Merging 2 img-maps together

I am a newbe and i have tried to merge 2 img files together with this command:

mkgmap --gmapsupp gmaps_NL.img gmaps_BE.img

The result was a file (gmapsupp.img) no bigger then 464 kB, which cann’t be read by my Etrex Vista.
I expected a file as big as 535 MB since that is the combined size of the original files.

What am i doing wrong?

On iMac I need to run java to run mkgmap so put
Java -jar in front of the rest of the mkgmap command.
In my case i need to use the path to java and mkgmap too.
/Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java -jar /Applications/mkgmap-r3132/mkgmap.jar --gmapsupp , etc --output-dir=/Users/xxx/Documents/xxx/

GMapTool is another tool to join img files

If you find all is not as expected it may be easiest to enable manual tile selection at this site and select all the area in one extract instead
or this Benelux area might suit you too (cycle suited, not for car routing)
or use this site where you can also select the whole area at once

Thank you for the info! I’m going for the that is the easiest option.

You can also try to combine two img’s with OSM combiner, a Javawa tool (based on mkgmap) that will merge the img tiles without having to know the ins and outs of mkgmap.

You might get problems if both img comes form the same map. This could mean that some parts have the same name - typ file or index file. Combining could remove duplicate parts, reducing some functionality.

If gmaps_NL.img and gmaps_BE.img come from (and are from the same date!) then there will be no issues with OSM combiner (it was made for this purpose).

It doesn’t work for me. Combining 2 img removes search index form second img.

I have my own map created with mkgmap. In Mapsource I select 2 sets of tiles and generate 2 img, then I combine both with mkgmap. Size of output img is different depending on order of input img, because removed indexes are different size.

I’m not sure if this error is enough to explain size difference that OP has observed (even assuming that all sizes are in MB).

The indexes (and routing facilities) are recreated by mkgmap by using the switches --index, --net and --route

I have tested mkgmap with options provided by OP. If you add --index, then shouldn’t you add --code-page too?

Edit: adding options --index doesn’t change mkgmap behavior. You would have to split img into tiles and then merge them back, to get new index. And in this case you should provide FID too. Code page is detected correctly.

OSM Combiner works best with the files, because they contain the necessary files for creating the overview map, but it can also use gmapsupp.img files. In the latter case it uses your GmapTool to split the files.
When creating the combined map with mkgmap it sets the following options:
area-name, draw-priority, latin1, code-page, show-profiles, net, route, product-id, index, tdbfile, family-name, family-id, series-name, description and overview-mapname