[mkgmap-dev] routing seems to depend on order of ways

Mon Dec 30 11:18:36 GMT 2013

Hi all,

really confusing...
The strange bug disappears in MapSource (6.16.3) when I (re-)activate option
"Try to avoid.."
"U-turns"

In Basecamp (4.25) , the bug appears as well when I deactivate "Feature type
avoidance"
"U-Turns".

Regarding the order of the ways in the OSM file:
It seems that the only important way is w3. If that appears as first way,
routing
is crazy. 
I think the reason is the order of the calculated routing nodes that
changes.
Because of the gate the the way w4 is spit into 3 parts, and the calculated
route seems to depend on
the order of the routing nodes related to way w4. If w3 comes first, the
node that connects 
it with w4 also comes first, else it comes later. 

I have no idea how to find the "right" order in a network. 
In NOD3, we sort the nodes "lexicographically by longitude, then latitude".
Maybe we should do the same for NOD1?

Gerd

WanMil wrote
> Hi,
> 
> I have commited the new (undocumented) option --x-no-mergeroads to 
> disable merging of roads. I think this is useful for chasing problems.
> 
> WanMil
> 
>> Hi Steve,
>>
>> I think I found a very old bug in mkgmap, it seems to exist since at
>> least r2210.
>> I found it while testing a patch for r2914 and found it in all older
>> versions that I tried.
>>
>> Attached are two test files and a gdb for MapSource.
>> The command that I use:
>> java -jar d:\mkgmap\dist\mkgmap_r2889.jar --link-pois-to-ways --route
>> --nsis --tdbfile --preserve-element-order  f:\osm\good.osm
>> or
>> java -jar d:\mkgmap\dist\mkgmap_r2889.jar --link-pois-to-ways --route
>> --nsis --tdbfile --preserve-element-order  f:\osm\bad.osm
>>
>> The only difference in the two files is the order of the ways w3 and w4
>> (the ids don't seem to matter)
>>
>> I use r2889 to test this because current trunk version uses a sort in
>> the RoadMerger, but the error is not related to the merge.
>> With bad.osm MapSource calculates a route that that passes the target
>> point, goes up to the barrier and then reverses back to the target.
>> This happens with vehicles like car and bike and seems not to be related
>> to any routing preferences.
>>
>> I hope you can reproduce the problem and find out what goes wrong...
>>
>> Gerd
>>
>>
>> _______________________________________________
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>> 

> mkgmap-dev at .org

>> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
>>
> 
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