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[mkgmap-dev] problems at map intersections?

From Valentijn Sessink valentyn at blub.net on Wed Jul 15 16:21:33 BST 2009

Hello list,

When trying to use a built map, I'm getting a bit odd results around the
edges of tiles - at least, I think it's the edges. It's not exactly on
the boundaries, but about 2.5 kilometers below the grey lines that show
up in Mapsource (I assume these are the tiles). But strangely, the
Splitter arealist has other numbers than Mapsource tells me.

You can see tiny interconnections where the roads meet on the tiles; on
the highest zoom levels, parts of the map start to dissapear.

For example:
wget 'http://download.geofabrik.de/osm/europe/netherlands.osm.bz2'
bzcat netherlands.osm.bz2 > netherlands.osm

Then use Splitter:
java -Xmx1700m -jar ./splitter.jar --max-nodes=500000 --overlap=8000

It produced the following list of areas (you may want to test with this
list instead of the automated --max-nodes)
63240001: 2363392,153600 to 2412544,239616
63240002: 2412544,153600 to 2428928,212992
63240003: 2412544,212992 to 2428928,239616
63240004: 2363392,239616 to 2402304,268288
63240005: 2363392,268288 to 2402304,337920
63240006: 2402304,239616 to 2428928,266240
63240007: 2402304,266240 to 2428928,337920
63240008: 2428928,153600 to 2443264,231424
63240009: 2428928,231424 to 2443264,262144
63240010: 2443264,153600 to 2500608,262144
63240011: 2428928,262144 to 2459648,296960
63240012: 2428928,296960 to 2459648,337920
63240013: 2459648,262144 to 2500608,294912
63240014: 2459648,294912 to 2500608,337920

(Splitter says, for example, that it splits 2428928,153600 to
2443264,231424, which would be 52.119141,3.295898 to 52.426758,4.965820,
but Mapsource shows a grey line around 52.07145)

Anyway: when you load the resulting map into Mapsource and go to
52.07149/5.02083 (or 52.07149/anywhere ), you'll notice small
interconnection traces on the more important roads (N230 and A2 in this
example), but from zoom level 50 meters and higher, parts of the map
will disappear. And if you experiment a bit, you'll notice that the map
will vanish at even lower zoom levels. For example - see attached lower
part of Mapsource.

java -enableassertions -Xmx1700m -jar mkgmap-r1087/mkgmap.jar
--country-name=Nederland --country-abbr=NL --latin1 --remove-short-arcs
--lower-case --preserve-element-order --location-autofill-1 --tdbfile -c

(I removed the routing information that I usually include, just to make
sure it's not a routing issue) (And as you can see, I learned from my
mistakes and used -enableassertions for map making).

The 52.07149 is an example, the same thing happens around 52.25606
(another 2.5 kilometers below a tile).

You can see the problem best at locations that are busy with roads and
stuff; also, having a main road (a thick one) nearby helps. I was
wondering if it has anything to do with areas that are cut of at the
edge, but that's pure guessing.

My Gærmïn Nüvï also has problems with these sites, refusing to route
and/or not showing the map at the lowest zoom levels.

If I can do anything to test, please say so.

Best regards,

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