Yesterday’s post was about CloudMade, a website where you can download Garmin map files based on OpenStreetMap data for any country in the world that has OSM data. But all the map tiles for a country or state are combined into a single gmapsupp.img file, which means you can’t install the tiles into Garmin’s MapSource program. Because of this limitation, you can’t combine them with other mapsets and upload them to your Garmin GPS using MapSource. But there’s a simple way to break that gmapsupp.img file into the component subtiles, which can then be installed into MapSource, and uploaded with other mapsets.
First, download the program gmaptool, and unzip it into the directory of your choice; this used to be a command-line utility, but now comes in a handy GUI format that drives the command line tool gmt.exe. Next, start up the program, navigate to the directory that contains the gmapsupp.img, and open the file:
Click on the Split tab, select the directory you want to put the tiles in, and select “single maps” from the dropdown:
Click on the “Split all” button, and the subtiles contained with the gmapsupp.img file will be extracted, and listed in a status window:
You can now use a program like MapSet Toolkit to install the tiles for viewing in MapSource, and uploading individually or combined with other mapsets into your Garmin GPS:
Note: The dropdown on the “Split” tab includes the option for creating files for installing the tiles directly into MapSource, but it doesn’t seem to be working right now. Running the install.bat file gives an error message saying that the needed program cgpsmapper can’t be found, and specifying the path for this file under the Options tab doesn’t solve the problem. I suspect this will work at some point in the future.
The command line program gmt.exe driven by the GMapTool GUI contains many additional advanced functions for handling Garmin map files, not all of which are currently accessible using the GUI, including removing/changing unlock codes (no, this won’t let you pirate Garmin mapsets), making maps transparent, and more. Check the readme.txt file that comes with the program for more info; there’s also a “gmaptool_en.html” help file with more info on the GMapTool GUI.