Perlin Noise - Your New Best Friend

Perlin Noise is a technique to create natural looking textures and movements by using pseudorandom numbers that was designed by a rather clever computer scientist, Ken Perlin, who is a Professor at New York University.

Instead of trying to explain what it is and how it works (aka "reinvent the wheel"), I'll instead point you in the direction of Professor Perlin's own words. Read this; absorb this:

http://www.noisemachine.com/talk1/

So now that you're familiar with the basics and how things work, here are two more articles about how Perlin Noise can be used and the basic math behind it:

http://student.kuleuven.be/~m0216922/CG/perlinnoise.html
http://freespace.virgin.net/hugo.elias/models/m_perlin.htm

(If these articles are ever taken down, I'll write up something even better here when I have the time.)

Perlin Noise is a marvelous tool for modeling natural structures, as the field it generates is inherently procedural (so we can calculate things at any point simply knowing the seed) and fractal (like many natural structures). Once you're able to master Noise, you'll be able to master some very good-looking visualizations.

Now for my purposes, I took the Improved Noise function that Perlin wrote, himself, and ported it to PHP:

http://research.thenerdtank.com/therandomuniverse - Click on Perlin.class.txt

You'll also note that I put together two additional functions which come in handy when you quickly need less than 3 degrees of noise.

Using the code above, I was able to get the following results when creating an image:

Since the Perlin Noise function gives a number between -1 and 1, inclusive, the picture on the right is divided by two plus one (noise/2+1), where the picture on the left is its absolute value (|noise|).

Now, using this noise function, in our next article we're going to investigate how to decently simulate (for the sake of an RPG) the large-scale structure of the cosmos by modeling the layout of galaxy clusters.

Peace,
-Steve