噪波纹理着色器节点

噪波纹理着色器节点。

The Noise Texture node evaluates a fractal Perlin noise at the input texture coordinates.

输入是动态的，下面的输入端口会在选择的节点属性需要时出现。

矢量

Texture coordinate to evaluate the noise at; defaults to Generated texture coordinates if the socket is left unconnected.

Texture coordinate to evaluate the noise at.

比例|缩放

Scale of the base noise octave.

细节

Number of noise octaves. The fractional part of the input is multiplied by the magnitude of the highest octave. Higher number of octaves corresponds to a higher render time.

粗糙度

Blend between a smoother noise pattern, and rougher with sharper peaks.

畸变

畸变量。

规格尺寸

用于计算噪波的空间维度。

Note

Higher dimensions corresponds to higher render time, so lower dimensions should be used unless higher dimensions are necessary.

系数

Value of fractal noise.

颜色

Color with different fractal noise in each component.

高细节噪波纹理效果。

While the noise is random in nature, it follows a certain pattern that might not evaluate to random values in some configurations. For instance, consider the following configuration where a grid of objects have a material that evaluates a noise texture at their locations. One might expect the objects to have random values since they have different locations, but this is not the case.

It seems all objects have a value of 0.5. To understand why this happens, let us look at the following plot of a 1D noise texture.

A plot of a 1D noise with zero details and zero distortion.

The horizontal line denotes a value of 0.5 and the vertical lines denotes whole numbers assuming a noise scale of 1. As can be seen, the noise always intersects the 0.5 line at whole numbers. Since the aforementioned objects were distributed on a grid and have whole number locations, they all evaluate to 0.5. Which explains the issue at hand.

Generally, any discrete evaluation of noise at integer multiples of the reciprocal of the noise scale will always evaluate to 0.5. It also follows that evaluations closer to that will have values close to 0.5. In such cases, it is almost always preferred to use the White Noise Texture.

Regardless, one can mitigate this issue in a number of ways:

Adjust the scale of the noise to avoid aligning the noise with the evaluation domain.
Add an arbitrary offset to the texture coordinates to break the alignment with the evaluation domain.

Similarly, in other configurations, one might experience some banding patterns in the noise, where there are bands of high contrast areas followed by banding of low contrast areas. For instance, planar surfaces that are slightly tilted along one of the axis will have such a banding pattern.

An example configuration where the noise have a banding pattern.

This happens because the slight tilt along one of the axis causes values along the perpendicular axis to change very slowly making the grid structure of the noise more apparent. The easiest way to mitigate this issue to rotate the coordinates by an arbitrary amount.

Mitigating the issue by rotating the coordinates by an arbitrary amount.