Using OSM maps on Garmin handhelds.

The scenario is simple: you spend a not insignificant amount of money on a Garmin GPS unit, then travel and find that you don’t have maps for that region, and Garmin charges quite a lot of money for something that you didn’t know you were missing. So you then search the interwebs for solutions, and find lots of seemingly complicated methods of loading maps from Open Street Maps (OSM).

From what I understand, the OSM data needs to be packaged in an image file (*.img) for the Garmin to read it. This is easiest done by using an existing web service, a list of which are on the Wiki. I decided to use BBBbike because it has the territories that I am interested in. The packaging is done server-side, and it sends you an email with a download link, so you will need to put your email address in, choose a map type and then select the part of the map you want. There is no political boundary map, so I used the freeform to select the rough area I wanted. You then have to select the map type, there is a link with examples, there are a couple of cycling maps which look superb, but I am using this Garmin for hiking, so I chose the Open Topo Map (there are also two text formats, either should work on newer units, I tried both Latin and Unicode). I have not received any unsolicited email from this service. A few minutes later you will get an email with a download link.

  1. Make a folder on your local drive for Garmin/GPX stuff.
  2. Decompress the downloaded file to your new folder. Rename the file with something useful (i.e. Scotland_Open_Topo.img)
  3. Either format a blank MicroSD card (FAT or FAT32) and create a /GARMIN folder on it, or go to your existing SD card and open the /GARMIN folder.
  4. Move the new *.img file to your /GARMIN folder.

I then inserted the card in the device, connected it to the computer and checked that the map is correctly loaded on Garmin BaseCamp. The maps are then turned on/off from the device in Settings/Map.

The maps I downloaded are routable vector maps with topographic details. They are better than the stock Garmin maps.

Tobias Feltus: