The Alembic ROP can export your scene as an Alembic archive. See the following link for further information about the Alembic format.
Controls whether this render node outputs the current frame (Render any frame) or the image sequence specified in the Start/End/Inc parameters (Render Frame Range).
Render Frame Range (strict) will render frames START to END when it is rendered, but will not allow frames outside this range to be rendered at all. Render Frame Range will allow outside frames to be rendered. This is used in conjunction with render dependencies. It also affects the behavior of the 'Override Frame Range' in the Render Control dialog.
The name of the archive to generate.
The file format of the archive to generate.
Use whichever file format is the default for the current version of Houdini.
Use the HDF5 file format. HDF5 is a common hierarchical data format, and several tools exist to view and edit HDF5 files.
Use the Ogawa file format. Ogawa is an Alembic-specific file format available for use as of Alembic 1.5. Ogawa files are on average smaller (by 5-15%) and faster (4× for single-threaded reads, 25× for multi-threaded reads on 8 core systems) than HDF5 files.
Create the directories in the Alembic archive output path if they do not exist.
Normally, it’s best to render all frames into a single Alembic archive. This allows Alembic to optimize storage of data and to be more efficient. This is the default behavior of the output driver, even when frame-by-frame rendering is requested.
In some work-flows, you may want to have the Alembic ROP operate on a frame-by-frame basis (see the -I option on the hscript render command). Turning this toggle off will let the ROP evaluate frame-by-frame.
Reset simulations before writing Alembic archive.
Instead of exporting objects contained under a root object, the Alembic ROP can export a single geometry detail specified by a SOP path. The SOP path export method is enabled by this parameter.
The path to the geometry detail to include in the alembic archive.
If a group name is specified here, any polygons in any objects will be saved as subdivision primitives in the Alembic file. Other polygons will be saved as polygon mesh nodes.
The subdivision group can be specified per object with the object level parameters vm_rendersubd or ri_rendersubd. If present, they will be used to control whether polygons will be saved as subdivision primitives and the vm_subdgroup parameter will be used to select which polygons will be rendered as subdivision surfaces.
Use a primitive string attribute to directly specify the path of a primitive in the output archive.
The name of the attribute containing the path.
The root object of the scene. All displayed objects contained under this node will be included in the Alembic archive.
A pattern/bundle of objects to include in the alembic archive.
This option can be used to skip writing transform nodes which have no transform (an identity transform) for the entire animation.
When importing an Alembic scene, there are often empty geometry nodes created to contain Alembic SOPs. These objects are simply placeholders to contain the geometry. However, when exporting the scene, they will be added as dummy transform nodes (roughly doubling the size of the Alembic archive node count).
All geometry containers (geometry objects containing SOPs) will be saved as Alembic transform nodes.
All geometry containers which are not animated and have an identity transform will be skipped when writing the Alembic file.
All geometry containers will not be written to the Alembic file. In some cases for subnet hierarchies, having a subnet parent animated will propagate the time dependence to the contained nodes. This option allows you to forcibly skip the geometry nodes.
Any transformations on these nodes will be lost during the save.
If an object has a parameter named abc_collapse that evaluates to a non-zero value, the object will be skipped from the save. This allows fine-grained per-object control regardless of the setting of this parameter.
If this checkbox is turned on, hidden objects matching the Objects pattern/bundle will also written to the Alembic archive.
If this checkbox is turned on, the geometry in the Display SOP will be saved instead of the geometry from the Render SOP.
When saving a complex piece of geometry, it is possible to partition the geometry into multiple shape nodes by splitting up the primitives based on a string attribute. There are several different ways to interpret the string values.
The geometry will be output as a single Alembic shape node.
The value of the string attribute is used to name the shape node. This mode is ideal when using the name attribute.
When loading an Alembic file, you can store the Alembic path in a string attribute. This option will partition the geometry based on the names of the shape nodes stored in the attribute.
This option will partition the geometry based on the names of the transform nodes stored in the attribute.
Combines both the transform and shape node names to form the name for the new shape node.
Specifies a string attribute which is used to partition a single geometry into multiple Alembic shape nodes. For example, you can use the name or the abcPath attribute to split a single piece of Houdini geometry into different Alembic shape nodes based on the string value.
This will cause all Alembic nodes to have proper bounding boxes written. Computing bounds for only the shape nodes is more efficient.
When saving a complex piece of geometry, it is possible to partition the geometry into multiple shape nodes using packed primitives. There are several different ways to handle packed primitives.
The packed primitive’s transform will be baked in to the resulting shape node’s geometry.
A transform node will be created above the packed geometry.
The packed primitive’s transform will be baked in to the parent transform node.
This will cause packed objects to be instanced within the Alembic archive during write, reusing geometry and potentially decreasing the size of the file.
This will cause Alembic shape nodes to be created for geometry.
If this checkbox is turned on, geometry attributes will be saved to the Alembic file as arbitrary geometry parameters.
Point attributes whose name matches this pattern will be saved in the Alembic file.
Vertex attributes whose name matches this pattern will be saved in the Alembic file.
Primitive attributes whose name matches this pattern will be saved in the Alembic file.
Detail attributes whose name matches this pattern will be saved in the Alembic file.
Promote primitive attributes matching this pattern to detail attributes before exporting to Alembic. Sometimes when importing Alembic, Houdini must convert constant Alembic data to uniform data. This option lets you manually re-adjust certain attributes on export.
The normal behavior when promoting primitive attributes to detail attributes is to validate that the values are the same for all primitives. Enabling this option will bypass this check forcing all matching primitive attributes to be converted to detail attributes regardless. The attribute value of the first primitive will be used as the single detail value for the exported primitive.
Detail attributes whose name matches this pattern will be saved as arrays instead of scalars.
Additional UV attributes whose name matches this pattern will be saved in the Alembic file.
This parameter controls how Houdini primitive groups will be translated to Alembic face sets. Alembic only supports face sets for polygon and subdivision meshes.
No face sets will be saved out.
Only groups which contain polygons will generate face sets in the Alembic file.
Face sets will be created for all groups, regardless of whether the group contains any polygons.
When enabled, the resulting Alembic archive will only export the subset of the scene specified by parameters on the Layering tab.
When enabled, all data for ancestors to non-pruned nodes specified by the Nodes multiparm will be exported.
Use this multiparm to specify which nodes the resulting Alembic layer will fully prune, replace, or merge. Click the + button to add a new rule.
Use this multiparm to specify which nodes the resulting Alembic layer will have their visibility changed. Click the + button to add a new rule.
Use this multiparm to specify which attributes the resulting Alembic layer will prune or replace. Click the + button to add a new rule.
Use this multiparm to specify which face sets the resulting Alembic layer will prune or replace. Click the + button to add a new rule.
Use this multiparm to specify which user properties the resulting Alembic layer will prune or replace. Click the + button to add a new rule.
Enabling this will cause sub-frame geometry to be saved to the Alembic file.
The number of sub-frame motion samples to be saved.
The open/close of the shutter for sub-frame motion samples.
This example demonstrates how to produce an alembic (abc) file from a sop node using the top rop alembic node.