Yusuf's Thoughts

Noise - CHOP and TOP

2 min read

Noise Operators

Noise is the foundation of organic movement, procedural textures, and generative behavior in TouchDesigner. You will use the Noise CHOP and Noise TOP in almost every project.

Noise Types (Algorithm)

Both TOP and CHOP versions offer different algorithms (Simplex, Perlin, Random, etc.).

  • Simplex: The default and generally the best looking/most performant for smooth continuous curves.
  • Random: Outputs pure white noise (completely disconnected random values per sample/pixel).

Key Parameters

  • Seed: Changing this gives you a completely different output while keeping the same “flavor” or character of noise.
  • Period: The “scale” of the noise.
    • Large Period: Smooth, slow rolling hills.
    • Small Period: Fast, jittery, tight oscillations.
  • Harmonics: Adds smaller, higher-frequency detail on top of the base noise. Higher harmonics = rougher/crunchier noise.
  • Amplitude: Scales the output values.
  • Offset: Shifts the output center up or down.

Animating Noise

To make the noise evolve over time:

  1. Go to the Transform page.
  2. In the Translate z parameter (usually tz), type the expression: absTime.seconds * 0.1
  3. The multiplier (0.1) controls the speed of the animation.

Common Uses

  • Noise CHOP: Driving the rotation of geometry, instancing coordinates, simulating wind/wobble on parameters.
  • Noise TOP: Building procedural clouds, water textures, or displacement maps. Using it over a generic geometry gives it an organic, undulating feel.

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