Terragen - Terragen is a scenery generator, created with the goal of generating photorealistic landscape...
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
World Machine - Command powerful tools like erosion and advanced colormaps to create terrain heightmaps, meshes, and textures for your game or 3D scene. Download for Free!
Cinema 4D - Cinema 4D is a 3D modeling, animation, motion graphics and rendering application.
Picogen - The homepage of the free (as in freedom), GPL-licensed Terrain Synthesizer and Renderer named 'picogen'
V-Ray - Learn why V-Ray for 3ds Max’s powerful CPU & GPU renderer is the industry standard for artists & designers in architecture, games, VFX, VR, and more.