Am 23.10.2012 09:59, schrieb Gerd Petermann:
Hi Carlos,
> I've seen problematic_polygons file in growing quite fast in the wiki.
> May it affect splitter performance? If so, would it make sense to split
> the file by continents or countries?
regarding performance:
a) if you specify the --problem-file parm, splitter has to do a lot
more work, so that affects performance, no matter how many ids you put
ino your list.
b) I don't expect a measurable performance impact for any id that does
NOT occur in your input OSM file(s) as long as this list doesn't contain
millions of ids. The information is stored in HashMaps, so the only
negative impact is a higher possibility of hash collisions and a
slightly higher
memory usage for these HashMaps. Most of the additional time that is
required to handle the list is caused by the fact that splitter has to
read the input
file more often (3 times). With o5m and pbf format, only parts of the
file(s) are read, with XML input the complete file is processed.
Of course, those ids that occor in your input data will require more
heap and probably produce more output data, so that will affect
performance.
OK?
The bigger problem that I see is this:
The list now contains some relations like
rel:52822 # Border Sweden
rel:1059668 # Border Norway
If you use the complete list to split e.g. finland.osm.pbf, the input
file will only contain parts of the needed data for these polygons.
I wonder what splitter should do in these cases?
Currently it might print a few messages regarding missing nodes or
ways, but it will use the incomplete data and it might
write the incomplete relation to more tiles than r202, thus mgkmap
might produce even more error messages.
I think it would be better to change this so that splitter returns to
the default handling for every relation or way that is not
complete, with a corresponding message.
Would that be better?
I think splitter should write everything he could find in input-data to
each tile. The intention is a "complete" boundary. Of course if you only
create a map of Finland, border of Sweden would only partly in the map,
but these lines shouldn't be broken.
But is this a new problem? I think the relation of eg. Sweden would be
written to a tile containing a part of Swedish boundary and there are
also missing ways and nodes.
@Carlos: Maybe it would be better to separate the wiki-list in several
parts like ferry, boundary, lakes, forrest. So it is easier to find out,
if the ID is already in the list.
Henning
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