Houdini 20.0 Nodes Geometry nodes

Cloud 2.0 geometry node

Creates a volume representation of source geometry.

This node type is deprecated. It is scheduled to be deleted in an upcoming revision of Houdini.

Use VDB from Polygons and Cloud Noise tools

(Since version 20.0.)

Since 18.0

Deprecated

The Cloud SOP is now deprecated. Use VDB from Polygons or VDB from Particles, then use the Cloud Noise tools (Cloud Noise, Cloud Billowy Noise SOP, or Cloud Wispy Noise SOP).

This node takes an existing polygon or point cloud source geometry and create a volume representation. Optionally it can create additional secondary details to create more cloud like appearance.

Note

The workflow is intended to generate clouds without needing to simulate for fast results. Animation to the cloud shape can be achieved by using various Offset parameters, like the Noise Offset parameter.

If a simulation, is required the Sparse Billowy Smoke tool on __PyroFX] shelf is a good place to start (with slow time scale and things like buoyancy).

Parameters

Volume

The first stage in creating a cloud is to create a VDB that represents the cloud volume. These parameters control how that is performed.

Source

Controls how the incoming geometry is interpreted.

Polygon Model

The source should be a closed, watertight, polygonal mesh.

Point Cloud Model

The source is a cloud of points.

Note

This does not work with the shape scattering.

Point Radius Scale

When stamping a point cloud model, the pscale attribute will be scaled by this amount.

Uniform Sampling

It is useful to make sure voxels in a volume are cubes. This option allows the resolution of the volume to be specified without having to worry about matching the size and resolution fields. The maximum axis will be used for the division.

Uniform Sampling Divs

The number of voxels to divide the maximum axis into. The other axes will be divided into the number of cells that fit for this voxel size.

Div Size

The uniform size of the voxels, when specifying the voxel size directly. The given sized box will be filled by voxels of this size.

Use World Space for Band

Determines the width of the converted VDB in terms of worldspace rather than voxels.

Half-Band Voxels

How many voxels outside the point sphere to fill in the generated VDB (when Use world space for band is off).

Half-Band

How many Houdini units outside the point sphere to fill in the generated VDB (when Use world space for band is on).

Max Half-Width

The maximum allowed half-width in voxel units. Avoids inadvertent excessive computation of extraordinarily wide bands when world space band computation is used.

Exterior Band Voxels

How many voxels outside the surface to fill in the generated VDB (when Use world space for band is off).

Exterior Band

How many Houdini units outside the surface to fill in the generated VDB (when Use world space for band is on).

Interior Band Voxels

How many voxels inside the surface to fill in the generated VDB (when Use world space for band is off).

Interior Band

The distance to compute the distance field inside the mesh.

Density

These options control the conversion of the SDF version of the object into a fog version of the object.

Density Multiplier

Overall multiplier for final density.

Density Ramp

Ramp lookup for density field. This controls how the density falls off across the boundary of the object. The length of the boundary fall off is controlled by the interior bandwidth specified in the Volume page.

Scatter Shapes

The provided geometry can optionally be filled with a cloud of spheres. These then create a puffy cloud like version of the object.

Spatial Scale

This sets the spatial scale used by the scene. It will be modified by the Unit Length specified in the Houdini preferences on node creation. For default Houdini units of 1m, this will be set to 1. If working in centimeters, this will be set to 100. It can be further modified if needed.

Visualize As Polygons

Display the resulting geometry as polygons.

Smoothing

Smooths the generated surface prior to converting to fog. This rounds out sharp internal corners that tend to form where spheres intersect.

Voxel Radius

The number of voxels to run the smooth operation over. This is measured in voxels, not distance. This distance defines a cube, so increasing the radius will exponentially increase the work.

Fill Source

Fill the source input with spherical shapes.

Random Seed

Random seed used in jittering positions.

Shape Size

Overall size of the spherical shapes. This is measured in world space. If it is too small compared to the voxel size specified on the Volume tab, the points won’t be added to the final object. If it is too large, no points may be selected inside of the object.

Scatter Multiplier

Overall multiplier on the amount of shapes generated when filling source.

Noise Min

Minimum scale of generated shapes.

Noise Max

Maximum scale of generated shapes.

Noise Frequency

Frequency of the noise used in random scaling.

Noise Offset

Noise offset used in random scaling.

Secondary Shapes

Create additional shapes on top of the source geometry.

Use Painted Attrib

You can paint a custom attribute which will determine where additional geometry is created.

Scatter Attrib

Name of the custom attribute.

Iterations

Number of loops used to build up secondary shapes.

Random Seed

Random seed used when generating secondary geometry.

Shape Size

Overall size of the secondary shapes generated.

Scale Multiplier

Multiplier of scales of secondary shapes.

Noise Min

Minimum scale of secondary shapes.

Noise Max

Maximum scale of secondary shapes.

Noise Frequency

Frequency of the noise used in random scaling.

Noise Offset

Noise offset used in random scaling.

Up Vector Falloff

Scaling of secondary shapes relative to an up vector.

Up Vector

User specified Up Vector.

Angle

Angle relative to the up vector that will be used when scaling secondary shapes.

Bias

How quickly the scale is affected by the Angle relative to the Up Vector.

Billow Offset

Transforms the secondary shapes away or towards each other.

Tip

Animating the Billow Offset can provide a slow changing movement effect

Density Offset

Transforms the secondary shapes based on their proximity to each other.

X Axis Shape Profile

Adjusting this curve will allow for shaping of the x axis profile of the generated secondary shapes.

Y Axis Shape Profile

Adjusting this curve will allow for shaping of the y axis profile of the generated secondary shapes.

Z Axis Shape Profile

Adjusting this curve will allow for shaping of the z axis profile of the generated secondary shapes.

Flatten

The flatten operation applies a non-linear stretch to the cloud. This can be very useful for flattening out the bottom of thunder clouds.

Flatten

Enables flatting controls which can be used to flatten parts of the cloud object.

Flatten Origin

Center origin where the flatten effect will be based on.

Flatten Up Vector

Direction in which the flatten effect will occur.

Top Scale

Controls the amount of flatten/stretch effect above the origin along the up vector.

Bottom Scale

Controls the amount of flatten/stretch effect below the origin along the up vector.

See also

Geometry nodes