[mkgmap-dev] Different routing results using osm vs osm.pbf

Tue Oct 19 23:13:37 BST 2010

Hi Scott

> The results should be identical comparing OSM versus PBF with or without
> that flag. Converting from osm to pbf with the default flags should
> preserve everything in the origional OSM file, including precision of
> coordinates, element order, metadata, tags, timestamps, etc. (The format
> offers some options that produce smaller filesizes at the cost of not
> preserving everything, but those are not on by default.). If there are
> any differences between maps with and without --preserve-element-order,
> that is something related to mkgmap, not PBF.

Yes, preserve-element-order is a mkgmap option.

With the option a linked hash map is used, so that the order of the
elements in the output is identical to that of the input.
Without the option the order of the elements in the output is
determined by the iteration order of a hash map and thus may depend on
the implementation differences between the pbf and osm readers.

But now you mention it I can't think of why there should be a
difference, since all the code that matters is common between the two.
I'll take a look.

..Steve