[mkgmap-dev] cascading multipolygon relations

Mon Apr 13 15:47:19 BST 2009

2009/4/12 Martin Simon <grenzdebil at gmail.com>:
> 2009/4/12 Gleb Smirnoff <glebius at glebius.int.ru>:
>
>> Well, I've broke this cascaded relation into a simple one multipolygon
>> relation, and mkgmap still doesn't draw a lake in a middle of swamp.
>
> Hi!
>
> Have you tried zooming out or/and reducing detail on the device, in
> Mapsource or Qlandkarte?
>
> I observed that some (many) multipolygon holes only become visible
> when the low-detail version of the outer polygon is displayed...
>
> Example: this farmland near the stream "Logebach" I mapped last Weekend:
> http://informationfreeway.org/?lat=50.663655772998936&lon=7.287712349115571&zoom=15&layers=00000F0B0F

I had a second look at the multipolygons where this problem exists and
found out that if I zoom in (on the device) with the cursor right on
the edge of the multipolygon hole, I can select 2 "wood" polygons when
the hole disappears. So i suspect that in high zoom levels, mkgmap
cuts the holes correctly, but fills them with a polygon that has the
same object type as the outer polygon.
In my examples, this creates wood-in-wood polygons.

Even though I can't code, I hope this helps to fix the problem... :-)

-Martin