[mkgmap-dev] Tile names in IMG files

Fri Sep 4 13:21:37 BST 2009

Hi

On 04/09/09 10:16, Steve Hosgood wrote:
> "I<hex number>.GMP". Does anyone know how the<hex number>  is derived
> please? I guess that it is a bit-interleave of the latitude and
> longitude of some reference-point in the tile, but it could be a
> byte-interleave, or a nybble-interleave, or the interleave is done with
> the number expressed in decimal or whatever.

I don't think there is any big significance to the names, they
can be fairly arbitrary strings.

> I guess mkgmap must generate tiles too, so this info is likely
> well-known to those involved in the code.

We just use digit only names and the number is assigned by the
mapmaker, or the tool they use to split the map.

..Steve

> BTW: I gather that is possible for subtile files to be given
> decimal-based filenames too. How does that work? Is there any difference
> in the actual files depending on the naming system used?

Yes that is what mkgmap does.  I don't think it makes any
difference to anything else.