[mkgmap-dev] Short Arc Problem? Error 3 Mapsource, Problem on Calculating this route Basecamp.

Thu Jan 3 19:56:55 GMT 2013

Yes it's confusing. So let's track it down.

Input:
way 114405617 [highway=tertiary; ref=GI-681]
way 81232137 [no tags]
relation 1596434 [area=yes; highway=residential; type=multipolygon]

Output of the mp algorithm:
way 114405617 [highway=tertiary; ref=GI-681]
way 81232137 [no tags]
way C114405617 [area=yes; highway=residential; mkgmap:mp_created=true; 
mkgmap:stylefilter=polyline]
way C81232137 [area=yes; highway=residential; mkgmap:mp_created=true; 
mkgmap:stylefilter=polyline]
way P1596434 [area=yes; highway=residential;  mkgmap:mp_created=true; 
mkgmap:stylefilter=polygon]

C114405617 is a copy of 114405617
P1596434 is the resulting polygon of the mp.

Is it now more clear?

WanMil

> But I still don't get it fully.
> Is the MP creating a new line, or adding the tags?
>
> Because now there would be two conflicting highway keys...
>
> I think it would be good to have a behaviour to only add keys to the
> underlying line, but not overwrite or not double if its a line...
> because I don't think I can add a check like:
> highway=* & highway=residential & mkgmap:mp_created=true {delete
> highway=residential}
>
> (without deleting both highway keys...).
>
>
> Are there any cases, where we really need highways from multipolygon in
> case highway already exists on the line itself?
> On 03.01.2013 20:17, WanMil wrote:
>> Maybe it helps if I explain what happens in detail with the mp:
>>
>> 1. The mp calculates the tags for the mp. In this case the tags of the
>> mp are used which are [area=yes; highway=residential]
>> 2. These mp tags are removed from all outer ways if they are
>> identical. In this case no tag is removed from way 114405617.
>> 3. All outer ways are copied and tagged with the mp tags. These copied
>> ways are only processed by the line style file. They can be identified
>> by the additional tag mkgmap:mp_created=true.
>> 4. All outer polygons are tagged with the mp tags and are processed by
>> the polygon style file only. They can also be identified by the
>> additional tag mkgmap:mp_created=true.
>>
>> Point 2 and 3 are required because in OSM the mp *and* the outer ways
>> are tagged quite often.
>>
>> In this case it creates a residential way (point 3) with identical
>> coords like the tertiary way 114405617.
>>
>> WanMil
>>
>>
>>> But that change causes problems for other parts. There are some
>>> highway=residential areas without ways that cross them, so in order to
>>> have routing work in some inner city cases, you must make sure that you
>>> route along the edges.
>>>
>>> If multipolygons were treated the same way as relations, that would make
>>> it easier to make sure only one routable highway gets created (because
>>> add highway onto highway would not add the highway, because there is
>>> already an underlying highway).
>>>
>>>
>>> The only thing I could think that does cause problems, if two routable
>>> lines are on top of each other, and both have the same road_type and
>>> same road_speed. Maybe there could be a check in the mkgmap continue
>>> function, never to create two routable lines on top of each other, if
>>> both road_speed and road_type are identical.
>>> On 03.01.2013 14:44, Minko wrote:
>>>>
>>>> The issue also disappears when you use
>>>> highway=residential & area!=yes [0x06 road_class=0 road_speed=2
>>>> resolution 22]
>>>> instead of the default rule
>>>> highway=residential [0x06 road_class=0 road_speed=2 resolution 22]
>>>>
>>>> So it got to do with those two routable lines on top of each other
>>>>
>>>>
>>>
>>
>