USD

In brief: USD (Universal Scene Description) is a scene description format developed by Pixar. USD can map all elements of a 3D workflow pipeline. This includes, for example, the areas of modeling, shading, animation, lighting, FX and rendering. If you like, USD is a much more powerful Alembic.

USD is therefore ideal for exchanging data with other applications (e.g., Omniverse).

USD and Cinema 4D

The first steps towards supporting USD have now been taken for Cinema 4D: primarily the import and export of geometry and materials is supported.

2025

Which animations can the USD import/export handle?

In addition to position, angle and size animations in general, the following settings can be exported and imported as animations for light sources and cameras in particular:

Light: intensity, exposure (EV), color and temperature.
Camera: Focal length, offset, exposure (EV), focus distance, aperture (f/#).

Cinema 4D can open and write the following USD file types:

*.usda: USD file in ASCII format.
*.usdc or *.usd: USD file in binary format.
*.usdz: zipped USD file.

The USD Bridge

Update USD Changes

Close USD Bridge

When Cinema 4D opens a USD file, the program maintains a so-called USD bridge to this file by default. With Update USD changes, changes can be written to this file without completely overwriting the entire file. Several users/programs can access this file at the same time.

You can recognize a loaded USD file with an open USD bridge by the fact that each object has a user tag with a USD icon:

This allows you to distinguish USD objects from normal Cinema 4D objects. The hierarchy of USD objects cannot be changed, but normal objects can be inserted as sub-objects of USD objects and tags can be assigned.

Only one USD bridge to a USD file can exist per scene at any one time. If you add another USD file to existing USD objects, the objects are imported from this file without a USD bridge.

The USD bridge can also be closed using the Close USD Bridge command; there is then no longer a connection to the USD file - which means that it can no longer be changed from the current session. To display this, the USD tags are removed. The objects behave as normal and the hierarchy can also be edited (this corresponds to a normal import, such as from FBX).

Note:If you save a loaded USD scene as a Cinema 4D scene file, close it and open it again, the USD bridge will also be lost. You will need to reload the USD file to re-establish the USD bridge, but any tags and other changes that USD cannot understand (or export from Cinema 4D) will be lost.
Only what Cinema 4D can currently write to a USD file - which is essentially what you find in the options in the USD Express dialog - can be saved in the USD file using the Update USD Changes command.