Merging USA OSM Topo Routable Map Regions
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    19 years
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I have downloaded USA OSM Auto map regions and had no difficulty downloading or installing them on my Garmins. However, I never merged the regions to create a complete map of the USA.
I now want to download all 8 USA regions of the USA OSM Topo maps and install them. The process for the USA OSM Auto was pretty straight forward for me. I would move the .img file onto the Garmin and it worked.
The USA OSM Topo maps are a bit different. I have Windows 11 computers. I have the installation instructions, but it just isn't making sense to me. 7-Zip isn't a program that I typically use to extract files.
If anybody has any tips on how I can make this work, please feel free to pass them along. I sure wish the entire USA OSM Topo maps was available for download and I could simply extract it as a .img. It would make things so much simpler!
Is the purpose to have one
Is the purpose to have one complete map of lower 48 in Basecamp, not a Garmin, since one big map would be too big to fit within the 4GB SD (FAT32) filesize limit? The USA is the only country that won't fit in a single Garmin map, but it can fit in a single Basecamp map.
I have done this from a Mac.
I have done this from a Mac. But as AdvOSM has indicated the Map is too big to install on an SDCard. Works fine for BaseCamp. I followed these instructions at the URL below to merge the maps after downloading them and unzipping them with 7-Zip.
https://www.gmaptool.eu/en/content/merging-regions
Those instruction have you download an additional file "Base Map" named "OpenMapChest North America 2026.08.29 gmap.zip" and unzip it. Then you copy the Product1 sub directories from the 8 Regions to the Product1 directory of the Base Map. Then you use MapManager to install just the BaseMap. It pulls in all the regions.
Merging USA OSM Topo Routable Map Regions
No, my purpose is to eliminate the errors that I am seeing using JaVaWa Device Manager. The errors with the OSM Auto maps say:
"Segment codes from USAutoMidest.img exist in other files too."
(Mountain, Northeast, etc., say the same thing."
You make a great point, though, about Garmin file size limit of 4 GB. I was originally hoping to have the entire US on one map, but the size of the map is about 9 GB for USA OSM Topo, so that wouldn't work.
It looks like I either live with the errors or try to find another way to clear them up. In any case, I can't have the entire United States on one map for either USA OSM Auto or USA OSM Topo.
Converting GMAP to IMG
If you want to convert the GMAP installer to IMG files, you can do use GmapTool. I tried it as an experiment, and it worked. I will use the US Mountain map for an example.
Create a folder named, say, “Unpacked” on your hard disk.
Download and open the US_Mountain_OSM_Topo_v48.7z file in a file manager.
In that 7z file, open the folder US_Mountain_OSM_Topo.gmap
Unpack into the Unpacked folder all the individual files in the Product1 subfolder WITHOUT the lower subdirectory structure plus the three files with the extension typ. Yes, they need to be in one heap because Gmap tool is unable to recurse subdirectories. You will have over a thousand files with an eight-digit filename and three files with the typ extension.
Then use Gmaptool like this:
Click the Files tab
Click the Add Files button
Add all the files in the Unpacked folder
Click the Join tab
In the Output File box type in the complete path to your output file (with forward slashes, not backslashes), e.g. D:/Unpacked/US_Mountain_OSM_Topo.img
In the Mapset Name box type a name for the map, e.g. US Mountain OSM Topo
Click the Join All button. In one second you are done.
Move the output file into your Basecamp Garmin folder and check that it works.
So it is possible, it's just not easy.