Hi Marko,
Can you split each extract separately and then tell mkgmap to produce a map from the tiles generated by the three splitter runs?
Good idea, thanks. Generation seems to have worked, at least combining Finland and Germany. When adding US, it complained "map area too small to split". Will have to check that, maybe trying another split run on the US map with different parameters. Now downloading the result from my server and will test it on the gps device then later.
You could use my hand-made areas.list for Finland. It tries hard to get a nice generate-sea. It also avoids splitting the Lake Päijänne multipolygon. One of your tile borders slices the lake. The tile border should be a little more west near the line Jämsä-Kuhmoinen-Padasjoki.
That would be useful. Do you have it online somewhere? Or could you send it in a personal email? Thanks, Dominik