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  1. #1
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    Reputation: veryavgwhtguy's Avatar
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    custom maps -- .img files onto Garmin

    I found a nice map that's downloadable for free. It's a swath of the US between certain longitudes, and is about 500mb. I'm trying to get it to display on a new Garmin eTrex 20.

    Half of the "instructions" for getting this onto a garmin just say to save the .img file in the Garmin folder on the device and it should work (mine doesn't). Then one site I looked at indicates you need to rename the file "gmapsupp.img". That doesn't help either.

    If I look at gpsfiledepot guidance, it says to download Mapset Toolkit, which furthermore uses cgpsmapper. So, I try to process the .img file using this method, and I get an error saying cgpsmapper tried to do something in an unusual way and the conversion failed.

    Looking for a little help here.

  2. #2
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    Reputation: NateHawk's Avatar
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    I don't know what you're reading. You need Garmin's Mapsource or Basecamp to load the map onto your GPS. I don't have either program installed on my office box so I can't remember what folder your mapset needs to go into for those programs to read it, but those instructions should be available on gpsfiledepot.

    That is assuming that the .img file contains vector data and is in Garmin's format. There's more than one type of .img file out there. One type contains raster imagery data and is an ERDAS Imagine filetype which is more common in professional circles. I use that type daily. You cannot load that type of .img file onto your GPS directly. Indirectly getting it on there would not be easy, either, because it would involve a number of file conversions. You have to wind up in .kmz to get raster data onto your GPS.

  3. #3
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    The first bit of advice was from Open Street Map Wiki. Crowdsourcing information is great until it isn't.

    The second was from gpsfiledepot, and it was a precursor to using basecamp or mapsource to load the maps.

    I found another source that claims to provide an executable that loads the map on my computer for use by basecamp or mapsource, similar to the way gpsfiledepot maps do. We'll see how that goes.

  4. #4
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    Quote Originally Posted by veryavgwhtguy View Post
    The first bit of advice was from Open Street Map Wiki. Crowdsourcing information is great until it isn't.

    The second was from gpsfiledepot, and it was a precursor to using basecamp or mapsource to load the maps.

    I found another source that claims to provide an executable that loads the map on my computer for use by basecamp or mapsource, similar to the way gpsfiledepot maps do. We'll see how that goes.
    I typically use the executable self installers that put maps where I need them (from GPSFileDepot. I have used GPX2IMG a couple of times to make my own transparent overlays of trail networks, but not enough to remember offhand where the .img files need to go.

    I have heard that renaming the file and replacing the gmapsupp.img file on the device should work. But I've never tried that method. I was more confused by the method to process the file with Mapset Toolkit. If you already have the .img file, I don't know why you'd need to process it further.

    hope the executable you found works out.

  5. #5
    sheep in FOX clothing
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    I vaguely recall successfully using this method back in the day.

    Renaming the map file didn't work, there was another little freeware program that let you compile a user-selected series of maps into the gmapsupp.img, but I totally forget what it was called.

    I'll try to find it on my PC and report back.

  6. #6
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    I got it to work using the OSM mapping provided by a third party. I have topo of my state already on the GPS as gmapsupp.img, which I wanted to retain. (Basecamp overwrites whatever you installed in the past with whatever you are trying to install now.) So, I just copied the new .img file to the Garmin folder on the device and renamed it to an 8 character file name. It worked, and now I have the old state topo and the new topo to choose from on the device.

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