The Noise modifier modulates the position of an object's vertices along any combination of three axes. This important animation tool simulates random variations in an object's shape.
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Modify panel > Make a selection. > Modifier List > Object-Space Modifiers > Noise
Using a fractal setting, you can achieve random, rippling patterns, like a flag in the wind. With fractal settings, you can also create mountainous terrain from flat geometry.
You can apply the Noise modifier to any kind of object. The Noise gizmo changes shape to help you visualize the effects of changing parameter settings. The results of the Noise modifier are most noticeable on objects that have greater numbers of faces.
Most of the Noise parameters have an animation controller. The only keys set by default are for Phase.
Plane with no noise applied
Adding texture to the plane creates a calm sea.
Plane with fractal noise applied
Textured plane with noise creates a stormy sea.
Procedures
To apply noise to an object:
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Select an object and apply the Noise modifier. To animate, move to a nonzero frame and turn on 
(Auto Key). - In the Parameters rollout
Strength group, increase Strength values along one or more of the three axes. You begin to see noise effects as the strength goes up.
- In the Noise group, adjust Scale. Lower values increase the dynamics of the Strength settings, making the effect more obvious. See Noise group, below, for other options.
If you've animated this procedure, you can change parameters as the animation runs to see the effects.
For another source of noise effects, go to the sub-object level of the Noise modifier and transform the gizmo and center of the modifier.
To create terrain effects:
- Apply the Noise modifier to the object.
- In the Parameters rollout Noise group, turn on Fractal.
Roughness and Iterations settings are now available.
- Increase Strength on the Z axis and adjust other parameters.
Once you have a base terrain, you can select sub-objects with Edit Mesh and apply Noise to grow mountains in a smaller region. You can also apply a second Noise modifier to amplify the first one.
When set for Fractal, the Noise modifier produces a random fractal noise that creates a variety of topological and terrain effects. You can animate these effects or use them to model static landscapes and other complex forms.
The following steps assume you begin with a broad object like a multi-segment box lying on the XY plane.
Interface
Modifier Stack
- Gizmo/Center
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You can move, rotate, or scale the gizmo and center sub-objects to affect the noise. You can also animate the sub-object transforms.
For more information on the stack display, see Modifier Stack.
Parameters rollout
Noise group
Controls the appearance of the noise, and thus its effect on the physical deformations of the object. By default, the controls are inactive until you change the settings.
- Seed
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Generates a random start point from the number you set. Especially useful in creating terrain, because each setting can produce a different configuration.
- Scale
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Sets the size of the noise effect (not strength). Larger values produce smoother noise, lower values more jagged noise. Default=100.
- Fractal
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Produces a fractal effect based on current settings. Default=off.
If you turn on Fractal, the following options are available:
- Roughness
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Determines the extent of fractal variation. Lower values are less rough than higher values. Range=0 to 1.0. Default=0.
- Iterations
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Controls the number of iterations (or octaves) used by the fractal function. Fewer iterations use less fractal energy and generate a smoother effect. An iteration of 1.0 is the same as turning Fractal off. Range=1.0 to 10.0. Default=6.0.
Strength group
Controls the magnitude of the noise effect. No noise effect occurs until some strength is applied.
- X, Y, Z
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Set the strength of the noise effect along each of three axes. Enter a value for at least one of these axes to produce a noise effect. Default=0.0,0.0,0.0.
Animation group
Controls the shape of the noise effect by overlaying a sine wave for the noise pattern to follow. This keeps the noise within bounds, dampening random extremes. When Animate Noise is turned on, these parameters influence the overall noise effect. However, you can animate Noise and Strength parameters independently; these do not require Animate Noise to be on during animation or playback.
- Animate Noise
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Regulates the combined effect of Noise and Strength parameters. The following parameters adjust the underlying wave.
- Frequency
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Sets the periodicity of the sine wave. Regulates the speed of the noise effect. Higher frequencies make the noise quiver faster. Lower frequencies produce a smoother and more gentle noise.
- Phase
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Shifts the start and end points of the underlying wave. By default, animation keys are set at either end of the active frame range. You can see the effect of Phase more clearly by editing these positions in Track View. Select Animate Noise to enable animation playback.