[mkgmap-dev] Finland with almost-working generate-sea

Tue Mar 9 20:35:00 GMT 2010

On Mar 9, 2010, at 20:20, Marko Mäkelä wrote:

>> I regularly take the entire Geofabrik extract of Europe and extract a
>> bounding-box containing all of Germany.
> 
> Have you been able to make it utilize all cores? I have a dual-core computer,
> and java is eating only one CPU.  Apparently, the bzip2 is already done.

No, but it seemed to me that the major bottleneck in my system was disk access, not CPU. However, I'm doing this on a laptop with a slow 5200rpm drive. I also normally decompress the .osm.bz2 files in  advance, as I often access them several times.

> [...]
> 
> According to http://wiki.openstreetmap.org/wiki/Osmosis/Detailed_Usage
> disabling the date parsing should not make a big difference.  I agree;
> both --merge and extracting natural=coastline have been relatively fast.

I have been using Osmosis 0.31.1. At least with this version, disabling date parsing made a huge difference. It could be that more recent releases are more efficient in this regard.

> Are you extracting the bounding box with completeRelations=yes
> completeWays=yes?

No, as I use quite generous bounds, I have not yet noticed a need for this. This is what I use:

OSM="de-bb.osm"
#
osmosis --read-xml enableDateParsing=no  file="europe.osm" --bounding-box left=5 right=16 top=56 bottom=47 --write-xml file=$OSM

After that I run splitter on the extract.

Perhaps you're trying to do too much at once?

Cheers.