Reducing extent of map


I’m making a specific map for the Pennine Way and have found contours and the osm data files i need. The problem is that the contour .img’s are for the whole of Great Britain + Ireland and when viewing the map in BaseCamp i get a lot more than i need.

Is there a way of telling mkgmap the bounds i want the finished gmapsupp.img to have? (The contours come as premade .img’s)

Thanks in advance for any help.

Did you try

You can split the contour data if they are in pbf format with osmconvert:

This data you can then merge with osm data with osmconvert like this:
osmconvert.exe map.osm.pbf contours.o5m -o=map_with_contours.o5m