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!
showFoto - ShowFoto is the standalone image editor of the digiKam project.
Vue - Create vast expanses of terrains, add trees, select the best point of view and render...
PixBuilder - Free Photo Editing Software for PC
Picogen - The homepage of the free (as in freedom), GPL-licensed Terrain Synthesizer and Renderer named 'picogen'
PhotoDemon - Lightweight portable BSD licensed photo editor for Windows focused on performance and usability.