Use a Material Library USD File#

While the car and its initial materials were successfully exported from DELTAGEN as USD Preview Surface, those materials are basic versions only used as placeholders and to bind materials to the geometry. Next, you may want to bring in a separate, high quality material library as a layer and incorporate it into the project.

This layer can be worked on independently by other developers so work efforts can be parallelized. If at any point this layer is updated, the upstream files such as our main concept car file can be updated.

This layer, and subsequent layers, were added to the project level file (ConceptCar.usdc) using the steps listed below. Note: This file in the Authored folder already has these changes made to it for you for reference.

  1. Open the project USD file in the Authored folder (ConceptCar.usdc). This is the top level file you may edit by adding layers rather than modifying the prims in the file directly. These changes are non-destructive and can be disabled at any time using the Layers panel.

  2. Next, navigate to the Layer panel. The first optimization script converts the Variants file from a reference to a layer. It is visible here.

  3. Next, add Material_Library.usd from the Authored/SubUSDs folder by selecting the Insert Sublayer icon at the bottom of the Layer panel.

This USD contains all of the high quality materials used in the final stage. These materials should be saved together as a single USD file, and referred to as a library, so the same library may be used by many projects. This way, any changes to this central material library are reflected in any USD composition that includes this library.

  1. Optional: Lock the Material_Library.usd layer using the lock icon on the right of the Layer panel to avoid making unintended changes to the layer. In the Stage panel, notice there is now a Looks folder with all of the new materials. This step adds the Material Library as a layer, but does not assign any of the materials to the geometry in the stage. This is completed on a separate layer in a future step.