Unity USD Toolkit

Read and write OpenUSD stages from Unity at runtime, in the Editor and in built players, through Pixar's native OpenUSD 26.05 libraries.

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The Unity USD Toolkit connects Unity to OpenUSD-based simulation pipelines such as NVIDIA Isaac Sim and Omniverse. It reads and writes the same .usd, .usda, .usdc and .usdz files those tools use, with no intermediate format, so you can author a scene in Unity, open it in Isaac Sim, and bring changes back.

The package includes four key capabilities:

• Runtime export, which writes any GameObject hierarchy to USD from a running application, with UsdPreviewSurface materials, optional PNG textures, lights and cameras.
• Runtime import, which loads USD stages into GameObjects without freezing the frame, with a preview of mesh and triangle counts before you commit. UsdPreviewSurface, MaterialX and OmniPBR materials become Unity materials.
• Safe handling of untrusted files, which confines texture paths to the stage folder, checks mesh topology and caps image sizes, so you can open USD files from any source.
• USD Live Sync, a sample that streams transform changes between the Unity Editor and Isaac Sim in both directions, and the AGV Fleet LiveSync Demo built on it.

✨ New in 0.8.1:

• ✨ Animation. Time-sampled transforms, UsdSkel skeletons, blend shapes and point caches play back with UsdAnimationPlayer; UsdAnimationRecorder records Unity animation to USD.
• ✨ Physics on import. UsdPhysics becomes ArticulationBody chains, rigidbodies, colliders and physics materials, so an Isaac Sim robot moves in Unity with the same limits and drives (UsdImportOptions.ImportPhysics).
• ✨ USD composition and a stage API. References, payloads, variants and instancing survive a round trip, variants and payloads switch at runtime, and UsdStage reads and edits stages from C#.

Experimental package. com.unity.usd-toolkit is experimental. The API can change in any 0.x release, and the package is not supported for production use.

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Who this is for

Teams in automotive, manufacturing, robotics and simulation who exchange USD with tools such as NVIDIA Isaac Sim and need Unity to read and write the same stages: geometry, transform hierarchies, materials and textures, animation and robot physics.

The toolkit is not a renderer or a simulation runtime. Unity renders imported content with its own materials and render pipeline, and imported physics runs on Unity's own physics engine.

Requirements

Requirement	Detail
Unity	6.4 and newer.
Windows	x64, Windows 10 version 21H1 or later. Requires the Microsoft Visual C++ Redistributable.
macOS	Universal (x86_64 + arm64), macOS 12.0 or later.
Linux	x64, Ubuntu 22.04 or later (glibc 2.34, GLIBCXX_3.4.29).
Render pipelines	Built-in, URP and HDRP for import and export. The Runtime Demo, AGV Fleet and Reference Look samples need URP.
Git LFS	Required if you install from Git. The native libraries are stored with LFS.

Mobile, WebGL and console platforms are not supported.

Installation

1. Open Window > Package Management > Package Manager.

2. Select + > Add package from git URL.

3. Enter the following URL, then select Add:

   https://github.com/Unity-Technologies/com.unity.usd-toolkit.git
   

Add #<tag> to the URL to pin a release, for example ...usd-toolkit.git#v0.8.1-exp.1; the Releases page lists them. Don't install from Code > Download ZIP or from a release's source archive: those leave out the native libraries, which are stored with Git LFS. To install from Packages/manifest.json or a local clone, see Install the package in the manual.

Quick start

1. Install the package in a Unity 6.4 or newer project.
2. Create a script named OpenUsdStage.cs with the code below.
3. Add the component to an empty GameObject.
4. In the Inspector, set Usd Path to the absolute path of a .usd, .usda, .usdc or .usdz file.
5. Enter Play mode.

The stage appears as children of the GameObject, and the Console prints a summary. Geometry appears first and textures attach as they finish decoding; set StreamTextures = false to have ImportAsync return only when everything is loaded.

using Unity.USDToolkit;
using UnityEngine;

public class OpenUsdStage : MonoBehaviour
{
    [SerializeField] private string usdPath;

    private async void Start()
    {
        UsdImportPreviewInfo preview = UsdImporter.GetPreviewInfo(usdPath);
        Debug.Log($"{preview.MeshCount} meshes, {preview.TriangleCount} triangles, up axis {preview.UpAxis}");

        UsdImportResult result = await UsdImporter.ImportAsync(usdPath, new UsdImportOptions
        {
            Parent = transform,
            ImportMaterials = true,
            ImportTextures = true
        });

        // ImportAsync returns once the objects are built; textures keep streaming in.
        await result.TexturesReady;
        Debug.Log(result.ToString());
    }
}

To write a stage instead:

UsdExportResult result = UsdExporter.ExportGameObjectWithResult(
    exportRoot,
    System.IO.Path.Combine(Application.persistentDataPath, "scene.usda"),
    new UsdExportOptions { TransformPolicy = UsdTransformPolicy.PreserveHierarchy });

Samples

To add the samples to your project:

1. Open Window > Package Management > Package Manager.
2. Select Unity USD Toolkit, then open the Samples tab.
3. Next to Runtime Examples, Live Sync Example, Runtime Demo, AGV Fleet LiveSync Demo, Isaac Robot Physics or Reference Look, select Import.

Unity copies each sample to Assets/Samples/Unity USD Toolkit/<version>/<sample>, where you can open and edit the scenes. This works for every install method, including a Git URL, which Unity installs as a read-only package. The package doesn't compile the samples until you import them.

Export Example A runtime UI that exports the open scene to any USD format, with or without textures, as baked meshes or a preserved hierarchy.	Import Example A runtime browser that scans a folder for USD files, previews their statistics and imports them.
USD Live Sync Two-way transform sync between the Unity Editor and Isaac Sim 6.1 or a Python client.	✨ Runtime Demo A runtime app that imports several USD files, lets you move parts with a gizmo, and exports the result as a referencing layer or a flattened stage.
✨ AGV Fleet LiveSync Demo Isaac Sim simulates an AGV fleet in a factory or a generated warehouse; Unity is the operator front end over a shared USD stage. Video.	✨ Isaac Robot Physics Imports an Isaac Sim robot with its physics and compares every joint limit, drive and mass with what Isaac Sim shows; drives the joints in Play Mode.
✨ Reference Look (experimental) A URP render setup that brings an imported stage close to Isaac Sim's RTX Real-Time renderer, with a menu that imports a USD file and fits the lighting to it. Needs Unity 6.7, which is in beta; the sample stays experimental until 6.7 ships and the setup is tuned for it.

✨ marks the samples added since 0.8.0. The Export and Import examples import together as Runtime Examples; the others are separate samples. Runtime Demo needs URP, the Input System and uGUI in the project, AGV Fleet LiveSync Demo needs URP and the Input System, and Reference Look needs URP.

If you imported the samples before, delete the old copy under Assets/Samples/Unity USD Toolkit before you import them again.

Workflows

Import an Isaac Sim scene into Unity

1. Save the stage from Isaac Sim as .usd, .usda, .usdc or .usdz. Keep referenced textures in the stage's folder.
2. Call UsdImporter.GetPreviewInfo to check the mesh count, up axis and units.
3. Call UsdImporter.ImportAsync from the main thread.

The importer applies the stage's up axis and metersPerUnit to the import root, so an Isaac Sim stage, which is Z-up by default, arrives Y-up and in meters. The correction sits only on the root; vertices and every prim's local transform stay as authored. Set ApplyStageUpAxisAndUnits = false to keep the stage's own coordinates. See Up axis and units in the manual.

Export a Unity scene for Isaac Sim

1. Choose the root GameObject to export.
2. Call UsdExporter.ExportGameObjectWithResult. Set TransformPolicy = UsdTransformPolicy.PreserveHierarchy to keep the transform hierarchy, and ExportTextures = true to write PNG textures.
3. Open the result in Isaac Sim, or check it with usdchecker.

Import an Isaac Sim robot with its physics

1. Set UsdImportOptions.ImportPhysics = true (it is off by default) and import the robot's stage.
2. Each articulation arrives as an ArticulationBody chain with the joint limits, drives, masses and collision filtering the stage authors.
3. Enter Play mode: Unity's physics engine runs the robot, and you drive it through the ArticulationBody API.

The Isaac Robot Physics sample does this for a bundled arm or NVIDIA's Franka Panda and compares every value with what Isaac Sim shows. See Physics in the manual.

Round-trip a stage without flattening it

Set Composition = UsdCompositionMode.Preserve on export. An imported stage is then written as a layer over the source file that holds only what changed in Unity, and every reference, payload and variant in the source survives. Prefabs are written once and referenced, and repeated meshes become instances. On import, UsdImportOptions.VariantSelections and LoadPayloads choose what to compose, and UsdImportResult.Source switches variants and payloads at runtime. See Keep USD composition and Read and edit stages from C# in the manual.

Features

The User Manual lists every supported prim type, material and option. The table compares the toolkit with Unity's earlier USD package.

	Unity USD Toolkit	USD for Unity (com.unity.formats.usd)
Isaac Sim Live Sync	Two-way sync between the Unity Editor and Isaac Sim, with the AGV Fleet demo	Not available
Status	In active development (experimental)	Deprecated since November 2024
Unity and OpenUSD	Unity 6.4 and newer, OpenUSD 26.05	Unity 2019.4, USD 20.08; does not compile on Unity 6
Runs in	Editor and built players	Editor only
Platforms	Windows, macOS (Intel and Apple silicon), Linux	Windows, macOS Intel
Load time	About 2.7x faster on the same scene in our tests	Baseline
Textures	UDIM, EXR, packed ORM maps, streamed in after the geometry	One UV set; UDIM and MDL textures not read
Materials	UsdPreviewSurface, MaterialX and Omniverse MDL, to URP, HDRP or Built-in	Standard Shader; limited URP and HDRP
Lights	UsdLux lights and dome lights	Not supported
Animation	UsdSkel, blend shapes and point caches on import; Unity animation recorded back to USD	UsdSkel and animated meshes through Timeline; no blend shapes
Physics	UsdPhysics to ArticulationBody chains, rigidbodies and colliders	Not supported
Composition	References, payloads and variants kept through a round trip; variants switched at runtime; UsdStage C# API	Variant selection and payload loading in the Editor
Other formats	Alembic .abc, Draco .drc	USD only

Not supported yet: physics on export, subdivision surfaces (imported as their control cage), point caches whose topology changes over time, MDL materials other than OmniPBR, OmniSurface and OmniGlass, materials in Alembic files, and Draco on Windows.

Architecture

The package has three layers. Only the C# API is public.

1. C# API (Unity.USDToolkit): UsdExporter, UsdImporter and UsdLibraryScanner convert between Unity objects and USD data.
2. Native plugin (UnityUSDToolkitNative): a C++ library that wraps the OpenUSD API behind a small C interface, called through P/Invoke. Each release ships the plugin for Windows, macOS and Linux; the package loads one from 0.8.0 or newer and switches features on by the release the plugin comes from (see Native plugin versions in the manual).
3. OpenUSD 26.05: Pixar's OpenUSD libraries and oneTBB, built for each platform and shipped in Runtime/Plugins.

flowchart TB
    subgraph Unity["Unity application (Editor or player)"]
        App["Your C# code"]
        API["Unity.USDToolkit<br/>UsdExporter · UsdImporter · UsdLibraryScanner"]
    end
    subgraph Shim["UnityUSDToolkitNative"]
        CABI["C interface"]
        Cpp["C++ wrapper over the OpenUSD API"]
    end
    subgraph OpenUSD["Pixar OpenUSD 26.05"]
        Lib["OpenUSD libraries + oneTBB"]
    end
    Files[(".usd / .usda / .usdc / .usdz / .abc / .drc")]

    App --> API -->|P/Invoke| CABI --> Cpp --> Lib
    Lib <--> Files

Loading

The package does not depend on com.unity.formats.usd, com.unity.importer.usd, com.unity.exporter.usd, com.unity.usd.core or USD.NET.

Documentation

Document	Contents
User Manual	Export and import options, threading, materials, animation, physics, untrusted file handling, standalone builds, troubleshooting and the API reference.
User Manual (Korean)	The same manual in Korean.
Live Sync Example	Setup, wire protocol, ownership, coordinate conversion and security.
AGV Fleet LiveSync Demo	The fleet demo: Isaac Sim side, Unity side, the shared stage and the hub.
Runtime Demo, Isaac Robot Physics, Reference Look	Each sample's own guide.
Isaac Sim client	The Kit extension, launchers and troubleshooting.
Changelog	Release history.

Troubleshooting

Symptom	Cause	Solution
DllNotFoundException	The native libraries are missing or are still Git LFS pointer files, for example after a ZIP download.	Install from the git URL, or run git lfs pull in a clone.
An imported robot has no ArticulationBody	ImportPhysics is off by default.	Set UsdImportOptions.ImportPhysics = true, and check UsdImportResult.PhysicsNotes.

Black surfaces in Isaac Sim, flat materials right after import, missing textures, batch-mode export and player builds are covered in Troubleshooting in the User Manual.

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Support

Report bugs and request features through GitHub Issues. The issue template asks for the USD file that shows the problem; most reports cannot be reproduced without it. This repository doesn't accept external contributions.

License

Unity USD Toolkit Package © 2026 Unity Technologies. Licensed under the Unity Companion License for Unity-dependent projects. See LICENSE.md.

Third-party components redistributed with the package remain licensed under their own terms. See Third-party notices.

This package does not include or redistribute any NVIDIA software. NVIDIA Isaac Sim and NVIDIA Omniverse are licensed to you by NVIDIA under NVIDIA's own terms.

Third Party Product disclaimer

The following concerns a product or service (each a "Third Party Product") that is not developed, owned, or operated by Unity. This information may not be up-to-date or complete, and is provided to you for your information and convenience only. Your access and use of any Third Party Product is governed solely by the terms and conditions of such Third Party Product. Unity makes no express or implied representations or warranties regarding such Third Party Products, and will not be responsible or liable, directly or indirectly, for any actual or alleged damage or loss arising from your use thereof (including damage or loss arising from any content, advertising, products or other materials on or available from the provider of any Third Party Products).

Trademarks

NVIDIA, NVIDIA Isaac Sim, and NVIDIA Omniverse are trademarks and/or registered trademarks of NVIDIA Corporation in the U.S. and other countries. Universal Scene Description (USD), OpenUSD, and Pixar are trademarks and/or registered trademarks of Pixar in the U.S. and other countries. Intel and oneAPI are trademarks of Intel Corporation or its subsidiaries. Microsoft, Windows, and Visual C++ are trademarks of the Microsoft group of companies. macOS is a trademark of Apple Inc. Unity, the Unity logo, and other Unity trademarks are trademarks or registered trademarks of Unity Technologies or its affiliates in the U.S. and elsewhere. All other trademarks are the property of their respective owners. Use of a third-party name or mark in this package is for identification only and does not imply any endorsement, sponsorship, or affiliation.