How to use OpenStreet maps in Garmin GPS

Garmin GPS (at least in Oregon and similar devices) can be enhanced by so called "Custom maps". Their usage, at least from my experiences, is limited to small maps (like park or campus plans). However, there are many open, large-scale maps around, notably in the OpenStreetMap project, that would be great to have in your GPS device (some of them are even routable, navigable). I was very pleased when a friend of mine told me that it was, indeed, possible.

The main site where are all the gory details is this: http://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin. Here is just a quick start how to do it:

• Find a map you are interested in and download it to your computer. A good place to start with is here: http://garmin.na1400.info/routable.php. The downloaded file has a file extension ".img" (e.g. 632490265.img). The mentioned site allows to download one tile as an ".img" file, or you can combine more tiles into one ".img" file (using the option "Build your map").
• On the SD card of your Garmin GPS, create a directory "Garmin" and copy there your downloaded ".img" file but rename it to "gmapsupp2.img" - if it is not the first file there, increase the number (e.g your files may be "gmapsupp2.img", "gmapsupp3.img",...).

That's is.

Once you have a map in your Garmin device, however, you may start looking for how to see the same map also on your PC in the Garmin's MapSource program. That would give you a better chance for planning and evaluating the trips. And, indeed, it is also possible. The detailed instructions are here: http://freegeographytools.com/2007/adding-garmin-img-files-to-mapsource. You have to install first two programs on your PC: MapSetToolkit and cGPSmapper, and than follow the instructions. Here is an example of a map from the West Australie (town Geraldton):