Terragen

Terragen is a powerful solution for building, rendering, and animating realistic natural environments. Create entire worlds from your imagination, or import real-world terrain data sets and use Terragen to create the most realistic visualizations possible. You control the weather, landscape, rivers, lakes and oceans, suns, moons and stars. With Terragen you have complete control over the shader networks used for terrains, textures, micropolygon displacements, clouds and object distributions.