[mkgmap-dev] Problem with lakes and boundary lines

Thu Mar 16 13:08:18 GMT 2023

Hi Diego

If you get 'incomplete multipolygon relation' errors from the splitter,
for significant areas to be rendered, it is quite likely that you get
the effects you see. I don't know if the splitter makes any attempt to
complete the polygon along the edge of input area, but I suspect not as
trying to do this is a complex and error-prone process. So you end up
without a polygon.

Starting with an OSM extract that includes all significant polygons,
the splitter will, if keep-complete=true, pass on the complete polygon
to all tiles that include part of it. mkgmap can then do the necessary
multi-polygon processing and trim to the tile bounds.

Your osm data source probably trims everything to the exact regions, so
could include lots of incomplete polygons. Suggest you always start
with a larger area. Does splitter option -polygon-file give you the
results you expect?

Ticker

On Mon, 2023-03-13 at 10:04 +0000, helter skelter wrote:
> Hello guys 
> I have this problem when trying to render the map of separate regions
> of Italy, instead of the whole country. The problem is when there is
> a lake across the boundary line (it happens often in Italy).
> If I process the whole country, the lakes are rendered correctly,
> like in this picture:
>  
> (This is Lago Maggiore, between Piemonte and Lombardia regions, north
> of Italy) 
>  
> If I render each region separately, the lake is not rendered
> correctly. For example, rendering Lombardia I get this (picture from
> Basecamp) :
> 
> 
> The left part is not rendered because it’s another region (Piemonte)
> and this is ok.
> But also the lake is rendered completely wrong: only the south part
> has water (near Arona city) and in the north area the water is not
> rendered. 
> 
> If I create the map of Piemonte, I have the same problem but with
> different rendering errors. I see no water on the north and water
> covering a part of the land in center-right:
>  
>  
> Data of regions are downloaded
> from:http://download.openstreetmap.fr/extracts/europe/italy/ 
>  
> This is my SPLITTER configuration: 
> > Splitter version 653 compiled 2022-12-27T06:20:39+0000 
> > boundary-tags=use-exclude-list 
> > cache= 
> > description= 
> > geonames-file= 
> > handle-element-version=remove 
> > ignore-osm-bounds=false 
> > keep-complete=true 
> > mapid=13224200 
> > max-areas=2048 
> > max-nodes=1600000 
> > max-threads=16 (auto) 
> > mixed=false 
> > no-trim=false 
> > num-tiles= 
> > output=o5m 
> > output-dir=C:\OSM\splitter\PIEMONTE 
> > overlap=auto 
> > polygon-desc-file= 
> > polygon-file=C:\OSM\areas_poly\regioni\PIEMONTE.poly 
> > precomp-sea= 
> > problem-file= 
> > problem-report= 
> > resolution=13 
> > route-rel-values= 
> > search-limit=200000 
> > split-file= 
> > status-freq=120 
> > stop-after=dist 
> > wanted-admin-level=5 
> > write-kml= 
> > Elapsed time: 0s  Memory: Current 248MB (4MB used, 244MB free) Max
> > 16384MB 
> > Time started: Mon Mar 13 10:18:10 CET 2023 
> > Map is being split for resolution 13: 
> >  - area boundaries are aligned to 0x800 map units (0.0439453125
> > degrees) 
> >  - areas are multiples of 0x800 map units wide and high 
> 
>  
>  
> These are some errors I see in Splitter log: 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [225950136,
> > 123006579, 1073823032, 1073823028, 190504960, 87660763, 139898093,
> > 87660754, 87660747, 255065025, 255065026, 255065027, 202250553,
> > 202250554, 202252112, 256006208, 256006217, 256006211, 256006196,
> > 202273125, 87660744, 87660769, 265419850, 265419849, 196817044,
> > 202274997, 202274999, 202275000, 202274990, 202274996, 202274993,
> > 196817042, 263324120, 263327661, 263327665, 263324123, 265406984,
> > 265406978, 316366060, 269138792, 269138799, 87660748, 269138796,
> > 269138795, 87660742, 87660761, 198918369, 184747058, 184747048,
> > 87660750, 87660757, 187360834, 87660752, 87660746, 193114167,
> > 187361863, 87660743, 87660756, 87893267, 87893275, 87893277,
> > 814891333, 814891342, 814891332, 814891348] 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [339499330,
> > 339499338, 339499332, 339499337, 339499331] 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [173660449,
> > 203517579, 203517587, 173660454] 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [211154423,
> > 211154912, 366067218, 366067212, 366067214, 366067220, 366067216,
> > 366067222] 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [202421534,
> > 202421531] 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [202421542,
> > 202421532, 87896545] 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [222482940] 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [222484904,
> > 87896544, 87894927, 222496706, 222496701, 87894916, 87894926] 
> > Warning: Incomplete multipolygon relation 11758 (Lago Maggiore):
> > using bbox of unclosed polygon to calc tiles, ways: [87893287,
> > 186266917, 186266942, 87893262, 814465684] 
> >  
> 
> I took a look at OpenStreetMap but I really can’t understand if there
> is a problem with data and multipolygons. 
> Do you have any idea of how I could solve this problem ? 
> Thank you !
> Diego 
> 
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