Okay, really, it's a little too fun to be able to create virtual landscapes like this on my wee little laptop. This is the sort of thing that used to require a supercomputer or an advanced degree in videogame design.

But here it is, surprisingly easy to do, with a free program called Terragen. It renders the sun, the atmosphere, the clouds, the water, and the terrain, from a particular camera position. All of those settings are scriptable, too, so you can create animations where you change the camera position, height of the sun, etc, over time.

Future versions of the program will allow creation of trees and vegetation, proper water features (like waterfalls), and user-created objects-- houses, cows, astronauts. For a budding theme park designer like myself, this promises all kinds of fun!