[mkgmap-dev] MapSource crash with DEM: Maybe tdb file needs changes?

Mon Feb 5 11:16:53 GMT 2018

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
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