USD Layer Editor

USD Layer

A single layer is composed of an ordered list of sublayers, which form the content of the top level layer (the root layer). In Maya, the two types of layers you can have are the following:

File-backed/ Existing Layer: A layer that has been saved to a file on disk.
Anonymous Layer: A layer that has not been saved to disk. When newly created, this is an empty layer. Once edits are made, you will be prompted to save this layer.

Opinions

Layers contain opinions about the prims in the scene. Creating a value for an attribute, metadata or relationship also creates an opinion for the object on the layer. The strength of the layers in the layer stack determines which opinion is expressed in the scene. One object may be affected by multiple opinions for different layers. In USD, LIVRPS strength ordering provides a framework the ordering of opinions. For example, if the asset department creates a green teacup with the diffuse color of (1,0,0), the teacup is assigned this diffuse opinion. At a later date, the lighting department decides to make the teacup white with a diffuse color of (2,0,0). According to LIVRPS rules, the strongest opinion wins. With the local layer in the layer stack being strongest, the teacup is rendered white.

Windows > USD Layer Editor
In the Outliner, right-click a prim, stageShape, or stage and select USD Layer Editor

In Maya, you can organize and edit USD scene description in layers using the USD Layer Editor. Layers enable non-destructive editing, allowing different departments in the same pipeline to collaborate and update assets without interfering with each other's work. For example, if you start with an existing scene and create a new layer containing your edits, these edits won't affect anyone else using the same scene unless they decide to include your new layer.

Important: As a form of best practice, avoid performing edits (either via Manipulators, the Attribute Editor or the Outliner) to weaker layers in your layer stack. Edits performed to weaker layers will be blocked as the USD framework is based on top level layers having stonger opinions that override those of weaker layers in the stack.

USD Layer Editor Interface

#	Element	Description
1	Create New Stage	Select from this menu to create a new USD stage or use an existing USD file to create a stage. If you select Create USD Stage from File, a browser will appear to let you select an existing file. See Create a USD stage.
2	Stage File	A stage is a USD root file and all of its layers. In Maya, the equivalent to a stage is a scene. For example, we load a scene in Maya, but we compose a stage in USD. Select Create and choose Stage with New Layer or Stage from File. Tip: You can pin or unpin stages to change the focus of the USD layer editor while you work with multiple stages.
3	Add a new layer	Click to add a new anonymous sibling layer to the selected layer or the root layer (if no layer is selected).
4	Load a sublayer	Click to load an existing layer as a sublayer to the selected layer or the root layer (if no layer is selected). Loading a sublayer brings up the Load Sublayers to `<LayerName>` dialog. See Load sublayers to USD Layer Editor. Tip: You can save USD sublayers as relative to parent layers. To enable saving USD files relatively, see Make Path Relative.
5	Save Stage	Click to save a stage and bulk save any unsaved edits on your stage. The number of unsaved edits is displayed beside the save stage icon. See Save edits in the USD Layer Editor. Tip: You can save USD files relatively to your Maya scene file and parent file directories. To learn more about saving USD files relatively, see Make Path Relative.
6	Pin Stage	Click to pin a stage. When pinned, the stage selection in the drop-down beside is respected, without shifting focus. When unpinned, updates the drop-down and the Layer Editor to follow the selected stage or prim in the stage from the Outliner. Tip: Setting a pin will trigger a scene save. Also, your pin state and stage will be remembered between Maya sessions.
7	Target Layer	When a layer set as the target layer, appears next to the layer name, and any scene edit operations are made on this layer.
8	Muted Layer	Click to mute a layer. When a layer is muted, it is ignored by the stage and the contents of the muted layer disappear in the Viewport and Outliner. Muted layers do not participate in value resolution or composition and do not appear in any Layer Stack. Muting is advantageous if a particular layer is affecting performance or having an undesirable effect on the scene.
9	Dirty Layer	When unsaved edits are made to any layer, the layer becomes "dirty" with changes that need to be applied and confirmed in the layer stack. An asterisk appears next to the layer with unsaved changes. See Save edits in the USD Layer Editor.
10	USD Layer Editor contextual menu	Right-click a layer to select options from the contextual menu. See USD Layer Editor contextual menu.

Important: Read-only layers or layers with metadata SetPermissiontoEdit=False will have limited capabilites from the full set of options in the Layer Editor. See read-only layers in the USD Layer Editor contextual menu to learn more.

Related Concepts: The USD Layer Editor is unique to Maya, but it's based on concepts that are explained in the Pixar USD glossary. If you're new to USD, you can get started by learning about relevant terms including, layer, layer stack, root layer stack, session layer, stage, composition, composition arcs, LIVRPS strength ordering, opinions, and references.