Make the maps on the SD card visible in Basecamp
So now we've installed the maps to Basecamp on the Mac, and also installed them to an SD card to be read by the device. What we now want to do is be able to connect the Garmin device to the MacBook Air used for trips and for Basecamp to be able to read the maps, so we don't have to install the maps to the Macbook Air.
The maps have a software switch which makes them "visible in BaseCamp" or "not visible in BaseCamp". When the maps were transferred to the card this switch is set to "not visible in BaseCamp", so connecting the SD card reader to the Mac and firing up BC results in the following:
BC sees the card, but doesn't see any maps. The card is under devices, called SD1. Now, there is a complex way to set the "visible" switch to "on" by modifying the map file, or there's an easy way using JaVaWa Device Manager. As mentioned, JDM only runs in Windows.
Assuming you have access to a Windows machine, follow these steps.
3) Make the maps on the SD card visible in BC.
If you are using Windows in a virtual Machine on the Mac, first off close BC in the Mac, eject the SD card, and empty trash. Fire up Windows and connect the card. Make sure the card appears in File Explorer. Then run JDM. JDM will search removable drives and find any which have maps on them. In this case the removable device is my Montana, and the card has been desgnated drive G by Windows.
Click the manage maps button for G, or whatever it's designated on your PC.
You can do other stuff here, like change the name of the mapset, but all we'll do is click the button in the tool bar marked "visible in BC"
The little world icon in the map line indicates it's now visible in BC
If you have BC in Windows, you can see that the OSM maps are now readable from the card
In Windows, close down JDM, BC and eject the card. If you're using a VM, lose Windows and the VM.
Reconnect the card to the Mac, and fire up BC.
And now the OSM maps on the card are visible in BC for both Mac and Windows. BC will read the maps from a card reader, or if the card is inserted into the device. If you want to install the maps to your actual device, rather than have them on a card, just copy the OSM_maroc.img file to the Garmin folder on the device.
Disclaimer.
I've used a Garmin Montana here. There may be some complications with a Zumo devices, including that the folders where the maps are installed are hidden, and Zumo's don't read some types of map, notably raster maps like GB Discoverer. These OSM maps are vector though and will work with Zumo.