Here is a script I picked up from a Russian guy at GimpChat via http://master-gimp.ru/3d-map-generator- ... tu-v-gimp/. It's a great script, it will call for specific patterns which are included in the download file, however any can be used for extrude and overlay, also users may not want to include the map mesh in the final image, it gives a separate layer as option. NB while I had this installed I could not use GnuTux's 3D Extrusion script, it wouldn't show in my filters list.
If any clever script writer could even improve this - fantastic.
changes made to script were to prevent it interfering with GnuTux's 3d Extrude and to remove the script from the top line of the menu-bar
put the entire [3d Map Generator brushes folder] in your brushes folder
put the entire [3d Map Generator patterns folder] in your patterns folder
put the script in your script folder or replace your existing 3d-pattern generator script
refresh your brushes, patterns and scripts Menu Location is Script-Fu/3D Map Generator
use the script to create your own fantasy world/Island