SpotLights to USD SphereLights

Fix the import of SphereLights as SpotLights to take the stage’s metersPerUnit setting into account

Install

Fix the uninstall to only delete files that were installed, not the entire folder where the plugins were installed

Changes¶

Materials

Add annotation to MDL parameters so that DisplayName, Description, SortPriority, Group, and Range are all exported and visible in Create

Add support for the clamped texture sample setting in the texture asset for MDL export

Add support for the exporting the PerInstanceRandom material expression node to MDL

Other

Add a utility Blueprint function to list the contents of a Omniverse server folder (ListOmniverseFiles)

Add support for exporting Level Sequence shots with the correct priority into a single Omniverse shot camera

Support mapping a Post Process Volume’s “Exposure Compensation” to “cm^2 Factor” in the Tone Mapping RTX Settings in Create

Add support for importing USD capsule shapes

The defaultPrim on exported stages now have a blank Kind, rather than be set to “group”. This fixes some prim/defaultPrim selection issues in Create.

100.4: Hotfix¶

Features¶

Add the optional OmniverseGroom plugin to 4.25 and 4.26. This plugin will export Groom assets as USD Basis Curves.

Bug Fixes¶

Fix crash when importing Black_Oak from mounted tree library. Do not attempt to reuse an actor of a different class.

Fix a crash when closing the editor when connection to an Omniverse server had previously failed

Fix a crash when opening an MDL that is referenced from a path larger than 260 characters (or so) due to Unreal Editor path length issues

Fix a crash when exporting a Level Sequence actor with a shot in negative time

Fix USD Skeletal Mesh animation importing and playing when triggered from within a Level Sequence

Fix an issue where imported USD timesamples that changed visibility on a parent prim did not affect children meshes.

Changes¶

Make basic USD shapes (sphere, cube, etc) use the same default material that meshes use when no material is bound

Don’t allow deletes of ancestral prims from referenced USDs within a stage

Support live replacement of mesh prim from point instancer with a UE4 static mesh

Workaround issues related to materials that employ Parallax Occlusion Mapping (POM) since this doesn’t translate well to MDL

Add support for the Black-body radiation material expression node with MDL

Add primitive data (bounding box, etc) from Unreal Engine to MDLs through a custom expression

Trigger Skeletal Mesh animation from within a Level Sequence rather then on the actor to ensure that animations with other actors are synchronized.

100.3: Hotfix¶

Features¶

Add support for MetersPerUnit on import and export for meshes, shapes, cameras, lights, and stages

Bug Fixes¶

Fix crash when editing material caused by Geometry Subset material binding

Remove duplicate vertices when exporting UE4 Landscape to USD mesh

Fix SkelRoot live edit perf issue

Get full data and handle transform exporting from Level Sequence sections even if there’s no key in a shot

Avoid crashing when MDL function call creation fails and reports an error

SkyAtmosphere material expressions get a constant 0 value when exported as MDL

Changes¶

Always create UE4 actor when loading a USD prim (rather than only if it is a model or lacks a parent component). This changes the layout actors, meshes, components, etc in UE4 to be more like the USD stage. Fewer components, more actors

Merge multiple camera sequence shots into a new USD camera while still preserving the original shot cameras

Support exporting BC6H/BC7 2D textures

Replace UE4 material function DeriveTangentBasis with TangentBasis when exporting MDL materials due to the usage of incompatible DDX and DDY material nodes

100.2: Hotfix¶

Features¶

Add Unreal Engine 4.26 editor support

Note: The export folder dialogs in 4.26 do not refresh Omniverse server folders properly. Browse/create folders from the Content Browser first.

Bug Fixes¶

Collision properly exported from stand-alone static mesh asset exports

Fix crash when exporting DDS textures when a material uses virtual textures (note, proper VT export is not supported)

Fix crash when loading Level with USD actors

Fix live-edit of many Cinematic Camera properties

Fix binding materials to geometry subsets, honored only if the familyName of subset is UsdShadeTokens->materialBind

Remove the “Omniverse USD Sequence+ (usd)” Image Output Format from the Render Movie Settings because it is no longer supported

Fix crash when importing USD skeletal meshes. Garbage collection cleans up StaticMeshLOD so some classes needed to be moved to a different module.

Changes¶

Avoid exporting TangentX array for skeletal meshes if unnecessary

100.1: Point Release¶

Features¶

USD upgraded from 19.11 to 20.08

USD exports use the new USD Physics Schema

Skeletal Mesh animation import and export support added

Level Sequence actor import and export support added (as USD Time-sampled data).

USD Scenegraph Instancing export option added

Bug Fixes¶

Improve Blueprint export (for meshes, cameras, text render actors, and lights)

Fix normal generation on USD imports that contain no normals

Fix live update issues with Camera actors

Changes¶

If DDS textures are exported then they will be referenced by exported materials

Note, there’s no DDS importer so the exported textures will not import properly in UE4.

Log messages added during export to Omniverse to make it more clear when

Add option to include invisible levels when exporting

Exporting levels as USD to the file system are now organized as props and references. Previously all meshes were defined in the stage USD file.

Add an “About Plugin” dialog from the Omniverse toolbar button

2020.2: Hotfix 2¶

Bugs¶

Update Omniverse Client Library to 0.9.1064 to address file listing issues and potential data loss while overwriting large files

2020.2: Hotfix 1¶

Bugs¶

Fix a crash when running in VR Mode in the editor

Skip exporting a section if there are no faces

Update Omniverse Client Library to 0.9.723-mr2020.2.1-602740bb to fix some LFT issues

Fix a couple problems with texture exporting and importing (settings and global texture settings)

Changes¶

Improve the hierarchy of meshes under Blueprint actors when exporting. Remove an extra Xform and make them have a proper origin (not 0,0,0)

2020.2: Point Release¶

Features¶

New Omniverse Client Library

Add support for multiple Omniverse Nucleus servers connected simultaneously

References between servers supported

Add a right-click save to Omniverse option on assets when Live mode is not enabled

Bake O/R/M USD Preview Surface textures to 8-bit gray textures

For a shared asset export the MDL Schema will be a material instance based on an MDL Preset, rather than simply pointing to an MDL Preset

This reduces the number of materials in a stage export, but note that static switches will still cause distinct material creation

Bug Fixes¶

Fix a reload issue on USD stages, now it will pull the latest version from the server rather than a stale version

Fix exporting multiple text components from a Blueprint

Fix importing and exporting the relative transform of a USD prim

Fix crash when loading MDLs for the first time in a new project

Fix getting Export LOD from LandscapeStreamingProxy

Fix writing files larger than 2GB to Omniverse

Indicate that no filename is necessary when exporting multiple assets and don’t lose the default path when Cancel is hit

Use global ::anno style imports for standard MDL modules (per specificiation)

Add support for the MDL core library clearcoat and opacity base variants

Resolve UDIM path for USD Preview Surface and MDL Schema

Note that the UDIM path is resolved with the first texture only. If UV > 1 then the texture shown will be incorrect.

2020.1: Hotfix¶

Bug Fixes¶

Make sure all characters are UTF8 with MDL exports and imports

Replace engine variable with constant in custom expression during exporting

Fix distilling of MDLs that use a Fresnel function

Notify users that vertex and pixel normal expression cannot be used for MDL IOR

Fix an issue where the Omniverse texture etag was saved before a texture load was completed. This prevents random garbage materials appearing on meshes.

Avoid loading from empty USD asset path address

Support masked materials when exporting and importing USD Preview Surfaces

Support actors with the same name in multiple sublevels while exporting USD

Fix proto index if there are empty instanced mesh components

Fix separating sections to meshes: Note that the number of vertices can’t be obtained from static mesh section

Fixing baking preview surface for the dynamic translucent material instance : Dynamic material instance can’t set the parent directly

Mangle/Unmangle invalid characters to make UE4 access Omniverse path

Features¶

Use the editor’s Landscape ExportLOD property to determine what LOD to export to USD

This is useful because Landscape actors are currently exported as meshes and the size can get out of hand quickly

If MDL load fails try to load the preview surface instead (and vice versa)

Automatically disable the editor CPU throttling to avoid live editing issues

2020.1: Point Release¶

Changes¶

4.25 Support

Geometry (Static Mesh)

Switched from exporting GeomSubsets to Meshes to support Preview Surface

Multiple landscapes in one map is now supported

Better support for brush geometry export

Text Render actor export

Materials

Vertex color support added

Vertex color painting

Landscape layers

Unlit translucent material support added

Dynamic material instances are exported to a single MDL file (greatly improves rendering performance)

Precomputed AO mask support added

Texture bombing added

Many noise features added

Noise

Simplex: Perlin

Gradient: 2D texture (3D texture not supported)

Value

Vornoi

Vector Noise

Cellnoise

Perlin 3D

Perlin Gradient

Perlin Curl

Voronoi

Cameras

Perspective camera in Omniverse Kit defaults UE4 editor perspective camera transform

Lighting

Some post process settings saved to stage (exposure)

Local Workflow

Local USD/USDA export added to the File:Export menu

Physics

Export collision by default

Exporting complex, triangle mesh collision

Editor Experience

Read-only Omniverse mount icon overlay on new Omniverse USD and MDL asset icons

Versions in plugin info

More/fixed documentation

Omniverse

Live material updates and stage management bug fixes

Automation

Level export commandlet

Script to automate level export