Thread: How to merge Garmin maps with Gmaptool

Originally Posted by yorkim

Thanks, there must be some other reason why it doesn’t work then. I am trying to join some of the new GB Ordnance Survey maps:
[Only registered and activated users can see links. ]
GMapTool creates an .img file, but Basecamp doesn’t read it and I get the following warning multiple times:
== Warning: repeated map ID number.
I wonder whether that is because the maps overlap. Does anyone know how I can join these files?

Yes you have overlapping tiles, there are some tiles with the same MapId.
Resulting .img, even if you remove overlapping tiles, would exceed 4 Gb, so not possible to use in GPS and to be displayed from SD in Basecamp.