[mkgmap-dev] Tile boundary artefacts

Mon Apr 5 18:35:17 BST 2010

I started to make very basic checks to get the source of the tile bounds 
problems.

I created the attached bbox1.osm and bbox2.osm. Both contain one 
rectangular polygon identical to the bounds. After compiling it with the 
default style I see in MapSource that the underlying land polygon 
(yellow) does not match to the data (blue) (see land_diff.png).

Any ideas why this happens? Do you have any hints how I could proceed 
and where I should continue my investigations?
Up to now I tried to decompile the img file with the Display project but 
failed on the RGN files (will need some time to investigate this).

WanMil

>> I have attached an interesting screenshot from my Oregon 400t. The map
>> is the All in one map Europe
>> (http://wiki.openstreetmap.org/wiki/All_in_one_Garmin_Map).
>>
>> You see that the light grey industrial area is splitted by a
>> considerable yellow line. But the dark grey buildings do not have it
>> although they are splitted by the tile bounds in the same manner. There
>> is no multipolygon defined in the screenshots area.
>>
>> Maybe the boundary clipper sometimes cuts too much?
>>
>> I have never seen such artefacts on original garmin maps.
>>
>> WanMil
>>
>
> I have checked the results of the AreaClipper and issued a warning in
> case one of the clipped polygons was not touching the clipped area. I
> found some but all of them were self intersecting polygons that were cut
> by the java Area class used by the AreaClipper.
>
> So that's not the source of the problem. Any other idea?
>
> WanMil
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