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Topic: Perlin noise

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	libnoise: Glossary
		A noise module that indicates how to combine the output values from the source modules that are connected to a selector module.
		A type of coherent noise that is the sum of several coherent-noise functions of ever-increasing frequencies and ever-decreasing amplitudes.
		A noise module that is used as a source of output values for another noise module.
	libnoise.sourceforge.net /glossary/index.html (1442 words)

	Perlin Noise (Turbulence)
		Perlin noise can be defined in any dimension, most common dimensions are 1 to 4.
		For the rest of this discussion the Perlin noise functions will be referred to as Noise(x) of a variable x which may a vector in 1, 2, 3 or higher dimension.
		Perlin noise can be created in 3D and higher dimensions, unfortunately it is harder to visualise the result in the same way as the earlier dimensions.
	local.wasp.uwa.edu.au /~pbourke/texture/perlin (1214 words)

	perlin at Programmers Heaven
		Perlin noise was invented by Ken Perlin, who won an Oscar award for it.
		One major disadvantage of the perlin noise function is that it is extremely slow for higher dimensions.
		I made a 3D perlin noise function and rendered it on a 2D texture map while moving along the z-axis, this had the effect of a pulsating map.
	www.programmersheaven.com /2/perlin (1243 words)

	Random Numbers, Probability, Perlin Noise at daniel shiffman
		Perlin noise (invented in the 1980s by Ken Perlin), however, allows us to produce a naturally ordered (”smooth”) sequence of numbers.
		The noise function is different from random, however, in that Perlin noise is defined in an infinite n-dimensional space (Processing can compute noise for 1, 2, and 3 dimensions).
		Two dimensional noise works in much the same, only, instead of calculating noise along a one dimensional path (such as time), noise is calculated as a function of an x,y coordinate in a two dimensional space.
	www.shiffman.net /teaching/the-nature-of-code/week-1 (1954 words)

	Processing 1.0 _ALPHA_ >> Language (API) (Site not responding. Last check: 2007-11-03)
		Perlin noise is a random sequence generator producing a more natural ordered, harmonic succession of numbers compared to the standard random() function.
		The main difference to the random() function is that Perlin noise is defined in an infinite n-dimensional space where each pair of coordinates corresponds to a fixed semi-random value (fixed only for the lifespan of the program).
		The actual noise is structured similar to an audio signal, in respect to the function's use of frequencies.
	www.architecture.yale.edu /873b/reference/noise_.html (345 words)

	Perlin noise - Wikipedia, the free encyclopedia
		Perlin noise is a function which uses interpolation between a large number of pre-calculated gradient vectors to construct a value that varies pseudo-randomly over space and/or time.
		He won a special Academy Award for Perlin noise in 1997, although Tron was denied the 1982 Academy Award for visual effects, because it "cheated" by using computer-generated imagery.
		Perlin noise is widely used in computer graphics for effects like fire, smoke, and clouds.
	en.wikipedia.org /wiki/Perlin_noise (316 words)

	Macromedia - Developer Center : Generating Perlin Noise with Director MX
		This is accomplished by using the same noise pattern at several different "octaves"—meaning that the texture repeats a different number of times depending on which layer it's on.
		Perlin texture mapping in two- and three-dimensional space is an effective technique for generating many different effects.
		Perlin Noise by Hugo Elias (cited November 21, 2002).
	www.adobe.com /devnet/director/articles/perlin_noise.html (2020 words)

	The Perlin noise math FAQ
		Perlin noise is function for generating coherent noise over a space.
		Coherent noise means that for any two points in the space, the value of the noise function changes smoothly as you move from one point to the other -- that is, there are no discontinuities.
		The problem with Perlin's implementation on its own was that that reading the descriptions of the math published on Perlin's website was a bit like reading Greek -- it took me about a week of reading his code and notes to figure out the actual geometric interpretations of the math.
	www.cs.cmu.edu /~mzucker/code/perlin-noise-math-faq.html (2639 words)

	Full Contact Wallpaper
		The Perlin noise function is generated as a rectangle of shades of grey.
		The noise function is then 'applied' to a colored rectangle; the color becomes equivalently darker or lighter corresponding to the different shades of grey.
		The Perlin noise function was invented by Ken Perlin in the mid 1980s.
	www.peak.org /~jeremy/possomery/noise (1008 words)

	Gamasutra - Features - "A Real-Time Procedural Universe, Part 1: Generating Planetary Bodies" [03.02.01]
		Each time through the loop, the coordinates passed to the noise function are scaled up by a certain factor and sent to the noise function, whose output is scaled down by a certain factor before adding it to the fractal sum.
		Because the noise function will return the same result for the same coordinates every time, you are essentially adding different parts of the same image to itself at different scales using different weights.
		The routine could be sped up using 2D noise and passing it latitude and longitude, but that would cause the terrain features to be compressed up near the poles, and a discontinuity would exist where the longitude wrapped around from 360 degrees to 0 degrees.
	www.gamasutra.com /features/20010302/oneil_02.htm (1689 words)

	Perlin Clouds
		These clouds were generated by using a three dimensional Perlin noise function.
		When noise is added to more noise at successively smaller scales, it creates a new kind of noise that, while still random, has an overall structure to it (see below).
		This is called Perlin noise, pink noise, or fractal noise.
	iat.ubalt.edu /summers/math/perlin.htm (283 words)

	Perlin Noise
		They show the component noise functions that are added, the effect of the persistence value, and the resultant Perlin noise function.
		If you are using the perlin noise function to render an image to the screen, there will come a point when an octave has too high a frequency to be displayable.
		Since all the noise functions are essentially the same, except for the values of those three big prime numbers, you can keep the same code, but simply use a different set of prime numbers for each.
	freespace.virgin.net /hugo.elias/models/m_perlin.htm (2736 words)

	libnoise: Tutorial 4: Modifying the parameters of the noise module
		For this tutorial, it is helpful to understand what exactly Perlin noise is — it's the sum of several coherent-noise functions with ever-increasing frequencies and ever-decreasing amplitudes.
		Beyond a certain number of octaves (determined by the resolution of the terrain height map), the frequency of the Perlin noise is greater than the resolution of the height map and you are doing more work than needed, for no effect.
		This will generate Perlin noise with a persistence value of 0.5, which is the default.
	libnoise.sourceforge.net /tutorials/tutorial4.html (714 words)

	3.4 Noise (Site not responding. Last check: 2007-11-03)
		Noise functions are useful in many situations, for instance, to give a surface an organic appearance.
		A cheaper noise function that can replace Perlin noise in some circumstances is provided by linnoise, which just linearly interpolates cellnoise.
		The worley and perlin functions, as well as related functions such as turbulence, may compile to a large number of instructions on backends which do not have a hash function or noise built in (which is all of them at the time this was written).
	libsh.org /ref/online/onlinese15.html (581 words)

	Hardware Perlin Noise Demonstration
		Perlin noise can be used to make some very impressive looking cloud effects, but at a substantial cost of processing power.
		Perlin Noise: this pattern was generated by multi texturing the base noise.
		Perlin Noise: each layer was offset differently to produce this pattern.
	dunnbypaul.net /perlin (1079 words)

	perlinNoise (BitmapData.perlinNoise method) -- Version 8
		Perlin noise has been described as a "fractal sum of noise" because it combines multiple sets of noise data with different levels of detail.
		Perlin received an Academy Award for Technical Achievement for the Perlin Noise function in 1997.
		The Perlin noise function is a mapping function, not a true random-number generation function, so it creates the same results each time from the same random seed.
	livedocs.macromedia.com /flash/8/main/00001963.html (760 words)

	Musgrave (Site not responding. Last check: 2007-11-03)
		A:M Noise function names where given before the procedural texture field of research had cristalized a naming convention so they do not always concur with other names around (see my digression about Noise function naming).
		Fractal Perlin is a different way to combine the different detail overlays together relative to the folding of the result.
		And the Offset is relative to the noise output function.
	www.ypoart.com /Downloads/Musgrave.htm (1351 words)

	CGArena : Volumetric Shader through Mental Ray
		It is a 4D Perlin noise, that is, a Perlin noise that changes with time.
		Perlin noise generates random numbers with a smooth transition between values, so that is what we use.
		The output value of the noise is the index to the ramp, so a low density value will correspond to the darker and redder values of the ramp, while higher density values will correspond to the lighter values of the ramp.
	www.cgarena.com /freestuff/tutorials/maya/shadertips/index3.html (930 words)

	Flash8 Perlin Wood Texture \| connectedpixel.com
		It seems that the first time the perlin noise is used in a movie, it takes a long time.
		Perlin noise is supposed to have a parameter called persistance that is used to control how the amplitude decreases with each perlin octave.
		Presumably, the Flash perlin function uses a persistance of 0.5, which seems to be the default in the perlin documentation I've read.
	www.connectedpixel.com /blog/texture/wood (915 words)

	flipcode - Perlin Noise Class
		I know there already is a Perlin noise function on the COTD collection, but this one serves a specific purpose.
		You construct an instance of Perlin as follows: Perlin *perlin = new Perlin(4,4,1,94); The first parameter is the number of octaves, this is how noisy or smooth the function is. This is valid between 1 and 16.
		There is a document by Perlin at http://mrl.nyu.edu/~perlin/paper445.pdf that improves on his original noise.
	www.flipcode.com /cgi-bin/fcarticles.cgi?show=64126 (1268 words)

	[No title]
		Noise is band-limited - almost all of its energy (when looked at as a signal) is concentrated in a small part of the frequency spectrum.
		The presence of this linear term causes the derivative of the Noise function to be discontinuous at cubic cell boundaries.
		Previous implementations of Noise, since they were defined on a cubic grid, required a successive doubling of the number of grid points that need to be visited, for each increment in the number of dimensions n.
	www.cs.unc.edu /~olano/s2001c24/ch09.html (4066 words)

	Pocketmoon
		This article discusses Perlin Noise and it's use in Terrain Generation and is based on the published code found in 'Textures and Modelling - A Procedural Approach' by Ebert, Perlin, Musgrave[?].
		The noise grid could represent the height values at 100-meter intervals with points in between being interpolated.
		What Mr Perlin proposed was that by layering multiple noise values together, using a grid at different frequencies for each noise value, things began to look 'natural'.
	baddoggames.com /planet/mft.htm (909 words)

	World Machine Device Reference
		Perlin Noise is a noise function developed by Ken Perlin.
		By layering multiple perlin noises at different frequencies and amplitudes, fractal noise functions that look to varying degrees like mountains can be created.
		Stabilized noise refers to whether or not the noise should be rescaled to fill the entire height range of the terrain quad.
	www.world-machine.com /DeviceRef.html (5384 words)

	CMPS 260 Project Procedural Textures - Perlin Noise
		I try to apply 4D Perlin Noise Functions(Animated 3D Textures) and find that it involves too expensive computation which is not suitable for real time animation.
		Perlin Noise Functions, utilize general random number generators, can create patterns with fractal features which exhibit the same pattern of large and small variations.
		Noise Function is simply a seeded random number generator.
	www.soe.ucsc.edu /classes/cmps260/Spring02/submit/weishen/html (660 words)

	Gamasutra - Features - "Real-Time Procedural Texturing Techniques Using MMX" [05.01.98]
		The number of iterations of Perlin's noise in the fBm are known as "Octaves".
		The derivative of a 3D Perlin noise function generates a random vector field, which can be used to perturb the object's normals.
		Using the Perlin noise function as a building block, wood, marble and grass textures were developed.
	www.gamasutra.com /features/19980501/mmxtexturing_01.htm (5945 words)

	Perlin Noise tutorial - Part 1 - The theory
		The sky is an almost-classical mapping of a 2D Perlin Noise.
		Perlin functions have a random fractal structure: this is the basis of their "natural" aspect.
		In Ken Perlin's approach (bottom curve of Figure 4), instead of randomising the amplitude of each bump, the slope at the zero points is randomised, and the values in-between are interpolated, so that the sub-functions match from one segment to another.
	www.mandelbrot-dazibao.com /Perlin/Perlin1.htm (1400 words)

	Noise Functions Naming Conventions (Site not responding. Last check: 2007-11-03)
		The native noise functions available in A:M are derived from this article and the names given to them also are derived from their implementation in this article.
		It folds the values of the Noise function at half its value range and scale the result to cover the whole 0 to 1 range.
		The alternative implementation of the Perlin and Sine I provide are named Fractal Perlin and Fractal Sine because the folding and the sine transformation is applied to the result of the fractal sum while the A:M implementation applies the folding and the sine transformation before fractilizing them.
	www.ypoart.com /tutorials/Materials-Names.htm (655 words)

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