I understand I can download the SRTS contours only as a map.
I also understand I can download the OpenTopoMap.
I also understand that I can use GMapTool in order to combine maps.
My specific questions would be (I guess):
Is there anywhere a description of how to use GMapTool on an unpacked OpenTopoMap and an unpacked SRTM map so that I receive a combined map - and how I can install that into BaseCamp and my Oregon 450?
Thanks a lot in advance (I hope I picked the correct forum - not sure if I should have posted this directly into the Garmin forum…?)
My Oregon 450 no longer works but I think it supported multiple gmapsupp.img. The garmin package for cyprus from opentopomaps contains two *.img files, so I don’t understand the problem. If you copy both into the garmin folder the device should show two different maps for cyprus and you should be able to enable both.
You can merge multiple individual gmapsupp files into a single file which will display as layers or maps on the Garmin device. It’s a command line option for mkgmap. I used to use it regularly for older etrex devices.
The downloaded zip files contain one .img map each. Unzip and copy both to the Garmin directory of your GPS device (or SD card).
If both are selected in the GPS menu, the contours should be visible as an overlay on the GPS device.
The two .img files can be combines into one Basecamp map using JaVaWa OSM combiner https://www.javawa.nl/osmcombiner_en.html
This creates a 3D map in Basecamp, which may be shown in 3D (Ctrl3), and you can also set a track or route to the map elevation.