File extension

.usd

Universal Scene Description (USD)

.usd files are Universal Scene Description scenes: a framework and file format from Pixar for describing, composing, and exchanging large 3D scenes, with .usda (text) and .usdc (binary crate) as related forms.

Known meanings

Formats and reference material for .usd

Universal Scene Description (USD)

Pixar 3D scene description format; .usd may hold either text or binary data, .usda is text and .usdc is binary

  • 3d-graphics
  • Pixar Animation Studios / Alliance for OpenUSD
Open link

Details

Format notes

Universal Scene Description (USD)

Universal Scene Description, or OpenUSD, is a system developed by Pixar Animation Studios for building and interchanging 3D scenes. It was released as open source in 2016 and is now stewarded by the Alliance for OpenUSD (AOUSD). Rather than being only a model format, USD provides a scene graph and a composition engine that lets many artists layer, reference, and override parts of a scene non-destructively.

Technical Notes

USD files come in several encodings. .usda is human-readable text, .usdc is a compact binary “crate” format, and .usd is a generic extension that may contain either, so tools detect the actual encoding when opening it. A binary crate file starts with the identifier PXR-USDC. Scenes consist of layers containing prims (objects) with typed attributes and relationships, and composition arcs such as sublayers, references, payloads, variants, and inherits combine layers into a final stage. Schemas define types such as meshes, materials, lights, and cameras. A related .usdz package bundles a scene with its textures for distribution.

Adoption

USD is used in film and visual effects pipelines and is supported by tools including Houdini, Maya, Blender, NVIDIA Omniverse, and Apple platforms. The open source runtime is available with C++ and Python APIs.

Preservation And Security Notes

The .usda text form is the best choice for inspection and long-term storage, while .usdc suits performance. Scenes frequently reference external files by path, so archive those assets together or package them as .usdz. Treat files from unknown sources carefully, as USD scenes can reference external paths.

Further Reading

  • OpenUSD documentation: https://openusd.org/release/index.html
  • Alliance for OpenUSD: https://aousd.org/