Questions tagged [noise]
For questions about creating or working with noise functions (in 1D, 2D, 3D or more).
44 questions
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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 ...
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Does the original Perlin noise ever have any advantage over Simplex noise?
Perlin noise is one of the most popular procedural noise functions. Perlin later developed Simplex noise which improves on some of the shortcomings of Perlin noise, notably its inefficiency in higher ...
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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
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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 ...
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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 ...
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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 ...
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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 ...
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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)...
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Noise and fragment shader
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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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-...
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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.
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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 ...
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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 ...
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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 +...
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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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:
...
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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....
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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? ...
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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 ...
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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 ...
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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 ...
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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,...
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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 ...
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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:
...
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Is all grid based noise inevitably anisotropic?
I'm interested in how this applies to higher numbers of dimensions too, but for this question I will focus solely on 2D grids.
I know that Perlin noise is not isotropic (direction invariant), and ...
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