Terragen

From GameStudio Wiki

Terrain exporting from Terragen

For exporting a heightmap from Terragen, save it to an image in BMP, PCX, or TGA format.

For exporting a shadow mapped terrain skin texture from Terragen, set the camera position in terrain units at 128,128,1024, the target at 128,128,0, and the zoom at 8. Now an image is rendered which can be directly saved and used as the skin for the terrain.

Terragen is free available at http://www.planetside.co.uk/terragen.