Hi Gerd

Have been checking a few garmin tdbs and it appears that

while the first 3 bytes remain the same for each, ie 01 00 00,

the last four bytes are always different and never zero !

also ,except with mkgmap tiles, I have not come across C3 in the second byte ie a 01 c3 00 

Nick


On 05/02/2018 08:36, Gerd Petermann wrote:
Hi,

Ive discussed with Frank if there might be a field in the tdb file that has to be changed.
Maybe there is a value that tells MapSource something about the alignment of DEM data?

I don't have a single original Garmin tdb file :-(

It seems that mkgmap writes some constants that might be important, e.g. MapDetailBlock.java contains
//01 c3 00 ff
			os.write4(0xff00c301);
			os.write(0);
			os.write(0);
			os.write(0);

The wiki [1] describes these 7 bytes as 
"byte:0 has copyright text,byte 1: has 0x53 text : byte 2:if 1 then bytes 3_7: an unknown total (density) "

The display tool seems to expect something similar to the wiki:
			d.rawValue(2, "01 01");
			d.byteValue("intro flag");
			d.intValue("intro %d");

Any idea what this "intro" or "unknown total(density) could be ? 
And what is the 0x53 text?

[1]https://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin/TDB_File_Format

Gerd
_______________________________________________
mkgmap-dev mailing list
mkgmap-dev@lists.mkgmap.org.uk
http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev