Questions tagged [noise]

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

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44 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 ...
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29 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 ...
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16 views

Create a TV noise effect

I am interested in reverse engineering a video effect, that is composed of different parts. I'll try to split it into different questions as advised on StackExchange Meta. This is the example image: ...
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1answer
61 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 ...
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1answer
56 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 ...
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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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38 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. ...
4
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1answer
78 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 ...
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1answer
278 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 ...
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0answers
131 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 +...
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297 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 ...
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2answers
107 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 ...
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1answer
76 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 ...
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59 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 ...
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1answer
68 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, ...
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1answer
634 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 ...
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2answers
287 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 ...
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2answers
904 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 ...
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1answer
327 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 ...
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1answer
323 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 ...
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1answer
258 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....
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1answer
143 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 ...
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3answers
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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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3answers
4k 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 ...
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1answer
337 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: ...
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0answers
581 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?
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48 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 ...
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2answers
151 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 ...
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354 views

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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1answer
368 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 ...
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51 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? ...
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1answer
2k 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 ...
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1answer
3k 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 ...
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2answers
2k 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 ...
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1answer
278 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 ...
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1answer
578 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,...
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1answer
369 views

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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1answer
532 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: ...
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1answer
3k 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 ...
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1answer
2k views

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 ...