Adjusting the sun location
To adjust the sun location in order to view the terrain in different
lighting conditions, hold the 'alt' key down, and drag the mouse with
the right button held down.
Auto create land
Press 'Ctrl-F' to make high areas land and low areas water.
After painting in oceans, rivers, or other features that may result in
rough shorelines, hit 'Ctrl-S' (or the smooth button) to smooth out the
shorelines. You may select an area to smooth only the shorelines
in that area.
Hint: To quickly select a feature such as a river, simple double click
it in selection mode
The thin tool is very handy for creating features such as narrow
rivers, or pathways. To use it, pain a river or pathway, then
select it (by double clicking it in face mode) and then use the thin
tool (Shortcut is Ctrl-T by default).