Martin O'Leary not only made a cool fantasy map generator, he's giving away the source code and has described the process at a high enough level for an idiot like me to partly understand how it works.
I wanted to make maps that look like something you'd find at the back of one of the cheap paperback fantasy novels of my youth. I always had a fascination with these imagined worlds, which were often much more interesting than whatever luke-warm sub-Tolkien tale they were attached to.
At the same time, I wanted to play with terrain generation with a physical basis. There are loads of articles on the internet which describe terrain generation, and they almost all use some variation on a fractal noise approach, either directly (by adding layers of noise functions), or indirectly (e.g. through midpoint displacement). These methods produce lots of fine detail, but the large-scale structure always looks a bit off. Features are attached in random ways, with no thought to the processes which form landscapes. I wanted to try something a little bit different.
It's an odd feeling to look at these instantly-generated, detailed maps and realize that they represent nothing. I feel like I'm being wasteful pressing the "Generate high resolution map." The Uncharted Atlas is a twitterbot that posts a new map every hour.