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

Wed Oct 20 15:47:15 BST 2010

El 19/10/10 22:06, Steve Ratcliffe escribió:
> On 19/10/10 15:58, Carlos Dávila wrote:
>    
>> Yesterday I tested pbf input for mkgmap for the first time. Map was
>> built apparently without errors, but using the resulting map on
>> MapSource I get a suboptimal route, compared with the one I get using
>> osm as input. I used portugal.osm and portugal.osm.pbf from geofabrik
>> for the test. Today geofabrik is offering corrupt excerpts, so I can't
>> make further tests by now.
>>      
> That is interesting.
>
> If the .osm and .osm.pbf contain the same data then mkgmap should
> produce exactly the same map in both cases ignoring timestamps
> if you add --preserve-element-order in both cases.
> In the cases I tested this was true.
>
> If it doesn't then it is a bug.
>
> Now the fact that if you don't have --preserve-element-order there
> could be differences in the order of the elements within the maps
> and I suppose that it could affect the routing.  If so that would be
> very interesting and might lead to improvements in routing in general.
I have repeated the test with today's portugal osm and pbf files from 
geofabrik and these are the results:
-Calculated routes are the same with or without --preserve-element-order 
for each osm pair and pbf pair.
-2 of 3 tested routes are worse with the pbf generated map.
-pbf generated map is slightly smaller than osm one (11.3 vs 11.4 MB), 
so it seems that some information may be missing in the pbf map.