Prototype a procedural heightfield before you build it in World Machine (world-machine.com). Drag the sliders and watch the terrain, its slope and its drainage follow. Roll a ball down it, make it rain, then bake it to a grid and erode it into river valleys.

Want to make this yours?

Remix "Terrain Workbench" into your own editable copy — tweak it, share it, make it yours.