1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
.. _bpy.types.ShaderNodeTexNoise:
******************
Noise Texture Node
******************
.. figure:: /images/node-types_ShaderNodeTexNoise.webp
:align: right
:alt: Noise Texture Node.
The *Noise Texture* node evaluates a fractal Perlin noise at the input texture coordinates.
It can be used for a single Perlin noise evaluation, or for combining multiple octaves
(layers) with increasingly finer detail.
Inputs
======
The inputs are dynamic: they become available if needed depending on the node properties.
Vector
Texture coordinate to evaluate the noise at;
defaults to *Generated* texture coordinates if the socket is left unconnected.
W
Texture coordinate to evaluate the noise at.
Scale
Scale of the base noise octave.
Detail
Number of noise octaves. This can have a fractional part, in which case a blend
is performed (e.g. a Detail of 2.5 results in a 50% blend between 2 and 3 octaves).
Roughness
Blend between a smoother noise pattern, and rougher with sharper peaks.
Lacunarity
The difference between the scale of each two consecutive octaves.
Larger values corresponds to larger scale for higher octaves.
Offset
An added offset to each octave, determines the level where the highest octave will appear.
Gain
An extra multiplier to tune the magnitude of octaves.
Distortion
Amount of distortion.
Properties
==========
Dimensions
The dimensions of the space to evaluate the noise in.
:1D: Evaluate the noise in 1D space at the input *W*.
:2D: Evaluate the noise in 2D space at the input *Vector*. The Z component is ignored.
:3D: Evaluate the noise in 3D space at the input *Vector*.
:4D: Evaluate the noise in 4D space at the input *Vector* and the input *W* as the fourth dimension.
.. note::
Higher dimensions corresponds to higher render time,
so lower dimensions should be used unless higher dimensions are necessary.
Type
Type of Noise texture, with different ways to combine octaves.
:fBM:
Fractal Brownian motion, produces a homogeneous and isotropic result.
Values from octaves are added together.
:Multifractal:
More uneven, varying by location similar to real terrain.
Values from octaves are multiplied together.
:Hybrid Multifractal:
Creates peaks and valleys with different roughness values, like real mountains rise out of flat plains.
Combines octaves using both addition and multiplication.
:Ridged Multifractal:
Creates sharp peaks. Calculates the absolute value of the noise,
creating "canyons", and then flips the surface upside down.
:Hetero Terrain:
Similar to *Hybrid Multifractal* creates a heterogeneous terrain, but with the likeness of river channels.
Normalize :guilabel:`fBM`
If enabled, ensures that the output values stay in the range 0.0 to 1.0.
If disabled, the range is at most -(*Detail* + 1) to *Detail* + 1 (smaller if *Roughness* < 1).
Outputs
=======
Factor
Value of fractal noise.
Color
Color with different fractal noise in each component.
Examples
========
.. figure:: /images/render_shader-nodes_textures_noise_example.jpg
Noise Texture with high detail.
.. list-table:: Different Noise types with the same parameters.
* - .. figure:: /images/render_shader-nodes_textures_musgrave_example-type-fbm.jpg
:width: 320px
fBM (fractal Brownian Motion).
- .. figure:: /images/render_shader-nodes_textures_musgrave_example-type-multifractal.jpg
:width: 320px
Multifractal.
* - .. figure:: /images/render_shader-nodes_textures_musgrave_example-type-hybrid.jpg
:width: 320px
Hybrid Multifractal.
- .. figure:: /images/render_shader-nodes_textures_musgrave_example-type-terrain.jpg
:width: 320px
Heterogeneous Terrain.
* - .. figure:: /images/render_shader-nodes_textures_musgrave_example-type-ridged.jpg
:width: 320px
Ridged Multifractal.
- ..
Notes
=====
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.
.. figure:: /images/render_shader-nodes_textures_noise_issue-constant-value.png
An example configuration where the noise evaluates to a constant value.
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.
.. figure:: /images/render_shader-nodes_textures_noise_1d-noise-plot.png
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.
- Evaluate the noise at a higher dimension and adjust the extra dimension
until a satisfactory result is achieved.
.. list-table::
* - .. figure:: /images/render_shader-nodes_textures_noise_issue-constant-value.png
Constant value issue.
- .. figure:: /images/render_shader-nodes_textures_noise_solution1-constant-value.png
Mitigating the issue by adjusting the scale.
* - .. figure:: /images/render_shader-nodes_textures_noise_solution2-constant-value.png
Mitigating the issue by adding an arbitrary offset.
- .. figure:: /images/render_shader-nodes_textures_noise_solution3-constant-value.png
Mitigating the issue by evaluating at a higher dimension.
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.
.. figure:: /images/render_shader-nodes_textures_noise_issue-banding.png
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.
.. figure:: /images/render_shader-nodes_textures_noise_solution-banding.png
Mitigating the issue by rotating the coordinates by an arbitrary amount.
|
