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You can use this node in combination with the Auto Select LOD node to automatically select one of the generated LOD variants based on the primitive’s distance from the camera.
Set up the geometry object in the USD scene tree.
For example, you could use a SOP Import to import a model from a SOP network as a USD geometry prim at
Add a Create LOD node.
In the Create LOD node’s parameters, set the Primitive path to the path of the prim you want to create LOD versions of (for example,
Set the Variant set name to something meaningful, like
Set the Number of LODs to the number of variants you want to create (including the original).
Set the first Keep percent value to
100(this is to show the original model close-up). Then set each subsequent Keep percent value to lower percentages.
For example, if you have 4 levels, you might set the keep percentages to
100, 75, 50, 25.
Later in the network, you can add an Auto Select LOD node to automatically select a level of detail based on distance to the camera.
See the help for the Auto Select LOD node for more information.
The path to the primitive to which the new variant information will be added.
The path to the primitive that is the base definition on which the variants will be authored. This primitive will be referenced into the new primitive at the primitive path where the variant will be defined. This indirection ensures that opinions in the variant will be stronger than opinions that already exist on the source primitive.
Warn of weak variant opinions
Adds a warning if any variant opinions are weaker than existing opinions. As each variant is added, this option examines the composed stage with that variant selected. If any opinions added by the variant are not the strongest opinion on the composed stage, add a warning. Turn off this option to avoid the performance penalty of checking for this condition.
If no primitive exists at the specified Primitive Path, and this node must create a new Xform primitive at the specified location, this parameter controls the Kind that will be authored on this new primitive.
Parent primitive type
If no primitive exists at the specified Primitive Path, and this node creates a new primitive at that location, this parameter controls the primitive type of any ancestor primitives that may have to be created prior to creating the final primitive.
The name of the variant set to which this node should add its variants.
Variant source primitive
The path to the root of the primitives that should be copied from each variant input’s scene graph into the variant.
Variant Name Root
The base name to be used for the variants being created. The node creates variant names by appending numbers to this string, starting with ID offset. For example, the default
LOD_ produces variants named
LOD_2, and so on.
The initial number to add to the Variant name root for the first generated variant. For example, if you change this to
2, this node would generate variants named
LOD_4, and so on. This may be useful to combine the results of two different Create LOD nodes as a single variant set.
When this is on, the node sets the variant name in Variant name as the current variant. This is useful for visually checking what the different levels looks like.
When Display variant is on, the node will set the variant with this name as the current variant in the output. For example, if the node is set to produce three variants
LOD_2, you can turn on Display variant and set this to
LOD_1 to view the middle level of detail.
Number of LODs
The number of level of detail variants to create.
What percentage of the original polygons to keep. Setting this to
100 to pass through the original model. Usually you should set the Keep percent for each level to decreasing values starting with
If the input geometry has quads, the PolyReduce node will remember which polygons were quads (even though the internal algorithm works on triangles) and output corresponding quads on the reduced model. An all-quad input should produce an all-quad output.