Houdini 17.0 Nodes VOP nodes

Anti-Aliased Flow Noise VOP node

Generates anti-aliased (fractional brownian motion) noise by using the derivative information of the incoming position to compute band-limited noise.

This operator generates anti-aliased (fractional brownian motion) noise by using the derivative information of the incoming position to compute band-limited noise. This type of noise is ideal for shading.

This operator is very similar to the Anti-Aliased Noise but adds some extra options to deal with flownoise.

Flow is your position in flowspace. This can be thought of as an extra dimension to your noise, but has a fixed period of 1. Unlike normal approaches to adding another dimension, it operates by rotating the noise vectors, thereby resulting in a flow-like behavior rather than dimension slicing-like behavior.

Flow rate is analogous to roughness, but applied to the flow dimension. Values greater than 1 appear like turbulence where higher frequencies spin faster than lower frequencies. Values less than one make the finer detail appear to float on the surface of the low-frequency flow.

The advection term enables backward-tracing of the noise on each successive frequency. This helps the higher frequency noise to stick with the low-frequency flow, but is much more expensive.

The roughness parameter determines the coarseness of the noise. The maxoctaves parameter limits the noise to a fixed number of iterations.

The noise generated is centered at 0 and typically has values between -0.5 and +0.5.

Make sure at least the Position (pos) input is connected in order to notice any noise. The easiest way to accomplish this is to pipe the global variable P into the pos input. However, the global variable is in camera space, so noise will move through the surface.

To fix this use the Rest Position VOP (for deforming geometry) or simply transform the position to object space using the Transform VOP.

Connect the noise output to the Color Mix bias or to Displace Along Normal to obtain interesting results. The options are boundless.

Examples

The following examples include this node.

attribfromvolume Example for Attribute from Volume geometry node

This example demonstrates how the AttribFromVolume SOP can be used to transfer volume values onto point attributes.

volumecompress Example for Volume Compress geometry node

This example shows how to use the Volume Compress SOP to reduce the memory requirements of volumes without too adversely affecting their appearance.

volumesurface_hierarchy Example for Volume Surface geometry node

This example shows how to use the Volume Surface SOP to surface a hierarchy of SDFs using explicit grading.

See also

VOP nodes