About 6 months ago I started researching the question of "how to get Garmin compatible maps to use in Russia and Central Asia ?".

For the Central and South American legs of our 2009/2010 journey through The Americas I relied on a collection of gmapsupp.img files that I found on various websites ranging from cgsmapper.com to smellybiker.com. This worked but was a little adhoc.

This time around I wanted to be more organized. Which means that I would like to.

  • have a set of routable maps that covered our entire route.

  • view the maps on, and plan routes with, Garmin's Basecamp program (note I am a Mac user)

  • collect and store GPS tracks and waypoints and eventually publish those on my website.

As I started researching it became clear that the OpenStreetMap(OSM) project would be a good source of maps if only I could figure out how to use them on a Garmin GPS.

OSM to Garmin for MAC Users

The OSM world map is made up of a large number of rectangular regions. Getting the OSM data for ones area of interest requires making a selection of some of those regions and the downloading of the OSM data for the selected regions. Thereafter one must convert that OSM data into a suitable Garmin format and finally that Garmin format must be installed so that Basecamp and/or your GPS unit can use it. In my research I found all kinds of alternatives for doing these steps, some worked, some did not (as far as I could tell) and most were complicated.

In the end I think I found a relatively simple process chain and toolset for doing what I needed.

This is how I get OSM data into a Garmin compatible map!

STEP 1 - Get your map in Garmin format

The first big hint came from this Horizonsunlimited.com page . It led me to garmin.openstreetmap.nl which does much of the heavy lifting.

On the garmin.openstreetmap.nl site start by selecting the map type, give your email address, enable manual tile selection and then on the map of the world select the tiles/rectangles that cover your area of interest.

Once all the tiles of interest are highlighted click the Build my map button. The website will then go away and build your map.

You will receive two emails from garmin.openstreetmap.nl.

  • The first will give you a link to a page that will tell you where your job is in the waiting list.

  • The second will come when your map is complete and it will contain a link to a page from which you can download some files associated with the completed map. Some of the files are zipped so after unzipping where appropriate you will have the following.

    an installer for windows which will make the map available in Mapsource or Basecamp
    which can be directly loaded onto a GPS or its microSD chip. If placed inside the GARMIN directory this map can be activiated on a Garmin device.
    OSM Generic routable.gmap
    On a Mac this file can be "installed" using the program Garmin MapManager.app, and thereafter is available in the Basecamp.app program.

STEP 2 - Give an OSM map a meaningful name (useful if you have more than one)

It is possible to stop at this stage of the process. After all you have one or more gmapsupp.img files that can be loaded onto a Garmin GPS and one or more maps called "OSM Generic routable" available in Basecamp.

The problem is that if you want to build more than one map using the process they will all have the same name, specifically OSM Generic routable. This is not very convenient if like me you want to build and manage 8-12 maps.

So the next step is to rename the maps to something more meaningful. For this you need a program called JaVaWa GMTK.app available from JaVaWa GMTK English site.

The process for renaming is straightforward.

  • Taking one OSM Generic routable.gmap at a time, install it using Garmin MapManager.app, and then close Garmin MapManager.

  • Open the map just installed in Garmin Basecamp.app and check that it is the map you thought it was. Then close Basecamp.

  • Open JaVaWA MTK.app. From the list of installed maps select the one just installed (which will be called OSM generic routable), click the Extra main menu option, and from the pop-up menu select the change name and ID.

    Give it any name you want and make sure that you give it a unique (across your selection of installed maps) FID.

STEP 3 - A Caveat:"segment code exists in other maps too"

I have noticed that when two or more maps created as above have OSM tiles in common (that is they cover overlapping segments of the Earth and they have all been installed by Garmin MapManager) the JaVaWa program reports an error which is described by the main menu Info option as Segment error: Segment codes exist in other maps too. . However, in my experience this does not impede the use of the offending maps.