USDZ

USDZ
Information
Type	3D file format
Industry	Augmented Reality, Virtual Reality, 3D Graphics, Mobile Computing, E-commerce
Developer	Apple Inc. and Pixar Animation Studios
Written In	Based on Universal Scene Description (USD), C++ reference libraries
Operating System	iOS 12+, iPadOS, macOS, visionOS, Cross-platform (via third-party tools)
License	Apache License 2.0 (reference implementation)
Supported Devices	iPhone, iPad, Mac, Apple Vision Pro, Windows, Linux (via tools)
Release Date	June 4, 2018
Website	OpenUSD / Apple AR Developer

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USDZ (pronounced "U-S-D-Z", Universal Scene Description Zipped) is a file format for storing and sharing 3D models and augmented reality (AR) content, developed through a collaboration between Apple Inc. and Pixar Animation Studios. Announced at Apple's Worldwide Developers Conference (WWDC) in June 2018, USDZ is specifically optimized for Apple's ecosystem and serves as the primary format for AR experiences on iOS devices. The format is registered with IANA under the MIME type model/vnd.usdz+zip.

Overview

USDZ is a zero-compression, unencrypted ZIP archive that packages Universal Scene Description (USD) files along with their associated assets such as textures, materials, and audio files into a single, easily shareable package. The format is designed to enable "direct consumption" of 3D content without requiring extraction or additional heap storage allocation, making it particularly suitable for mobile devices with limited resources.

The "Z" in USDZ stands for "zipped," distinguishing it from standard USD files by its packaged nature. Unlike traditional compressed archives, USDZ files maintain zero compression to allow for efficient memory mapping and direct access to contained data.

History

Timeline

• 2018 – Initial release: Apple and Pixar unveiled USDZ during the WWDC 2018 keynote on June 4, positioning it as a "portable, open" format for AR on iOS 12.
• 2019 – Creative Cloud adoption: Adobe announced beta support for USDZ across Creative Cloud apps, previewed in Adobe Aero. Apple highlighted growing use by companies like Target, Home Depot, and Wayfair.
• 2020 – Reality Converter beta: Apple released the free Reality Converter macOS utility to convert OBJ, glTF, and USD into USDZ.
• 2023 – Industry standardization: Pixar, Apple, Adobe, Autodesk, and NVIDIA formed the Alliance for OpenUSD (AOUSD) to further standardize and promote USD technologies, including USDZ. Blender 4.0+ added native USDZ export alongside full USD I/O.

Technical Specifications

File Structure

A USDZ file is structured as an uncompressed ZIP archive with specific requirements:

Property	Specification
Compression	Zero compression (store method only, compression method 0)
Encryption	None
Archive Format	Standard ZIP with container headers
Byte Alignment	Data for each file begins at 64-byte multiple from package start
First File Requirement	Must be .usda, .usdc, or .usd (Default Layer)
Package Type	Read-only container
MIME Type	model/vnd.usdz+zip

Typical Layout Example

Spaceship.usdz
├── root.usda
├── Textures/
│   ├── albedo.png
│   ├── normal.png
│   └── metallicRoughness.png
└── Sounds/
    └── engine.wav

Supported File Types

USDZ packages can only contain file types that can be consumed by the USD runtime via memory mapping, pointer to memory, or thread-safe file access:

3D Scene Files

• .usda (USD ASCII format)
• .usdc (USD binary format)
• .usd (USD files)

Image Formats

• PNG
• JPEG (all common extensions, 8K maximum for AR)
• OpenEXR
• AVIF (AV1 Image File Format)

Audio Formats

• M4A (preferred)
• MP3
• WAV

Technical Requirements

The format enforces several technical constraints to ensure optimal performance on mobile devices:

• Files must be accessible without unpacking the archive
• Data must be aligned on 8-byte boundaries for zero-copy access
• No compression is applied to maintain direct memory access capabilities
• The first file in the package enables progressive loading scenarios
• AR-centric constraints forbid absolute paths and embedded scripts
• Physically Based Rendering (PBR) uses USD Preview Surface shader with metallic-roughness workflow

Features

Single-File Convenience

USDZ simplifies sharing via Messages, Mail, web, or AirDrop, making it ideal for consumer-facing AR applications.

AR Quick Look Integration

USDZ files are natively supported by Apple's AR Quick Look viewer, which is integrated into the operating system. This allows users to view 3D models and place them in their real-world environment without downloading additional applications.

Progressive Loading and Streaming

The format supports various streaming scenarios through its file ordering mechanism:

• Level of Detail (LOD) streaming with low-complexity geometry loading first
• Progressive material loading with simple materials followed by textured versions
• Animation streaming with static poses loading before animated sequences
• In-place streaming where AR Quick Look and RealityKit mmap the archive

Animation and Interactivity

• Supports skeletal animation and vertex blendshapes inherited from USD
• Time-sampled transforms and skinning
• Basic gesture recognition (move, rotate, scale)
• Custom actions through Quick Look API
• Apple Pay integration for e-commerce applications
• Optional spatial audio for synchronized playback

Applications

E-commerce

USDZ has become particularly popular in e-commerce applications, with Shopify reporting significant engagement uplifts when 3D models are attached to products:

• View products in AR before purchasing
• Place furniture and home goods in actual living spaces
• Examine product details from all angles
• "Try-before-you-buy" experiences

Education

Educational institutions use USDZ for:

• Interactive 3D models in digital textbooks
• Virtual field trips
• Scientific visualization
• Historical artifact exploration

Architecture and Design

Professionals in architecture and design utilize USDZ for:

• Client presentations
• Building Information Modeling (BIM) visualization
• Interior design planning
• On-site architectural visualization

Publishing and Media

News outlets embed interactive objects in web articles using the `<model-viewer>` polyfill with USDZ fallback. Major search engines display "View in AR" buttons from schema.org model markup (iOS only).

Software Support

Creation and Editing Tools

Software	Platform	Import	Export	Notes
Reality Composer	iOS, iPadOS, macOS	Yes	Yes	Native USDZ export with animations and behaviors
Reality Converter	macOS	Yes	Yes	Drag-and-drop converter for OBJ, glTF, & USD
Blender 4.0+	Cross-platform	Yes	Yes	Native USDZ export via USD with ARKit Asset toggle
Cinema 4D	Cross-platform	Yes	Yes	Native export via USD with Zipped flag
Adobe Creative Cloud	Cross-platform	Yes	Limited	Built-in support announced at WWDC 2018
Adobe Aero	iOS, macOS	Yes	Limited	Imports USDZ for interactive AR scenes
Autodesk Maya	Cross-platform	Yes	Yes	Via Pixar RenderMan plugin
Autodesk 3ds Max 2022+	Windows	Yes	Yes	USDZ export support
Sketchfab	Web-based	Yes	Yes	USDZ download option
Unity	Cross-platform	Yes	Experimental	Via USD Unity SDK
Unreal Engine 4.27+	Cross-platform	Yes	Yes	USD Stage Editor and Python USD tools
SceneKit	Apple platforms	Yes	Yes	Framework for creating 3D games and apps
SimSoft Composer	Cross-platform	Yes	Yes	Exports to USDZ from various CAD programs
Houdini	Cross-platform	Yes	Yes	Full USD/USDZ support
Vectary	Web-based	Yes	Yes	Browser-based 3D design tool

Viewing Applications

Application	Platform	Function
Quick Look	iOS/iPadOS/macOS/visionOS	Native AR preview on Apple devices
Safari	iOS/macOS/visionOS	Web-based AR viewing
Messages	iOS/iPadOS/macOS	Direct sharing and viewing
Mail	iOS/iPadOS/macOS	Email attachment viewing
News	iOS/iPadOS	Embedded AR content in articles
Files	iOS/iPadOS	File system preview

Conversion Tools

• usdz_converter: Command-line tool included with Xcode for converting OBJ, Alembic ABC, and USDA files
• Pixar USD tools: Python-based conversion utilities including usdzip
• Reality Converter: Free macOS GUI application
• Various online converters for format transformation

Comparison with Other Formats

USDZ vs USD

Feature	USD	USDZ
Format Type	Scene description	Packaged archive
Compression	Variable	Zero compression
Platform Support	Cross-platform	Optimized for Apple devices
File Extension	.usd, .usda, .usdc	.usdz
Asset Inclusion	External references	Self-contained package
Editability	Directly editable	Read-only (must unpack to edit)
Use Case	Professional 3D workflows	Mobile AR distribution

USDZ vs glTF

Feature	USDZ	glTF
Container type	Zero-compression ZIP with multiple assets	Binary GLB or JSON + external files
Shader model	USD Preview Surface (subset)	PBR metallic-roughness + extensions
Animation	Skeletal & vertex blendshapes	Skeletal & morph targets
Compression	None (but textures may be compressed)	Mesh & texture compression via extensions (e.g., Draco, BasisU)
Primary ecosystem	Apple ARKit/visionOS, Pixar pipelines	WebGL, Khronos 3D Commerce
License	Apache 2.0 reference	Royalty-free Khronos specification

Adoption

USDZ has been adopted by numerous companies and organizations:

• Adobe
• Autodesk
• IKEA
• LEGO
• The New York Times
• Target
• Wayfair
• Home Depot
• Shopify (for AR shopping experiences)

Limitations

Despite its advantages, USDZ has several limitations:

• Platform Specificity: While technically an open format based on open-source USD, USDZ is primarily optimized for Apple's ecosystem
• Limited Interactivity: Animations must be pre-baked; real-time interactivity is restricted compared to native applications
• File Format Restrictions: Cannot include formats like Alembic files that require specific access patterns
• Read-Only Nature: Files must be unpacked and repackaged for editing, unlike editable USD files
• No Native Android Support: Requires third-party solutions for non-Apple platforms
• File Size: Uncompressed nature can result in larger files compared to formats like GLB
• Shader Limitations: Supports only a subset of USD's shading capabilities

Licensing

Pixar's open-source USD — including the **usdzip** utility used to author USDZ archives — is released under the Apache License 2.0, allowing commercial and academic use without royalties. While the USDZ specification is public, Apple retains trademarks for "USDZ" and enforces ARKit viewer compliance. The format itself is an open standard that can be implemented by any developer.

Future Development

The USDZ format continues to evolve with updates to Apple's operating systems and the broader USD ecosystem. Recent and upcoming developments include:

• Support for the HTML `<model>` element in Safari on visionOS
• Enhanced WebAR capabilities
• Improved compression techniques while maintaining direct access capabilities
• Integration with Apple Vision Pro and spatial computing applications
• Continued standardization efforts through the Alliance for OpenUSD
• Potential support for advanced USD features like procedural shading and volume rendering

See Also

• USD (Universal Scene Description)
• ARKit
• RealityKit
• AR Quick Look
• GL Transmission Format (glTF)
• GLB
• FBX
• OBJ
• COLLADA
• WebAR
• 3D file formats
• Augmented reality
• Apple Vision Pro

External Links

• Official OpenUSD website
• Apple AR Quick Look Gallery
• Pixar OpenUSD GitHub Repository
• Blender USD Documentation