Experienced Country Inventor, Map Making Noob

[Mouse]

To add to what Pananacakes said - The height map itself isn't anything mysterious. Its just a bitmap that shows the sea as black, and the tops of the tallest mountains as white, with all the altitudes in between as blended shades of grey, rising from very dark at the bottom of the scale, towards white near the top of the scale.

You can make a really simple one and erode it in something like Wilbur to make it more realistic.

[waldronate]

By really simple, Mouse means starting with something like these:

coast.gif mtn0.gif mtn1.gif

and getting to this heightfield (in its simplest form, a heightfield is an image where the intensity of each pixel corresponds to the altitude of that point on the surface).

bump.jpg

in less than an hour. That heightfield was then colored and lighted in various ways and also projected into 3D for that one view