Houdini 22.0 Nodes Copernicus nodes

Pyro Activate Copernicus node

Changes the activation of VDBs in a Pyro simulation.

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Since 21.0

Note

Although COP Pyro is in COPs, you need DOP level permissions to use it. This means that COP Pyro is not available in Houdini Core, but only in Houdini FX, Houdini Apprentice, Houdini Indie, and Houdini Education.

This node updates the activation of voxels in the VDBs of a Pyro simulation. The solve only occurs where voxels are active, so it’s important to keep the volume being solved active, while also maintaining enough of a buffer so the surrounding air field is present.

You can use the VDB Visualize Tree COP to inspect which regions are activated. Activation is done at the “leaf” level, which are blocks of 8×8×8 voxels. The fewer active leaves, the less memory used and the faster the simulation runs.

Parameters

References

The fields that contribute to the voxel activation.

Density Cutoff

Any leaf whose maximum combined value from the reference fields is below the cutoff will be eligible to be deactivated.

Leaf Dilation

Expand the active region a fixed number of leaves. The maximum of Leaf Dilation Dist and Leaf Dilation is used.

Leaf Dilation Dist

Expand the active region a fixed distance in world space; this is rounded up to the nearest leaf.

The maximum of Leaf Dilation Dist and Leaf Dilation is used.

Velocity Dilation

Each leaf’s maximum velocity in each direction is measured, and the leaf is expanded to cover that distance.

This can ensure the air field is present for incoming air.

Velocity Scale

Tangential Scale

Ambient Velocity

Clip Min X

Deactivate any leaves with world positions less than this in X.

Clip Min Y

Deactivate any leaves with world positions less than this in Y.

Clip Min Z

Deactivate any leaves with world positions less than this in Z.

Clip Max X

Deactivate any leaves with world positions greater than this in X.

Clip Max Y

Deactivate any leaves with world positions greater than this in Y.

Clip Max Z

Deactivate any leaves with world positions greater than this in Z.

Inputs

density

A float VDB used both as the reference size for activation and to provide values to cull inactive leaves.

temperature

A float VDB used both as the reference size for activation, and to provide values to cull inactive leaves.

v

A vector VDB providing the velocities for doing velocity dilation.

flame

A float VDB used both as the reference size for activation, and to provide values to cull inactive leaves.

activate_pts

Additional points to activate with. Any leaf which contains the point will be activated.

Outputs

vdb_ref

A VDB reference with leaves activated by the rules.

See also

Copernicus nodes