Turn this on and specify a group name (or a space-separated list of group syntax) to import. If you turn this on but leave the field blank, it imports all geometry.

Specifies whether the Import Group is a point or primitive group.

If a prim being imported has an automatically generated name (like mesh_0) because it had no path primitive, or if it has a path primitive but the path is relative (does not start with /), the node automatically prefixes the name/path fragment with this path. This is a way of keeping “un-pathed” prims organized under a single branch. (See how to create geometry hierarchy.)

(The default is /$OS which puts “un-pathed” prims under a root prim with the name of this node.)

Specifies whether the geometry should be transformed into world space before being written out. This applies the object-level transform to the Relative Path Prefix prim and any other root prims in the generated USD stage.

Click to write out the layers generated by a LOP network to USD files.

Starts another copy of Houdini in the background and instructs that copy to cook and save the USD files generated by the LOP network. This allows one to continue working in the current Houdini session.

Click to open a dialog that lets you launch a “one-off” render with different frame range and dependency settings.

See saving animation above for more information.

When Valid Frame Range is Render Frame Range or Render Frame Range (strict), the start and end frames (inclusive) and interval.

Render with the parameter values stored in this take.

The “top-level” USD file to write the root layer to. Other layers that have file path metadata set will be written to their own USD files. A default output processor (see below) translates external file references in nodes to be relative to this file’s directory, as is recommended.

When this is on, the node writes out each frame’s data to disk before cooking the LOP Network to generate the next frame of data. When this is off (the default), the node cooks the data for all frames into memory and writes out the animated files all at once. Turning on this option ensures that only a single frame worth of data is in RAM at any one time, allowing arbitrarily large USD files to be created. But saving each frame can be slightly slower, and the generated files may be larger because of the way USD files append new data to an existing file. See saving animation above.

When this option is on, this ROP can also generate separate USD files for each frame. To do this, embed the local variable for the current frame number in the Output File path (and other layer save paths) so each frame will write out files with unique names. For example:

$HIP/usd/scene_$F4.usd

See expression in filenames for more information.

LOP networks may generate vastly different scene graphs from one frame to the next. When combining these scene graphs over a frame range into a single animated scene graph, the set of primitives in the combined scene graph will be the union of the primitives in each frame’s hierarchy. But if a mesh appears at frame 50, this generally means that it is desired for this mesh to not be visible prior to frame 50. Enable this option to cause this node to track a list of all primitives at each frame, and automatically author animated visibility attributes for any primitives that are added to or removed from the scene graph over time. This gives the appearance of primitives being added and removed over time.

Only subclasses of UsdGeomImageable primitives will be tracked this way, since these are the only USD primitive types which respect the visibility attribute.

When running on Windows, the USD library often has issues saving layers to network mounted drives when those layers are currently loaded into a USD stage. This can make it impossible to overwrite a USD layer that is in use, even by the current Houdini session. This option works around this issue by having the USD ROP mute each layer right before ti is saved to disk (but only when running under Windows - on Linux and MacOS this parameter has no effect). Once the layer is saved, it is un-muted. This approach incurs a performance penalty as any stages using this layer will be recomposed twice instead of once. But in some settings this can make the save process much more robust.

This processor changes absolute file paths to relative paths in layer files. This allows you to use paths such as $HIP/usd/foo.usd for loading, but have them written out as paths relative to the source file. This is recommended practice so you probably do not want to remove this processor.

Initialize DOP simulations before rendering.

Print percentage complete value as files are written. This is in the style expected by Pixar’s Alfred render queue.

Print the number of bytes sent or received by the distributed simulation nodes during cooks triggered by this node.

This does not track network usage from, for example, saving a file to an NFS mount. It only tracks the network communication of distributed Houdini nodes.