Greenland map problem

Hi,

I am trying build map of Greenland. I downloaded planet.osm because there is no extract for this country on geofabrik.de
There is not too much data so it shouldn’t be problem build this huge map.
But when I build a map I have only upper right corner of map and Iceland area (which also belong to this huge area).

Any idea what can be wrong? I am doing my extract this way:

osmosis --read-pbf file=“planet-121003.osm.pbf” --bounding-box top=84.00 left=-74.00 bottom=58.00 right=-10.00 --write-pbf omitmetadata=true greenland.osm.pbf

I also tried donwnload same area from http://garmin.openstreetmap.nl/ to check if there is some general problem, but this was fine.

Thanks for help

mira

Hi,

The problem was in splitter … --max-nodes=1600000 changed to --max-nodes=900000 solved problem
When I split with --max-nodes=1600000 then some “partial” img files had 0kB size when I builded map.
Interesting is that --max-nodes=1600000 was my usual setting before and I didn’t got this problem.

regards

mira

Hmm…
I still have “empty” south/west corner of my map.
There is not area in which I am interested, but anyway I am very curious what is wrong with my work-flow.

$ osmosis --read-pbf file=“planet-121003.osm.pbf” --bounding-box top=84.00 left=-74.00 bottom=58.00 right=-10.00 --write-pbf omitmetadata=true greenland.osm.pbf

$ java -Xmx3072m -jar splitter-r200/splitter.jar --max-nodes=900000 --no-trim --description=Greenland --mapid=63240001 --overlap=10000 --output=pbf --output-dir=LAND greenland.osm.pbf

$ java -ea -Xmx6144m -jar mkgmap-r2337/mkgmap.jar test18.TYP --precomp-sea=/media/MEGA/MAPING/sea/ --style-file=my-style/ -c my-style/arguments LAND/6324*.osm.pbf

Splitter yielding six files … 63240001-6.osm.pbf each having non-zero size, but when I am running mkgmap 6-th img file having size 0 bytes.

When I check my map in qlandkartegt it looks like it is created by 5 tiles.

Any idea what is wrong?

mira

My experience is that --overlap=10000 can lead to some problems, maybe try to lower this value (5000?)

I finally get time to try again … The problem was in splitter but in “max-nodes” value.
I didn’t noticed message after build of map:

There is not enough room in a single garmin map for all the input data
The .osm file should be split into smaller pieces first.

Usually map wasn’t build with this kind of error before so I didn’t expect this kind of problem.
Maybe something changed in mkgmap

I lowered value in “max-nodes” from 900000 to 700000 to solve this. Hmmm I used even 1600000 value before without problem

thank you

mira

Hi,

Next ugly issue with Greenland map I have is with huge glacier polygon.
Greenland is covered by huge glacier (cca 90%), but I can see just more or less eastern half of it.
I was trying different value for splitter “overlap” and fixed max-nodes=700000 … values between 6000 and 10000 for “overlap” will give me same result of seeing eastern half of glacier with other values I don’t see this glacier at all.

I know that splitter have problem with big polygons, but anyway maybe this “glacier issue” can fixed somehow?
http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2012q3/015031.html

Any workaround?

regards

mira

Hi,

I got a great improvement of this issue with this patch:
http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2012q4/015152.html

With this line in my problem_polygons.txt
rel:1279614 # Greenland glacier

Results varies on splitter values max-nodes and overlap
To get best result i run: --max-nodes=30000 --overlap=5000

I usually tried splitted tiles as big as possible e.g. --max-nodes=1000000 … Is there any disadvantage to have a lot of small tiles?

regards

mira

I don’t think there’s any disadvantage to small tiles, though there may be an upper limit to how many a GPS unit can handle

I don’t know, I guess the smaller the tiles, the more you have to deal with large multipolygons that are larger than the tiles and will be broken? :confused:

This sounds logical, but for unknown reason if I keep tiles bigger I still missing southern tip of Greenland glacier.
Maybe some havoc in osm data or I have to add some more relations to my problem_polygons.txt … I have to investigate this more. :frowning:

mira

What is usual limit? I have Garmin 78.

Thank you.

mira

I got this issue fixed by newest “splitter_problem_list_v2.patch”

http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2012q4/015195.html

So I now staying with bigger tiles happily :smiley: “–max-nodes=700000”

mira