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Breaking Up A Garmin gmapsupp.img Map File Into Separate Map Tiles

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:

gmaptool GUI

Click on the Split tab, select the directory you want to put the tiles in, and select “single maps” from the dropdown:

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Click on the “Split all” button, and the subtiles contained with the gmapsupp.img file will be extracted, and listed in a status window:

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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:

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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.

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8 Responses to “Breaking Up A Garmin gmapsupp.img Map File Into Separate Map Tiles”

  1. 1 Paul Cone

    Actually, you CAN combine multiple gmapsupp.img files into one file, using Mkgmap. This way you don’t have to use MapSource (which is not available on the Mac). There’s info here…

  2. 2 Clark

    Is there a Linux version of this program?

  3. 3 Leszek Pawlowicz

    GMapTool is a GUI for gmt.exe, a command-line program. So if you can’t get GMapTool to run in WINE, you should be able to gmt to work; see the readme.txt in the download file for command options.

  4. 4 Tony Grimley

    Leszek – I have downloaded GmapToolSetup047a.exe but, on trying to run it, Kaspersky has a message ‘riskware not-a-virus: RiskTool.win32.patcher.ab’ and deletes the program.
    Are you aware of this problem – if so, how can I get your ptogram to work/
    Many thanks

    Tony Grimley UK

  5. 5 Leszek Pawlowicz

    Haven’t heard of this problem before. Downloaded the latest version and scanned it with my antivirus (Avast), and it found nothing. I suspect it’s a false positive – I’ve seen that occasionally with other programs I know to be safe. Antivirus programs have algorithms that look for program patterns outside their virus definitions; that way, they can find viruses that might have been slightly modified, and aren’t in their definition lists yet. Sometimes, though, they’ll see a suspicious pattern in an innocuous program, but flag it anyway.

    You might try having someone else on a different computer download the program and scan it; if it looks OK, try copying it onto your system and see if you can get it by Kaspersky

  6. 6 James Blond

    Is there a virus-free version somewhere?

  7. 7 Leszek Pawlowicz

    I’ve scanned the program with Avast and Microsoft SE, and both have found no virus. I suspect it’s a false positive, but can’t be 100% sure.

  8. 8 Adi

    Avira AntiVir just tagged as a positive for SPR/Tool.Patcher.T.

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