How to split "not coherent" maps with the mkgmap splitter?

Hi everyone,

i just encountered a problem:
I try to make a map containing Germany, the Netherlands and Iceland. To do so, i downloaded the extracts for the three countries from the Geofabrik and combined them with osmconvert. The filesize is a reasonable 1.57 GB as a PBF-file. This file i feed to the splitter and it reads the whole input but the split result is way to small and only contains the Icelandic map. I think this is because the map is not coherent in its self and the splitter only works on the first encountered part of the map, is this case Iceland.

Is there any way to “tell” the splitter to work on the “other” data as well?

Thanks for any help!


you cannot join extracts again to one new one: the ways between this extracts will be still broken. You should create your own polygon and extract the area you need from a larger extract.

About the splitting problem: sounds like the bounding box of the data is wrong.


Hi Thorsten,

thanks, but the broken ways and relations at the borders won’t bother me, cause i don’t want to route over a border, so this doesn’t matter.

The other problem is, the map data for Iceland and “the rest” are separated “data islands” with nothing in between, so “my extract” would consist of two polygons - would this work?

I just want a map containing the data for Iceland and my homeland, i don’t want the data for the UK and the Atlantic ocean between them. But maybe i should simply create an own map for Iceland, put that on a separate memory card and than simply swap the cards when i arrive at the airport? :confused:

Just a guess, but you could try using the --mixed option for splitter.

You can create on polygon file with two polygons inside.

I personal would prefer 2 different maps.
I don’t know which GPS-device you have. I personal would prefer 2 different maps. On most Garmin GPS, you can copy both names with different names on the device. Else you can install the Maps in MapSource and export them as one gmapsupp.img, or use tools like gmt.
No need to swap the memory card, but that’s of course possible, too.


Thank you, i found out myself in the OSM-Wiki about poly-files. So i could cut the needed data out of an europe extract, but that would require to download the whole dataset. :confused:

I think, this is the method to use, cause i have an etrex Vista HCx, which only supports one gmapsupp.img file. :slight_smile:
I only have to be careful to use different map- and F-IDs for the different datasets, so gmt.exe will put the maps in one gmapsupp.img without errors and i have to provide a TYP-file for every single FID. This way i have to download a lot less data. :wink:

Thanks everyone!