Noise Operator

The Noise operator adds procedural noise to strands, and can optionally animate it. It is a flexible way to break up regularity in a groom, and because the noise can move over time, it doubles as a cheap source of motion - faking wind on short hair, or adding a layer of movement on top of already-simulated hair.

What it does

Noise displaces strands using a procedural noise field, which you scale with an amount control. Unlike the Frizz Operator, whose displacement is fixed per strand, the Noise operator can vary over time, so the same controls serve both static shaping and animation.

Animating noise

Enable animation to make the noise field evolve over the timeline. This gives gentle, continuous motion without a full dynamics simulation - useful for ambient movement, distant characters, or adding life to a static groom.

Targeting strands

A strand group parameter confines noise to part of a groom, and the amount can be driven by a strand channel or map so the effect varies across the surface.

Noise that follows the surface

By default the noise is sampled at each strand's position, so when the base mesh moves or deforms the hair slides through the noise field and the pattern appears to swim over the hair. Enable Rest Space to sample the noise at each strand's root texture coordinate and along its length instead: the noise then stays attached to the hair however the surface moves. Strands without texture coordinates get a fixed random position.

In Rest Space the size of the noise follows the texture coordinates (1 UV unit counts as 100 scene units), so Scale usually needs adjusting after turning it on, and the noise is finer where the UVs are denser. World Space has no effect in this mode.

Clumps moving together

Correlation sets how much strands of a group share the same noise, from 0 (each strand on its own) to 100% (the whole group moves as one). Groups come from the Correlation Group channel, or, when none is set, from the ClumpIds channel that the Clump Operator writes, so clumped hair moves clump by clump.

Frizz Operator - static, length-preserving irregularity.
Moov Physics Operator - full dynamic simulation when you need real motion.