This second map shows how I plan to export and later import regions between Opensimulator and L3DT. I've written a series of tutorials for doing this with Leveller (see https://asstnotesideas.blogspot.com/search/label/daylonleveller) but it's pretty much the same process with L3DT. In both cases you can import/export a rectangle of 1x1 or larger regions and if these are named correctly, the terrain editors will load those terrains in the correct spot.
For example, I could save the Northern Straight regions terrain as follows...
un-15 to ns_x0_y0.ter,
un-25 to ns_x1_y0.ter,
un-16 to ns_x0+y1.ter, and
un-26 to ns_x1_y1.ter
...and L3DT will load them correctly.
Now I'm using L3DT here for the changes because it's a bit better at doing finicky details on a 3D view. Leveller is far better at planning an original terrain set, and in fact the original of Urbania was done using Leveller. But rather than throw that away I've just re-used the terrains and OARs (in the case of the purple core area) instead, and that's why I'm using L3DT to make it a smooth transition from one region to another.
