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[mkgmap-dev] mkgmap creates polygons that break Mapsource panning and also routing in some zoomlevels as well as crashing the GPS

From Mark Burton markb at ordern.com on Sun Sep 6 00:44:07 BST 2009

Hi Felix,
> thanks for your work,

You're welcome.

> by now I am sure (100%) which polygon was fucking up (as so far as being 
> the main cause). It's the forest here: 
> http://www.openstreetmap.org/?lat=47.70079&lon=16.18152&zoom=16&layers=B000FTF. 
> I have attached a screenshot of it' rendering in Mapsource.
> If you set detail level to lowest, decrease the mapsource window size 
> (e.g. to 240x240 pixels only), and then pan to it, you will notice that 
> you can still display it partly, but near to the center will crash.
> It was (I corrected it) connected at around 30 places to streets. On top 
> of it sometimes lines were parallel in order to draw holes into the 
> forest, so the intent here must have been to not show it at certain places.
> Even though this is bad tagging practice, mkgmap should not create maps 
> that send gps into rebot/crash, and also send mapsource 6.13.7 and 
> before into big problems.
> I am sure it was not the POI index overflowing, but has to do with nodes 
> shared between streets and polygon.

Lots of maps share nodes between roads and polygons and don't have
problems so there's more to this than just that.
> I have no clue why Mapsource suffocates on that forest if streets are 
> attached to it in osm database. Excluding rendering of the streets that 
> shared nodes with the forest would have the same effect as not rendering 
> the forest at all or skipping rendering another forest that was partly 
> overlaying at the same place.

Not sure what you're saying here. Did you mean that you could generate
a map that had either the forest or the streets but not both together?
> Well maybe you can still find out, Find in the new download:
> 1. Again the osm tile (I do hope my edits mean that tomorrow it will 
> render without problems (disconnected all streets and administrative 
> boarders, and corrected some of the nearly parallel lines).
> 2. not working with areas-pois
> 3. not working without without areas-pois
> 4. working excluding any rendering of wood=mixed & fixme=* and excluding 
> landuse=forest & fixme=*, with areas-pois
> 2-4 consisting of tile plus log.
> Get files for analysis (35MB) here: 
> http://openmtbmap.org/downloads/polygon_problem.zip

Thanks for putting that together. I am studying it but have nothing to
report at this time.

Is it easy to produce for me the osm file for just that forest region
(before your recent edits)? If so, please do that because I would like
to look at the osm data but the tile you sent me is too big for me to
load into josm. I guess I could use the splitter on that file to
extract the forest region.



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