I wonder what it would take to adapt a model like this to generate non-Earthlike terrain. For example, if you were using it to make planets without atmospheres and without water cycles, or planets like Io with rampant volcanism.
In practice you can use 2d generation on spheres with simple UV mapping techniques. Your pixel height becomes distance from the sphere origin.
Since 1996, Ken Perlin has published a whole bunch of extremely cool Java applet demos on his web page, which he uses to teach his students at NYU and anyone who wanted to learn Java and computer graphics. One of his demos was a procedural planet generator!
I learned a lot from his papers and demo code, and based the design of The Sims character animation system on his Improv project.
https://mrl.cs.nyu.edu/~perlin/ (expired https cert)
https://web.archive.org/web/20001011065024/http://mrl.nyu.ed...
Here's a more recent blog post about a new one using WebGL, Dragon Planet:
https://blog.kenperlin.com/?p=12821
Here's another blog post about how he's been updating his classic Java applets by rewriting them in JavaScript:
https://blog.kenperlin.com/?p=27980