USD Fundamentals

OpenUSD (Open Universal Scene Description) is a framework and file format used to describe complex 3D scenes. It allows applications to represent objects, geometry, materials, lighting, and relationships within a structured scene graph. OpenUSD is widely used in animation, visual effects, simulation, and increasingly in real-time 3D applications.

OpenUSD supports multiple file formats for different purposes. The most common are the human-readable .usda format and the compact binary .usdc format. The text format is useful for learning and debugging, while the binary format is optimized for performance and large scenes.

OpenUSD organizes data using a scene graph, where objects are arranged in a hierarchical structure. Each node represents an element in the scene such as a transform, geometry, camera, or light.

OpenUSD provides several primitive types for representing geometry, including meshes, curves, and points. These primitives describe the shape of objects in the scene.

Objects in a USD scene can be positioned using transformations such as translation, rotation, and scaling. These transformations allow objects to be placed correctly within the scene.

OpenUSD allows objects to reference materials that define their visual appearance. Materials describe properties such as color, surface reflection, and texture.

OpenUSD supports referencing external assets. This allows large scenes to reuse models, materials, and components without duplicating data.

One of the most powerful features of OpenUSD is its composition system. Scenes can be built from multiple layers that combine to form the final result. This allows different artists or tools to work on separate parts of the scene.

OpenUSD is used to coordinate complex 3D production pipelines involving modeling, animation, lighting, and rendering. It allows multiple tools to work on the same scene description without breaking compatibility.