Map generation tutorial

Hello, I’m looking for, and I can’t find, a guide that explains how to generate a *.img map like the ones at
They would be maps for a Garmin Montana.

I suppose it’s something like exporting OSM data and processing it with some program.

I’ve read the OSM wiki and this forum but I can’t find anything.
Can someone tell me where to look? If there is something published, of course.


Yes, that’s exactly what you do. Download or obtain an area of interest (many formats are available) as an .osm file and then process it using a Java program called mkgmap which, with the help of optional style sheets, will create a Garmin .img file that can then be read by your device.

Check out the documentation at the mkgmap site at and also the section in the OSM Wiki here:

If you want to create maps that involve large areas, you might have to resort to another program called Splitter that, as the name suggests, splits the data file into chunks that mkgmap can handle in a preprocessing step. Start by selecting a small area from the main OSM site: so you don’t have to resort to Splitter. That will come along later.

At, pan to your area of interest and click the Export button. Once you’ve done that click on Manually Select a Different Area and adjust the bounding box until you’re satisfied. Then click on the Overpass Api link to begin your download. The data will download as map.osm (or some other name of your choosing) which can be processed with mkgmap.

This is the way I obtain data for my maps but there are lots of other options.

Good luck

You can get a quite recent extract of the data from Geofabrik at Just download “iceland-latest.osm.pbf”.

Thank you for your answers. From what you say it seems simpler than I imagined.
I know Mkgmap slightly and used it a few times, I’ll have to study it to see if I can make a map.