[mkgmap-dev] gmapsupp visible in Basecamp

Fri Oct 21 17:50:52 BST 2011

Just found out that you can make a gmapsupp.img on micro SD card or in your GPS unit visible in Basecamp. This becomes the common procedure by map sellers, they only deliver a gmapsupp on microSD card so you don't have to install the map on the pc anymore.

By default the Ms (Mapsource) flag is set to 1 but you can set it to 0 with Gmaptool:

Reading file G:/garmin/gmapsupp.img.

File:		G:/garmin/gmapsupp.img, length 46495744
Header:   	21.10.2011 18:36:39, DSKIMG, XOR 00, V 0.00, Ms 1

Set version in header - advanced option, GMapTool writes map version into img file header. First two input fields are for map version, field Ms is for Mapsource flag. Value 0 for flag makes img in GPS visible to BaseCamp.

I have tried it with my Openfietsmap and it worked. However I discovered that my map is transparent. Underneath it appeared the Basecamp basemap, a very rough map with highways that used my custom typ file (with the wrong lines of course). Any ideas how to make this basemap invisible? I think it has something to do with not using the 0x4b background; I dont use it because this causes ghost shading in Mapsource (zooming in produces a lot of noise, like this example: http://dl.dropbox.com/u/8541959/mapsource%20lines.jpg). If I edit my map with gpsmapedit, I can see this background polygon 4b is still there, but I simply dont have defined it in the typ file because of those unwanted effects in Mapsource.