Noise generator

Minecraft uses several examples of noise generators, specifically those making use of gradient noise, for the generation of terrain alongside other features.

Specifications
Noise generators are defined by the following parameters:


 * Octaves:
 * Period:
 * Factor:
 * Offset:

Major noise generators
These are used for defining the shape of generated terrain itself.

Low noise
Low noise is one of the two main noise generators used for defining terrain shape. This noise generator, which uses Perlin noise, is one which is actually used as a heightmap.

High noise
This is identical to low noise, but is only used when selector noise is above a given threshold value.

Selector noise
Selector noise is a third important noise generator used for terrain generation. Selector noise, using Perlin noise, dictates which of either low noise or high noise is used for generating terrain at a given position - above 1 high noise is used, below 0 low noise is used, and values between 0-1 are linearly interpolated between the low and high noise values.

Depth noise
A rather insignificant noise generator, this uses Perlin noise to make terrain slightly more nuanced in general. The possible values it can have are tightly clamped to a thin set of values. It is also only defined for the X and Z axes.

Other noise generators
These noise generators are oriented to the generation of other world features.

Removed noise generators
These are no longer used in the current version of the game.