Instructions for downloading and using the maps


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Installing the Map on an SD Card

  1. Unzip the gmapsupp zip file that you downloaded. You will have a file called gmapsupp.img.
  2. Insert your SD Card into your SD Card reader. If you don't have an SD Card reader you can connect your Garmin GPS to your computer with a USB cable. Make sure that the SD Card is in the GPS unit before you plug it into the computer.
  3. Open the SD Card with the file manager. If there isn't a folder on the SD Card called Garmin, create one.
  4. Copy the gmapsupp.img file into the Garmin folder on the SD Card. The folder name must begin with a capital "G".
    The map will not work if you put the file in the Garmin folder of the GPS device itself. The map must be placed in the Garmin folder of the SD Card.
    On some device you'll need to use the folder name Map (with capital "M") instead of the Garmin folder. Create the folder on the SD Card if it does not already exist.
  5. Safely remove the SD Card once the file has finished copying.
  6. Turn on your Garmin GPS with the SD Card inserted and go through the following screens on your device:

    SettingsMap & VehiclemyMaps

    If you don't see "Map & Vehicle" in Settings, you likely have an older device, and you'll need to use these screen navigation steps:

    ToolsSettingsMapMap Info

    You should see the OpenMapChest map or maps in the list. Check the box beside the OpenMapChest maps to enable them. You should also uncheck the built-in map if the map areas overlap.

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Adding gmap to Windows BaseCamp

  1. Unzip the gmap file that you downloaded. You should have a folder named "OpenMapChest <map name>.gmap”.
  2. Move the .gmap folder to “C:\Program Files (x86)\Garmin\BaseCamp\Maps\”.
    The installation folder can be different on some computers. Try moving the .gmap folder to “C:\Garmin\Maps\” if the first folder doesn't work and this folder is present.

    An alternative on Windows 10 is to put the .gmap folder in “C:\ProgramData\GARMIN\Maps\”. This requires you to “unhide” the hidden ProgramData folder before the .gmap folder can be moved there.
  3. BaseCamp should be able to see the map the next time it starts. You should be able to enable the map from the “Maps” menu.
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Adding gmap to MacOS BaseCamp

  1. Unzip the gmap file that you downloaded. You should have a folder named “OpenMapChest <map name>.gmap”.
  2. Use Finder to locate your Application folder.
  3. Hold Ctrl and click on the BaseCamp app icon. Select “Show Package Contents”.
  4. The “Contents” folder should show up. Select it and you will find a lot of files and folders.
  5. Drag “OpenMapChest <map name>.gmap” into the “Resources” folder.
  6. BaseCamp should be able to see the map the next time it starts. You should be able to enable the map from the “Maps” menu.
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Testing the maps

It's possible to test a map when you're not in the area that the map covers. These instructions were made using a Garmin 255W but other devices will have a similar procedure.

  1. First, you need to put your GPS device into simulation mode. From the main screen, go through the following screen navigation:

    Tools Settings System

    From the system screen you can turn on the GPS Simulator.

    Simulator Off Simulator On
  2. Return to the main screen by pressing the back button a few times.
  3. Next you need to set the location to a point in the country that you want to test the map in. From the main screen, go through the following screen navigation:

    Where To? Favorites All Favorites Select any saved POI Map
  4. You will now be in the map view. You need to set a specific location in the target country.

    • Zoom out until you can noticeably see countries on the map.
    • Drag your finger across the screen and move the map towards the country you would like to test.
    • Zoom in again ensuring that the country that you want to test the map in remains in the center of the screen as you are zooming.
    • Put the cursor on a road and press the Set Loc button at the bottom of the screen
  5. Return to the main screen again by pressing the back button a few times.
  6. You can now test the map as if you were at the location that you have set previously. The GPS can even simulate the route to be driven for the POIs, addresses or other locations you want to navigate to.
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Using Two Maps at the Same Time

Some GPS devices with updated firmware from Garmin are able to load two maps at the same time. The first file should be named gmapsupp.img and the second file named gmapsup1.img. Both files need to be in the Garmin folder on the SD Card.

Newer Garmin devices (e.g. eTrex 20/30) can load multiple maps by placing the .img files directly in the Garmin folder. The only requirement is that the filenames end with .img.

Routing between multiple maps is currently not working. Driving across a map boundary requires you to navigate to a point near the edge a mapset and then continue with normal routing when you're over the map boundary.