Ridged Perlin Noise

While doing research for the terrain editor I found a lot of different methods for creating noise. One of my favorite algorithms is “ridged fractal noise”. I haven’t found any examples of this in AS3 so I created my own version based on the Optimized Perlin Noise seen in the community before. I think the route of that source began with Ron Valstar’s AS3 version (@Sjeiti), then with a optimized version by @quasimondo, and further optimized with a haxe-version by Nicolas Cannasse. It was very easy to just add the ridged part to the noise generated. There is some source to look at in other languages such as C++, Java or C#. First some examples to see whats the characteristics of ridges. Some of them uses a Stok3d PhongShader created by @DerSchmale to add a nice depth:

Terrain | My favorite. Imagine using this with a voxelengine.



Trails | Put together in Photoshop to demonstrate the effect of the shader


Stone texture

It’s quite fun to search for new patterns by just adjusting the few parameters:

Make some noise

Try it out for yourself. I have limited the size of the bitmap to 200×200. It’s pretty optimized, but still to slow for large bitmaps. A Cool thing is that the swf is just 26 kB. Thanks @bit101 for MinimalComps.

Open editor

Here is a explanations for some of the parameters (I borrowed the descriptions from the reference of world-machine):

Offset: Offset determines at what elevation the fractal behavior begins to change its character.
Gain: A multifractal parameter, Gain typically controls the relative strength of the detailed versus smooth regions of the fractal. Low values are very smooth, while high values bring on the detailed nature more quickly.
Persistence: Controls the degree to which the strength of each layer of noise is reduced as they are layered together. Low persistence values produce very smooth terrains, whereas increasing the persistence produces more detail (and spikiness). Unlike a low octaves value, all layers of noise are still calculated when using a low persistence, so that terrain features are smoothly introduced as the value is increased.

If you’re interested, here is the source code for the noise generator (in Haxe).

In a terrain a heightmap with ridges is suitable for creating high mountains or sand dunes, which was my primary goal. Next step is to visualize it in 3d. The ridges does not look so good with a low poly mesh, so I have to look for a voxel-engine now.