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 and optional PNG textures.
• Runtime import, which loads USD stages into GameObjects without freezing the frame, with a preview of mesh and triangle counts before you commit.
• 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 (prototype), a sample that streams transform changes between the Unity Editor and Isaac Sim 6.0.1 in both directions.

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: static geometry, transform hierarchies, materials and textures.

The toolkit is not a renderer or a simulation runtime. Unity renders imported content with its own materials and render pipeline, and the package does not author or run physics.

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.
Git LFS	Required if you install from Git. The native libraries are stored with LFS.

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
   

You can also add the package to Packages/manifest.json:

{
  "dependencies": {
    "com.unity.usd-toolkit": "https://github.com/Unity-Technologies/com.unity.usd-toolkit.git"
  }
}

To install from a local clone or a tarball from the Releases page, use + > Add package from disk or + > Add package from tarball. For a local clone, run git lfs pull first.

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.

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
        });

        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, select Import.

Unity copies the samples to Assets/Samples/Unity USD Toolkit/<version>/Runtime Examples, where you can open and edit the scenes. This works the same for every install method, including Git URLs and tarballs, which Unity installs as read-only packages. The three scenes share one UI theme, so they import together. The package doesn't compile the samples until you import them.

Sample	Scene	What it shows
Export Example	Export Example/RuntimeExportExample.unity	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	Import Example/RuntimeImportBrowser.unity	A runtime browser that scans a folder for USD files, previews their statistics and imports them.
USD Live Sync	Live Sync Example/LiveSyncExample.unity	Two-way transform sync between the Unity Editor and Isaac Sim 6.0.1 or a Python client.

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

USD Live Sync

Unity exports the scene geometry once as base_stage.usda, then streams transform changes over loopback TCP. An Omniverse Kit extension, unity.usd.livesync, mounts the stage in Isaac Sim, converts it from Y-up to Z-up, and applies the streamed transforms. Isaac Sim can send poses back, including physics-driven poses, for objects you mark as accepting remote writes.

The sample synchronizes transforms only, on a single machine. Isaac Sim is not included with this package; install it separately from NVIDIA under NVIDIA's license terms.

To try it, see the Live Sync Example guide and the Isaac Sim client guide.

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 reports the stage's up axis and metersPerUnit but doesn't apply them. Isaac Sim stages are Z-up by default, so they appear rotated in Unity's Y-up world. To correct this, import under a parent GameObject and rotate and scale that parent:

var stageRoot = new GameObject("UsdStageRoot").transform;

UsdImportResult result = await UsdImporter.ImportAsync(path, new UsdImportOptions { Parent = stageRoot });

if (result.UpAxis == "Z")
{
    stageRoot.localRotation = Quaternion.Euler(-90f, 0f, 0f); // Stage +Z becomes Unity +Y.
}

stageRoot.localScale = Vector3.one * (float)result.MetersPerUnit; // Stage units to meters.

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.

Features

	Export (UsdExporter)	Import (UsdImporter)
Formats	.usd, .usda, .usdc, .usdz (with an optional ARKit-compatible mode)	.usd, .usda, .usdc, .usdz
Geometry	Static meshes, including meshes without Read/Write Enabled	Static UsdGeomMesh, with optional MeshCollider
Transforms	Baked into mesh points, or kept as an Xform hierarchy	Every transformable prim becomes a GameObject
Materials	UsdPreviewSurface: base color, opacity, metallic, roughness, emission; one binding per submesh	UsdPreviewSurface values become URP, HDRP or Built-in materials
Textures	Albedo, normal, metallic-smoothness and emission as PNG, with UV tiling and offset	The same set, including textures inside .usdz packages
Performance		Asynchronous import, spread across frames; statistics preview before import

Not supported yet: skinned meshes, animation, variant sets, payload streaming, materials other than UsdPreviewSurface (including MaterialX), physics schemas, and automatic up-axis and unit conversion on import.

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.
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")]

    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.

Comparison with other USD packages

	Unity USD Toolkit	USD for Unity (com.unity.formats.usd)	USD Importer / Exporter (com.unity.importer.usd, com.unity.exporter.usd)
USD version	OpenUSD 26.05	USD 20.08	USD 23.02
Read / write	Import and export	Import and export	Importer: import. Exporter: export.
Runs in	Editor and built players	Editor	Editor
Platforms	Windows x64, macOS (Intel and Apple silicon)	Windows, macOS Intel	Windows, macOS, Linux

Documentation

Document	Contents
User Manual	Export and import options, threading, materials, untrusted file handling, standalone builds, troubleshooting and the API reference.
Live Sync Example	Setup, wire protocol, ownership, coordinate conversion and security.
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.	Run git lfs pull.
The surface renders black in Isaac Sim	The albedo texture is also assigned to the metallic slot.	Keep IgnoreAlbedoInMetallicSlot enabled (the default), or assign a separate metallic map.
Textures are missing after import	A texture path points outside the stage folder.	Move the textures next to the stage. For files you trust, set AllowExternalAssetPaths = true.
Exporting a mesh fails in batch mode	Meshes without Read/Write Enabled need a graphics device.	Enable Read/Write Enabled on the meshes.
The package works in the Editor but not in a player	The player targets an unsupported platform.	Build for Windows x64 or macOS.

For more, see Troubleshooting in the User Manual.

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Support

For bugs and feature requests, file a GitHub issue. Include your Unity version, platform, package version, and the output of UsdExporter.GetRuntimeInfo().

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.