Models, Materials and USD

USD

The fundamental representation for assets in Omniverse is Pixar’s open-source Universal Scene Description (USD). While USD includes a file format, it is much more than that. USD is a powerful scene representation with an API that allows complex property inheritance, instancing, layering, lazy loading and a wide variety of other key features. Omniverse uses USD for interchange through the Nucleus DB service.

Additional and Recommended Source of USD Information

What Makes USD Unique

5 Things To Know About USD

Converting to USD

The Omniverse gives you all the tools you need to quickly and easily convert assets into and out of USD.

Asset Converter

Accessible via Apps on the omniverse, users can convert models into USD using the Asset Converter Service (Extension).

Format	Name	Description
.fbx	Autodesk FBX Interchange File	Common 3D model saved in the Autodesk Filmbox format
.obj	Object File Format	Common 3D Model format
.gltf	GL Transmission Format File	Common 3D Scene Description

Connectors

Specialized connectors offer a more finely tuned conversion process. Through connectors, native files are directly translated to usd.

Note

Because connected applications often have numerous file conversion capabilities, a path to even the most obscure formats may be possible via various connectors.

MDL

NVIDIA has developed a custom schema in USD to represent material assignments and specify material parameters. In Omniverse, these specialized USD’s get an extension change to .MDL signifying that it is represented in NVIDIA’s open-source MDL (Material Definition Language).

MDL Texture Formats Accepted

Extension	Format	Description
.bmp	Bitmap Image File	Common image format developed by Microsoft.
.dds	DirectDraw Surface	Microsoft DirectX format for textures and environments.
.exr	OpenEXR	High Dynamic Range format developed by Industrial Light and Magic
.gif	Graphical Interchange Format File	Common color constrained lossless web format developed by CompuServe.
.hdr	High Dynamic Range Image File	High Dynamic Range format developed by Industrial Light and Magic.
.jpeg	Joint Photographic Experts Group	Common “lossy” compressed graphic format.
.jpg	Joint Photographic Experts Group	Common “lossy” compressed graphic format.
.tif	Target Image File Format	Common “lossless” and “lossy” graphic format.
.png	Portable Network Graphics File	Common “lossless” compressed graphics format.
.psd	Adobe Photoshop Document	The native format for Adobe Photoshop documents.
.tga	Truevision Advanced Raster Graphics Adapter	High Quality raster graphic format developed by Avid Technology |

Extending USD

Universal Scene Description is also extensible to support new data models and workflows. This is primarily done using USD schemas. NVIDIA has developed custom USD schemas to represent general physical properties of objects (e.g. mass, moment of inertia), the way they are constrained to move (e.g. pivots, joints) and parameters specific to a particular Physics simulator (e.g. NVIDIA’s open-source PhysX).

For more information on custom schemas, please see our USD Schemas documentation