# Universal Scene Description (USD) Importer

## Import Options

The following options are supported when importing from USD.

### Global Read Flag
> Set read flag for all usd import mesh sequence cache modifiers.

### Manual Transform

>#### Scale
>Value by which to enlarge or shrink the objects with respect to the world's origin.

### Relative Path
> Select the file relative to the blend file.
### Set Frame Range
>If checked, update scene's start and end frame to match those of the USD archive.

### Import Subdiv Scheme
> If enabled, subdiv surface modifiers will be created based on the USD SubdivisionScheme attribute.

### Import Instance Proxies
> If enabled, USD instances will be traversed with instance proxies, creating a unique Blender object for each instance. Note that this option is ignored if the experimental Instancing option is also checked

### Visible Prims Only
> If enabled, invisible USD prims won't be imported. Only applies to prims with a non-animating visibility attribute. Prims with animating visibility are always imported.

### Create Collection
> If enabled, all import objects will be added to a new collection.

### Convert to Z Up
> When checked and if the USD stage up-axis is Y, apply a rotation to the imported objects to convert their orientation to Z up.

### Light Intensity Scale
> Value by which to scale the intensity of imported lights.

### Prim Path Mask
> If set, this will import the specified primitive from the usd stage.

### Primitive Types
> Specify the USD primitive types to import as Blender objects.

* Cameras
* Curves
* Lights
* Materials
* Meshes
* Volumes

### Purpose
> When the Guide, Proxy or Render selections are checked, geometry wih the given purpose will be imported.

### Experimental

> #### Instancing
> When checked, USD scenegraph instances are imported as collection instances in Blender. Note that point instancers are not yet handled by this option. Below is a screenshot of an instance collection prototype being edited in Blender.

> 

>#### USD Preview Surface
> When checked, convert UsdPreviewSurface shaders to Principled BSDF shader networks. The image below is a screenshot of USD preview of a complex scene in Blender.

>

>### Set Material Blend
>When checked and if the Import Usd Preview option is enabled, the material blend method will automatically be set based on the shader's opacity and opacityThreshold inputs, allowing for visualization of transparent objects.

## Animation Support
The importer supports two types of animation:
* **Animating transforms.** If a USD primitive has an animating transform, a transform cache constraint will be applied to the imported Blender object.
* **Cache modifiers.** Animating mesh and curve geometry is supported by applying a cache modifier to the imported data. Primvar animation is currently supported only for mesh display colors and UVs.