[mkgmap-dev] Wrong_route_calculation / strange straight routing lines on GPS

Thu Jan 29 16:14:56 GMT 2009

Carlos Dávila schrieb:
>> On Jan 28, 2009, at 23:10, Gert Münzel wrote:
>> /> making my first steps with mkgmap that, although the routing works  
> />/> fine in Mapsource, i get in trouble on my Gps unit Garmin gmap60csx.  
> />/> Very often i got these strange straight magenta routing lines in  
> />/> between normal routing.
> />/> Meanwhile i figured out that it seems to be that t has something to  
> />/> do with the length of a polyline. I don't know if it is the count of  
> />/> points/nodes of the polyline or still the lenght or both.
> />/> But comparing the same mp-file once compiled with mkgmap, once with  
> />/> cgpsmapper i see, that cgpsmapper split these long lines during  
> />/> mkgmap leave them like they are.
> />
>> How did you compare the IMG files? Have you tried decompiling the  
>> broken IMG with test.display.*? Have you tried manually splitting the  
>> polylines in the .mp-file? Does it help?
>>
>> My guess is that the problem lies with long polylines (in the .mp- 
>> file) that are split into several polylines (in the IMG) by mkgmap,  
>> which results in a road made up of several polylines.
>>
>> But if I understand you correctly, maybe the problem is just with long  
>> polylines in the IMG file?
> 
> 
> I think there must be something else than length of polylines and number 
> of nodes. I get this error in a route that always starts at a node in a 
> roundabout, no matter how far you fix the destination out of this point 
> or in how many pieces you split the way. In another case, error seems 
> to me to be related with the route crossing boundaries of an area 
> tagged as area=yes, landuse=industrial, place_name=Pol. Ind. Las 
> Capellanías
> 

Hi, Carlos,

actually i don't us roundabouts i my trailmap. I have a full routable 
version of this map created with cgpsmapper. The database is the same 
mp-file.
I guess not the count of pieces is important but there seems to be a max 
for length and/or cout of nodes.
Also i guess it's more a coincidence that you observe the problem 
starting with a roundabout.
I guess it's more like, if there are any polylines in any place of a 
calculated route, doesn't matter which type of polyline, which ar to 
long, you get in trouble with this route.

Regarding the tagging of areas, i'm sorry but yet i don't know anything 
about osm-format. I think if the the data is in correctmp-formam the 
results with mkgmap and cgpsmapper should be the same, and as i already 
mention my map compiled with cgpsmapper definitly works fine.
Also i use only a few small polygons for areas, which are not crossed by 
the route.
Ok, anyway maybe there are more then one reason for this problem.

cheers Gert