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[mkgmap-dev] Size Limits

From Steve Ratcliffe steve at parabola.demon.co.uk on Thu Dec 11 00:05:58 GMT 2008


> I understand how to solve this problem (osmosis, osmcut, etc.) but I'm  
> wondering what the size limit is and whether it is imposed by the IMG  
> file format or mkgmap. Does anyone know?

The limit is in the IMG format, or at least the version of the format that
we know how to use.  It is not the size of the file as a whole but of one
section within it.  Files containing routing information for example will be much
bigger in total size.

The default style is somewhat heavyweight as it contains all residential
roads on two different zoom levels.  You would get about twice the amount
with a less heavy style.  (You could try --levels='0:23,1:21,2:19' for a
rough idea).

All garmin maps commercial or otherwise are split into tiles.
In the days before cheap SD cards it would have been a necessary feature
that the map was split into small enough chunks that you could load a few
sections you were interested in onto limited memory.


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