Using GarminMapUpdater to perform Map Updates - Digital Elevation map image and Foursquare database issues - Caution
DEM Map issues
Several new Garmin On The Road devices offer a DEM or Digital Elevation Map with 3D Terrain which is a shaded relief map that overlays itself over the City Navigator map and provides a sense of hills and valleys. The devices that currently offer a DEM map are:
and for those with 3D Terrain, this Garmin faq applies:
To see if your GPS has a DEM map with 3D Terrain, go to the myMaps screen on the nuvi and look for something like: Cnna-Na-Dem North America DEM which should be checked. To see the map display without the DEM map, uncheck the DEM map in myMaps, then view the map on your GPS. As of March 2015, this map is offered on the nuvi 3590, 3597, 3598, and 3790.
In general, Garmin recommends that Garmin Express be used for map and other device updates. But several users continue to use an alternative, GarminMapUpdater, and at times Garmin also has recommended GarminMapUpdater for those users having difficulty updating their maps with Garmin Express. In fact, GarminMapUpdater is now the only means for doing map updates for folks updating with a Windows XP computer:
When performing a map update, this DEM map may be lost. If using Garmin Express to perform a map update, the DEM map is generally preserved but if using GarminMapUpdater software to update the map, this DEM map may disappear. If missing, GarminMapUpdater will have done one of two things:
1) it deleted the gmapdem.img file, or
2) it left the file but with a different name.
If the DEM map was eliminated, you'll need to replace it with the gmapdem.img file from the backup you hopefully saved from a previous map update. Or reinstall the City Navigator map update using Garmin Express.
If the DEM map was renamed, look for a file called something like DxxxxxxxB.img that is 608,976KB (623,591,424 bytes) and rename it gmapdem.img. (The file size is current as of March 2015 and earlier. Since the DEM map is not normally revised with a map update, this file size could be accurate for future map updates as well.) To be safe, write down the DxxxxxxxxB.img filename in case you need to rename it to its original filename. Even better, before tinkering with files on any device, make a full backup of the device's files to a hard disk or other storage method.
The DEM map, along with the other standard map update maps will be found in your 3597's .system folders. Look for the .img files.
If using a PC and you can't see the .system folder, you will need to change some settings on your PC's folder options and switch your GPS from MTP mode to MS mode:
Your GPS device will work just fine without the DEM map and honestly, the DEM map in my opinion is more a cosmetic feature than a necessary feature. Given that, I do really prefer seeing the DEM shaded relief when viewing the map so I don't want to see the DEM map lost on my devices.
There is one more possible issue if you've used GarminMapUpdater in the past on a GPS with the DEM map with 3D terrain. It is that in addition to the DEM map being present in your nuvi, you may also have a file (DxxxxxxxxB.img) with duplicate contents exactly the same filesize as the gmapdem.img file where the DxxxxxxxxB.img file is only taking up space on your device. If so, the DxxxxxxxxB.img file can be deleted—however, to be safe, first disable the DxxxxxxxxB.img file by renaming it DxxxxxxxxB.img.disabled, then see if your GPS continues to work and to display the shaded relief DEM map. If all is well, move the DxxxxxxxxB.img file from the nuvi to a computer backup to free space on your GPS.
Recent reports from a couple users state that in addition to GarminMapUpdater having issues with the gmapdem.img file, it also prevents updates to devices with gmap3d.img file (3D buildings) and this adds the nuvi 7x5 series to the list of devices that should not use GarminMapUpdater for map updates. Unlike the gmapdem.img file which is not locked and is not updated with map updates, the gm3d.img file is updated with each map update and is locked to the specific device. That means that while the gmapdem.img file can be restored from an older backup of a device's files, the gmap3d.img file with its unlock file tied to a specific City Navigator map version will be gone from a nuvi if GarminMapUpdater is used for map updates. Luckily, reinstalling the map update using Garmin Express will return the missing files.
Foursquare database file issue
Early reports on the new Garmin Drive devices indicate that the use of GarminMapUpdater on these devices will at least sometimes and maybe always not update the Foursquare database file but will delete the older file. See:
CraigW - Jul 2, 2017
Added warning for use with Drive models - thanks to t923347
CraigW - Aug 31, 2016
Added warnings for the nuvi 7x5 series and missing gmap3d files (3D buildings)
alandb - Apr 8, 2015
Updated faq per alandb's thread for folks using a Windows XP PC