Chapter 1. An Guide to the different Views

The different views/projections themselves should be self-explanatory. The "Fast Wireframe" thing might not be so, here's a short explanation: The default views all operate on the height field data directly and are designed to give good quality previews. When you select the "Fast Wireframe" option, terraform builds an index of the actual triangles making up your height field at the given resolution. This makes redrawing much faster, making it possible that you can rotate this preview by clicking and dragging your mouse.

When you're in "Fast Wireframe" mode, the 2DPlane, 3DHeight and 3DLight views will be shown unaltered while the 3DWire view will switch to the fast wireframe mode.

Generally, the height fields are much more fractal/rough than you would think from looking at the wireframe. The Wireframe view modes are really just an approximation of the general terrain type. The "Grayscale" colormap with "3D Light" view is the view type which best shows the terrain roughness. Export a few height fields to PovRay to get a feel for this.