how to combine Garmin map tiles?

Discussion in 'Mapping & Navigation' started by mpatch, Nov 2, 2013.

  1. mpatch

    mpatch Long timer

    Apr 10, 2011
    N Colorado
    I searched but the only info I found was pretty old. Trying to combine garmin 24k's small tiles into larger tiles so I dont exceed the 4000 tile limit.
  2. NorthernTraveler

    NorthernTraveler Long time Adventurer

    Jan 1, 2009
    The Big Mitten
    I used the old info to combine Topo V3 (takes lots of time, but works) and made it work US Road & Rec also.

    Couldn't get it to work on Topo 2008.

    Might not work for newer topo maps.

    Here are the old instructions -
    Instructions for using CombineMaps.exe on Garmin's US Topo maps to reduce the
    number of map segments.

    Step 1) Download tools & setup environment.
    Download the combinemaps tool from here:
    You will also need version 0085 or earlier of cgpsmapper. You can download 0085 from here:
    Download genPreview from here:
    Download gpsmapedit from here:

    Using winzip or other tool, extract to a folder. For these instructions
    I'm going to assume that you extract to a folder called "MapTools" on your C: drive.
    Unzip to the same folder.
    Move genPreview.exe to the same folder.
    Unzip gpsmapedit to "c:\MapTools\gpsmapedit"

    Now setup the path. For Windows XP, Start->Settings->Control Panel
    If not using the classic view, click on "Performance and Maintenace"
    Click on System, then click on the "Advanced" tab, then click on "Environment Variables"
    In the scroll box labled "System variables" look for "Path", select it, then click on "Edit"
    Go to the end of the variable value and enter ;"c:\MapTools";"c:\MapTools\GPSmap0085";"c:\MapTools\gpsmapedit"
    Then click on "OK", "OK", "OK"

    You will also need to have all the .img files from the US Topo maps on your harddrive.
    If you don't already have the US Topo maps on your harddrive see this post for instructions:
    Make sure that you edited the registry correctly by starting MapSource.

    Step 2) Run CombineMaps.exe
    First open up a command prompt window. Start->Run, then type cmd and click "OK".
    Test to make sure that the path was set correctly, from the command prompt type:
    and then hit enter. You should see a popup from cgpsmapper, check the third line to make sure it's 0085, then close the popup.
    If you don't see the popup then you need to edit your path again and check your spelling.
    Now run CombineMaps.exe, I'm assuming that you unzipped to "C:\MapTools" and that your current
    US Topo maps are in subdirectories in "C:\Garmin\Topo" , and that you want the combined maps to be put in "C:\Garmin\US Topo Big Segments".
    From the command prompt enter:
    combinemaps "C:\MapTools\USTopo.cfg" "C:\MapTools\USTopoGDBFiles" "C:\Garmin\Topo" "C:\Garmin\US Topo Big Segments"
    CombineMaps will then combine the 6639 segments of the US Topo maps into 370 larger segments.
    NOTE: The program will take a LONG time to run. On my computer (Athlon XP 3000+) it took a little over 36 hours.
    If you need to stop the program for some reason or the computer crashes then you can start Step 2) over
    and combinemaps will pick up where it left off.

    Step 3) Generate the files needed to use the new combined maps in MapSource.
    From the command prompt go to the directory for the new maps:
    cd \Garmin\US Topo Big Segments
    Run genPreview:
    genPreview -m"US Topo" -s.\IMG -f05,00
    "US Topo" will be the name of the new map and genPreview will create four files, you should have:
    US Topo Install.reg
    US Topo UnInstall.reg
    US Topo.tdb

    Now run cgpsmapper to generate the overview .img file from the .mp file.
    cgpsmapper "US"
    If you used a different name for the map for genPreview use the name you used followed by .mp
    Now from windows explorer double click on "US Topo Install.reg", click on yes when it asks if you are
    sure you want to add the information to the registry.
    Now start MapSource, you should now see the new US Topo maps. However, you won't see much other than
    a yellow screen with a bunch of grey rectangles. If you zoom in to an area you will see the detail from
    the topo maps.

    Step 4) Add features to the overview .img file.
    The overview .img file contains definition areas for the map segments (the grey rectangles) as well
    as map features that are shown when you zoom out far enough that the detail from the individual map
    segments aren't shown.
    Start gpsmapedit, from the command line:
    Now add the overview .img files from the original US Topo maps, File->Add, then select "Topo100USE.img" from
    the directory where the original US Topo East maps are installed. then click on open.
    Now add, File->Add, "Topo100USW.img", then add "Topo100Alaska.img", then add "Topo100Hawaii.img". You should
    now see the continental US, Alaska, and Hawaii on the screen.
    Delete the definition areas, Edit->Select->By Type..., then click the box next to 0x004a, then click on ok. then
    Now to fix a little problem, Tools->Edit Postal Address Items..., then click the Provinces/States/Regions tab, scroll
    down until you see "- - Bahamas", click on it and then click on Rename. put in Bahamas for the name and BAH for the
    abbreviated name, then click on ok. Then scroll down to "- - Russia" and give it the name Russia and RUS.
    Now save the map, File->Save As..., navigate to the "US Topo Big Segments" directory,
    change the "Save as Type" to "Polish Format" and the name to "" and click on "Save".
    Now close gpsmapedit.
    Make a backup copy of "US", from the command prompt:
    copy "US" "US"
    Start gpsmapedit again, and open "US", File->Open and select "US" then click "Open"
    Now add "", File->Add and select "" then click "Open", now save the result, File->Save Map
    Close gpsmapedit.
    Now "US" contains the new definition areas from "US" as well as the features from the original overview .img files.
    Now to get it in the .img format, from the command line:
    cgpsmapper "US"
    It will take longer to run this time since there is a lot more to convert.
    Once it's done, start MapSource and enjoy!!

    What combinemaps does:
    CombineMaps takes four parameters, the first is a config file, the second is the directory that contains the .gdb files to use,
    the third is the top level directory that contains the original .img files, and the fourth is the directory to put the
    new combined .img files.
    First it will read the config file, get a list of all the .gdb files, get a list of all the original .img files, and create
    the directory to put the results, then create an IMG directory and temp directory under the destination directory.
    Next it will read the first .gdb file. The .gdb file contains the map segments to combine into a single segment. The .gdb file
    is simply the file that is saved from MapSource after selected a set of maps. The filename for the .gdb file is in the format of
    mapID-mapName, where mapID is a unique 8 digit map id to be used for the combined map, and mapName is the name to use for the
    combined map.
    Then for each map segment in the .gdb file, it copies the associated .img file from the original dir to the temp dir
    Runs cgpsmapper to convert the .img file to an .mp file
    Note that versions of cgpsmapper later than version 0085 won't convert an .img file to an .mp file which is why 0085 or earlier is needed.
    Erases the .img file (cgpsmapper creates the .mp file in the same dir as the .img file and I wanted to keep the orignal dir clean)
    After all the .mp files are created they are combined to a single .mp file.
    The redundant [IMG-ID] headers are removed from the .mp file, the ID is changed to the mapID in the .gdb filename, the
    Name is changed to the mapName in the .gdb filename, and any other changes specified in the config file are made.
    Runs cgpsmapper to convert the combined .mp file to an .img file. This is the step that takes most of the time.
    The .img file is moved from the temp dir to the IMG dir.
    It reads the next .gdb file and repeats the process.

    If you don't like the way I've combined the segments, you can create your own groupings. Select the segments you want to combine
    in MapSource and then save the .gdb file using the naming convention described above. Note that cgpsmapper will create map segments
    larger than 8Meg, but they will cause MapSource to crash, so keep the groupings under 8Meg. Also the free version of cgpsmapper
    doesn't support irregular map bounadries so the selections need to be rectangular.

    The new map is a map "Family" instead of a "Product" so custom TYP files can be used with it.

    During the process changes specified in the config file are applied. The config file can be changed to delete features, change a
    feature from one type to another, etc. Some things that can be done is to make the final map transparent and remove all the roads.
    You can then use the map with a City Navigator map without the old or redundant roads in the topo maps. You could also create a TYP
    file for the City Navigator map to keep the inacurate lakes and rivers from displaying so that you see the more accurate ones from
    the topo maps.
    The topo maps also contain features such as boat ramps that can't be searched for in the gps, these features can be changed to a type
    that can be searched for.
    The config file is described in ConfigFileDoc.txt, if you don't know anything about .mp files, feature types etc. then you should also
    read the cgpsmapper manual (

    CombineMaps can be used with other maps other than the US Topo maps. You could use them with the new US Topo 2008 maps, the
    US Topo 24k National Parks maps, etc. You would just need to create the .gdb files to specify what segments to combine. Note, the DEM data
    in the US Topo 2008 maps and in the US Topo 24k maps would be lost as well as the routing info in the 24k National Parks maps.
    Losing the DEM data from the maps can be a good thing as it takes a lot of space and isn't that useful on the gps. You can still have
    the original map with the shading in MapSource as well as the new combined map. You would use the nice map with shading to plan your trip,
    and use the much smaller modified map in the gps.

    Test, test.
  3. mpatch

    mpatch Long timer

    Apr 10, 2011
    N Colorado
    So I would lose auto routing on my 24k topos?
    As of now I have all of the 24k's, CNNA, along with some bluecharts and osm on a 32GB card, it's not very convenient to change the .img extensions in accordance to what maps I want to show up. It wouldnt be so bad if I could change them from the GPS or if the tile limit was only for enabled maps.
  4. mcnut

    mcnut Long timer

    Apr 26, 2006
    Bakersfield CA & Sammamish WA
    I understand that it would be nice to have everything on 1 card but why not load by region? My 60 has a 2025 tile limit and I handle it on 2 cards and keep a small 3rd card for very area specific, say a vacation in FL.

    The trick to loading by region is to overlap the coverage a fair amount so that if near the edge of a coverage are you don't have to be continually swapping the card.

  5. mpatch

    mpatch Long timer

    Apr 10, 2011
    N Colorado
    For me its just ease of use. For a top of the line GPS the tile limit is a joke. I wouldnt think it would be too hard for garmin to either 86 the tile limit or offer revised maps for newer units with fewer larger tiles. Look at city nav, its only 175ish tiles and about 2GB of data yet 24k topo SW is about 3GB but has 1794 tiles.
  6. mcnut

    mcnut Long timer

    Apr 26, 2006
    Bakersfield CA & Sammamish WA
    Guess I'm just old school enough to still be impressed that I can load everything from the Pacific Coast to the foothills of the Rockies with CN, TOPO 100k & R&R along with LBMaps Baja. A 2nd card has the Rockies and west 1/2 way to the cost.
    Not planning to travel the plains anytime soon.

    I think Topo tiles are quads as opposed to the geopolitical boundaries of CN & R&R.

    Even Windows has a max file limit.

  7. NorthernTraveler

    NorthernTraveler Long time Adventurer

    Jan 1, 2009
    The Big Mitten
    Lots of the newer Garmin units have a tile limit around 4000 tiles.

    As was pointed out, the newer CN has bigger tiles.

    I'm told that Mapsource limits tile size to 8mb.

    The old Road & Rec had tiles sizes as small as a few 100 k's and over 3000 map segments. It was designed for the old GPS's with small memory sizes. My recompiled version of R&R has 95 segments of 4-7mb typically.

    The reason there is a tile limit is that there has to be a list of tile names and boundaries so the unit can figure out what map segment to look in for a given location. The longer that list the more memory it takes and the longer it takes to update the map display.