Procedurally-generated British countryside

Developer Big Robot is making an open-world game named Sir, You Are Being Hunted, for which it is required that swathes of convincing British countryside be generated on-the-fly.

I've worked on a number of procedural world generation tools before, but this particular engine is unique in that the intention was to generate a vision of "British countryside", or an approximation thereof. To approach this we identified a number of features in the countryside that typify the aesthetic we wanted, and seem to be quintessential in British rural environments. Possibly the most important element is the 'patchwork quilt' arrangement of agricultural land, where polygonal fields are divided by drystone walls and hedgerows. These form recognisable patterns that gently rise and fall across the rolling open countryside, enclosing crops, meadows, livestock and woodlands. This patchwork of different environmental textures is something that is very stereotypically part of the British landscape. I looked for a mathematical equivalent we could use to simulate this effect and quite quickly decided upon using Voronoi diagrams.

I feel compelled to offer this aerial photograph of Sark, by Phillip Capper (cc), which always looked to me like someone just plopped a gigantic SIGGRAPH paper in the middle of the sea.