# Questions tagged [noise]

For questions about creating or working with noise functions (in 1D, 2D, 3D or more).

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### Why does increasing simplex noise dimension wash it out?

I just tried using this approach to create a tiling 2d simplex noise function with Gustavson's java implementation. The result tiled, but the texture seemed muddy / washed out. I decided to compare ...
1 vote
172 views

### Why the gradients generated in original Perlin Noise causing axis-aligned clumping?

I am learning Perlin Noise, the original version and the improved version. In the paper which Ken Perlin wrote in 2002. He said "The second deficiency is that whereas the gradients in G are ...
1 vote
45 views

### Are systems like double pendulum used for generating terrain?

Looking at the output of the angle of this double pendulum made me think this was a good candidate for generating realistic looking terrain profiles. I can't be the first to notice this so I was ...
119 views

### How to scale down noise frequency?

I'm making a space game and so far what I have is a system to generate spheres with noise on them, making them planets. I make a sphere, create noise data, write that data to an image file, and then ...
215 views

### Does MRG32k3a compare well with PCG and Xorshift256*?

I've been using standard 32-bit Xorshift in my GPU path-tracer for a while, following Nathan Reed's approach with hashed seeds and decorrelated state. I (finally) discovered today that Xorshift is ...
1 vote
75 views

### Confusion on the return value of turbulence of Perlin noise

turbulence function From my understanding, the turbulence in Perlin noise is to accumulate Perlin noise of different frequencies with different weights. Based on this understanding, the return value ...
1 vote
86 views

### Perlin noise is mysteriously ignored when the pattern is rotated 45 degrees

I am creating different coloring patterns for my CPU raytracer, such as checker, gradient, ring, stripe pattern etc. The problems started when I tried to create a perturbation pattern (of a subpattern)...
134 views

I'm slightly confused on how to create a simple noise function in a fragment shader if all fragment coordinates are integer therefore unable to interpolate between randomly generated values. What am I ...
1k views

### Analytical derivative of a 3D Simplex Noise field

I am using Simplex Noise to generate a 3D field. The specific implementation is FastNoise-SIMD. Assume I want to have a gradient (or derivative) for a sample at Sx, Sy, Sz in that field. Do I ...
162 views

### Perlin Noise, surface deformation NOT along the normal vector

I've a question about surface deformation using Perlin noise or Simplex noise. You can see everywhere on google images how these results look like, if you calculate a 2D / 3D noise and move the ...
521 views

### unwanted patterns in simplex noise

I want to create a "river biome" where there are rivers cutting to a flat land mass, to start I wrote a little js to generate a random height map (with simplex noise) but that's where I'm stuck. this ...
280 views

### Perlin Noise implementation looks blocky in WebGL2

I'm trying to implement Perlin Noise. Earlier I implemented it using HTML Canvas and then converted it to WebGL2 since I wanted a faster implementation. But the WebGL2 code has obvious edge artifacts ...
2k views

### What's a proper way to clamp dither noise?

When reducing color depth and dithering with a 2 bit noise (with n=]0.5,1.5[ and output=floor(input*(2^bits-1) + n)), the ends of the value range (inputs 0.0 and 1.0) are noisy. It would be desirable ...
774 views

### Nice way to make noise seamless (without tampering with the noise generator)

Here's the problem : I have multiple noise generators in my program I Can't change. Perlin Noise, Diamond Square, Voronoi, etc. Unfortunately for me, I want the noise to be tileable, no matter the ...
1 vote
206 views

### GPU Procedural placement - Creating evenly distributed sampling points

I am working on a procedural placement system on the GPU, inspired by the work done by Guerrilla Games in Horizon Zero Dawn: https://www.guerrilla-games.com/read/gpu-based-procedural-placement-in-...
1 vote
42 views

### Concerning the Procedural noise's function, how would you define a squared magnitude in plain word?

By googling, I have found some definition of squared magnitude about mathematical plane applied in the gaming field, but I am dubting this is what we would mean in the noise generation's field. ...
123 views

### How to approximate the heightmap of processed wood?

In the above image, you can see that there is some slight variation of the height of each wood plank. These variations do NOT come from the wood texture itself, but from the way it was cut, i.e if a ...
6k views

### How to modify Perlin (not simplex) noise to create continental like terrain generation

I have been playing around for a day with Perlin noise, and I am currently stuck. Most of the modifications I have made to the algorithm produce more or less the following: Now, this is a very good ...
233 views

### Noise shaping for dithering with gamma?

The context of this question is correct dithering of color with gamma correction. In dithering we add (shaped) noise $n$ to a signal $s \in [0, 1]$ based on a random variable $r \in [0, 1]$ s' = s +...
537 views

### Where do "fireflies" come from?

I'm using a renderer developed by other people, and I found there are fireflies. It is strange that in a completely diffuse scene, there are still fireflies presented. To my understanding, I think it ...
376 views

### How to create 2D (directional) noise?

I'm just getting started trying to understand noise generation algorithms. What I'm trying to achieve is to get a 2D (or 3D) grid of random directional vectors (again, 2D or 3D) according to a noise ...
94 views

### Finding the normals of a tileable 2D surface extracted from 4D space

If I use a 4D noise function which returns a noise value and a four-part analytically derived gradient vector, I can create a 2D tile which is seamless (i.e. the opposite edges match) through ...
125 views

### What noises can be sliced?

A well-known property of Perlin noise (with FBM) is that if you take a slice of it, the result is still Perlin noise. So, by taking successive slices of 4D noise, you get smoothly shifting 3D noise, ...
1 vote
1k views

### Procedural terrain: What's the best approach to calculate noise in the GPU?

A few years ago I started creating a procedural planet engine/renderer for a game in Unity, which after a couple of years I had to stop developing due to lack of time. At the time i didn't know too ...
708 views

### ScratchAPixel : Understanding how to use Perlin's permutations hash table

Consider this course : https://www.scratchapixel.com/lessons/procedural-generation-virtual-worlds/procedural-patterns-noise-part-1/creating-simple-2D-noise . In sub-part Introducing the Concept of ...
726 views

### What might be causing these artifacts in 5D & 6D simplex noise?

I've been working on writing functions for 5 and 6 dimensional simplex noise, working off FastNoise's 4D function as a base. 2D, 3D and 4D noise all follow a very similar and recognizable pattern ...
619 views

### Creating a gently moving 2D fog effect

I am trying to create a fog-like effect, similar to that found using perlin noise. I know where I can find information about that effect, but it's harder for me to tell if it's an efficient route for ...
1k views

### What is the basic idea of denoising?

When doing random sampling, you can get noisy results if you don't use enough samples like in the shadows below. I know that if you use high frequency noise (aka blue noise), the noise pattern can be ...
537 views

### Help understanding Perlin Noise

I am following this tutorial: Understanding Perlin Noise | Blog To understand Perlin Noise. In particular, right now I am focusing on the following code section: ...
1 vote
505 views

### Structural artifacts in ray jitter

I recently set up temporal super-sampling in my path-tracer, and now I'm trying to improve early samples by adding random offsets between -[PIXEL_WIDTH] and +[PIXEL_WIDTH] to each initial ray position....
231 views

### Is it possible to directly generate mipmap levels of perlin noise?

Say I'm generating some texture using perlin noise (or simplex noise, or any similar noise). Then I generate mipmaps to obtain minified versions of that texture... My question is if it is possible to ...
603 views

### What's the nature of Monte Carlo noise?

Monte Carlo rendering is just a process of sampling and reconstruction to evaluate the rendering equation. Why is it called noise rather than error?
57 views

### How to create a noise model with a constant PSNR?

My goal is to create a noise model so that the PSNR of the noisy image compared to the original is some pre-defined constant $\alpha$. This means the mean squared-error will also be a constant. My ...
250 views

### Downscaling by skipping rows and columns – any example images?

I'm about to implement downscaling on a microcontroller. Source resolution is e.g. 720x576 (the 576i PAL resolution, other one possible: 480i, NTSC resolution), destination is 32x16. The goal is to ...
347 views

### Perturbed image texture implementation from renderman language

I am trying to implement (in C#) an image perturbation algorithm presented in the book "Texturing and modeling - K. Perlin et al" (page 91 if anyone has it), which distorts an image. The following ...
1 vote
54 views

### How do you sample an analogue image and store it in a true-colour frame buffer? [closed]

I really cannot get my head around on this issue - how does an analogue image is sampled and then stored in a ture-colour frame buffer (e.g. in a camera) and how do you prevent noise when you do so? ...
3k views

### benefit of perlin noise over value noise

While investigating the inner workings of perlin noise, I wondered why one would use perlin noise instead of simple value noise. As far as I understand it right, the following applies: Perlin noise ...
4k views

### Why does my Perlin Noise look "blocky"?

I tried to implement Perlin Noise by myself using just the theory (following flafla2.github.io/2014/08/09/perlinnoise.html). Unfortunately I was unable to achieve the look of the "original" Perlin ...
4k views

### What makes a good permutation table?

I'm implementing improved Perlin noise. Its key feature for randomisation is the hardcoded permutation table, which gives essentially random but reproducible gradients at the cells of the grid. The ...
2k views

### How does a 2D Fourier Transform of an image work?

I understand how a 1D Fourier transform separates a signal into its component frequencies, but I'm having difficulty understanding how a 2D Fourier transform affects a 2D image. From another question,...
4k views

### How can I generate procedural noise on a sphere?

I would like to generate procedural noise on the surface of a sphere (e.g. to procedurally generate planets or marble-textured balls). Of course, I could just take a standard noise algorithm and map ...
915 views

### Why is it twice as expensive to make a noise function that can be tiled?

I've seen in several places that making Perlin noise loop seamlessly requires calculating it twice in slightly different ways, and summing the two results. This Perlin noise math FAQ gives a formula: ...