Maps & Open Street Map

Maps are something you’re going to need when travelling or Geocaching. You can either use good old paper maps (which you should always take as a backup anyway), borrow a copy of an online map (France / UK) using a screen capture program, or purchase a map for your GPS. Most GPS vendors charge a substantial price for suitable walking maps on GPS, especially with topographic details includes (contour lines).  Perhaps it isn’t that much when you consider the cost of buying the same data on paper, or the cost of creating the information in the first place, but it always feels like a lot.  

OpenStreetMap has now become an excellent resource - as evidenced by the above animation and the fact that I haven’t bought an overpriced Garmin map for more than a decade.  In combination with freely available the NASA SRTM contour data, it has become practical to access online maps from a smartphone; or to download pre-rendered maps for your smartphone or GPS. 

OpenStreetMap Renderings

OpenStreetMap can be thought of as two things - the cartographic data and a rendering that's applied to the map data to make it human readable. There are a number of different renderings created by individuals and companies for a variety of different purposes (road, trail, sea etc).

For outdoor trail use the first good rendering I discovered was the OpenCycleMap, but more recently and (legend) have overtaken it in clarity and contrast.

World Wide OpenSteetMaps on your Garmin: Open MTB Maps

World Wide OpenSteetMaps on your Garmin: Open MTB Maps online rendering and downloadable files for Locus or Image raster


Modern android smartphones now have access to a number of mapping applications that can use online map services, or pre-downloaded map files when you're not going to have access to a cellphone signal.

I've found LocusMaps to the most capable, stable, and fairly simple to use (although it does have a steeper learning curve than Google maps). This application has links to a bewildering array of online map services and the ability to either automatically cache on the device, or manually download an area for offline use on the device.

For commercial maps (OS or IGN) I prefer the Viewranger app, because it allows purchase and download on a tile by tile basis, or through packages of map data for predefined areas. I also use the beacon functionality within Viewranger for sending my location to the excellent Social Hiking / ShareYourAdventure site.

A number of pre-built maps are available from in sqlite format, and you can use the application Mobile Atlas Creator to build your own custom maps from a number of sources.


In order to use a map on a Garmin handheld GPS you need to get the data into the Garmin img format - which you can simply drop onto a modern device via USB.  

By far and above the simplest way to get a Garmin img file is to grab an image (.img) file from one of the existing services for pre-packaged OSM data. I used to recommend a series of possibilities for maps - but these days the best source WW is the Open MTB (Mountain Bike Maps) service - the first image above. That said, the OpenTopoMap looks interesting

If you need routable maps for driving, try following these instructions to grab a selection of map tiles from this server in the Netherlands.

Alternative services do exist (TalkyToasterRaven Family and raumbezug) but they're generally not as up-to-date as the services above. If you’ve got an older device, you’ll need to use cgpsmapper and sendmap.  It is possible to take the map data, and get Garmin’s mapsource to read it, but it is a more involved process.  

Creating your own maps from the OSM data

If you don’t like the styles of the above maps, or want a really up to date map from current OSM data, there are a number of programs that will allow you to create your own maps from the data.  You can try the instructions below which have worked for me in the past, however there’s now a much better and more up to date guide on the openmtbmap page.

  • First grab the OSM data (typically .osm).  I’ve found 2 ways  to do this successfully               
    • For small areas, and the most up-to-date data - grab josm, register an openstreetmap account and enter your username in the settings; then download the data for the area you’re interested in, and save it to an OSM file.
    • For larger areas (whole countries), download the osm.bz2 file from cloudmade or geofabrik and extract it with something like 7zip
    • Then convert it to an img file for sending to your GPS (assuming you have a recent USB device that supports img files).  I’ve had the best luck using mkgmap, with a command line as below.  If you’re loading multiple maps onto your GPS, be sure to give your maps a unique mapname (8 digit number) - otherwise you’ll only be able to see one of them.               
      • java -Xmx1024m -jar mkgmap.jar —mapname=63241234 —code-page=1252 —tdbfile —gmapsupp —latin1 —generate-sea=multipolygon —country-abbr=MC1 —country-name=MOROCCO —road-name-pois —route —product-id=99 —family-id=99 —family-name=”OSM Maps” —description=”OSM Casa” casablanca.osm
      • I haven’t quite worked out how to get the —generate-sea command working at the moment. My last attempt for Lisbon seemed to have catastrophically flooded most of the city. You may find more job and less frustration by using the pre-packaged img files described above.


Of course if you’re using OpenStreetMap data - and find something that’s not on the map - then you’ll be keen to fix the map and make the correction!  There are several ways to contribute to OSM - the easiest being simply to upload the tracklogs from your gps unit. This is really easy, and allows anyone who is working on the map in that area to make updates. Just make sure that as you’re walking you have the GPS set to save your movements to a track. Once you get back to a PC - you’ll be able to grab the GPX file that represents that track and upload it to (after you’ve created yourself an account).

If you have an android smartphone, then you can capture additional data whilst you’re out with OSMTracker, and then use it later when editing via JOSM to make the changes, or make small updates (tags) live from your device using OSMapTuner.

There are 2 mainstream editing packages - which you can use to map the GPX file you captured on your GPS, and/or fill in details using satellite images from Bing (details of the Microsoft Bing OSM license). Potlatch2 - which is built into (under the edit tab screenshot), and probably the simplest place to start contributing.  JOSM - is a more powerful tool - although it does have a learning curve - so it is well worth doing one of the tutorial videos or looking for one on YouTube.





Other map data options

The 4UMapsrendering can be converted to a Garmin compatible kmz file using Mobile Atlas Creator, however these aren't usually as optimal as the vector img format.

In addition to data sourced from OSM, there are a number of other options.  GPS Map Search appears to offer open-source maps, including some with topo data, but I’ve not had much luck getting these to work.  I haven’t tested them - but mapstor seems to be offering a collection of topo maps created by the military agencies of Russia and some East European countries. In the US - GPS File Depot is apparently the best source for US topo maps, and has a limited selection of international maps (ref GPS TrackLog). In New Zealand - there’s an excellent resource at the NZ Open GPS project.  It isn’t OSM, but it is ready to roll for Garmin devices.