How is a 3d perlin noise function used to generate terrain?

terrain procedural-generation minecraft perlin-noise
Xavier picture Xavier · May 23, 2011 · Viewed 12k times · Source

I can wrap my head around using a 2D Perlin noise function to generate the height value but I don't understand why a 3D Perlin noise function would be used. In Notch's blog, he mentioned using a 3D Perlin noise function for the terrain generation on Minecraft. Does anyone know how that would be done and why it would be useful? If you are passing x, y, and z values doesn't that imply you already have the height?

Answer

Oliver Charlesworth picture Oliver Charlesworth · May 23, 2011

The article says exactly why he used 3D noise:

I used a 2D Perlin noise heightmap... ...but the disadvantage of being rather dull. Specifically, there’s no way for this method to generate any overhangs.

So I switched the system over into a similar system based off 3D Perlin noise. Instead of sampling the “ground height”, I treated the noise value as the “density”, where anything lower than 0 would be air, and anything higher than or equal to 0 would be ground.

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