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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
<refentry id='mkgmap-splitter'>
<refmeta>
<refentrytitle>mkgmap-splitter</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>mkgmap-splitter</refname>
<refpurpose>tile splitter for mkgmap</refpurpose>
</refnamediv>
<refsynopsisdiv id='synopsis'>
<cmdsynopsis>
<command>mkgmap-splitter</command>
<arg choice='opt'><replaceable>options</replaceable></arg>
<arg choice='plain'><replaceable><filename>file.osm</filename></replaceable></arg>
</cmdsynopsis>
> <replaceable><filename>splitter.log</filename></replaceable>
</refsynopsisdiv>
<refsect1 id='description'>
<title>DESCRIPTION</title>
<para>
<command>mkgmap-splitter</command> splits an .osm file that contains
large well mapped regions into a number of smaller tiles, to fit within
the maximum size used for the Garmin maps format.
</para>
<para>
The two most important features are:
<itemizedlist>
<listitem>
<para>
Variable sized tiles to prevent a large number of tiny files.
</para>
</listitem>
<listitem>
<para>
Tiles join exactly with no overlap or gaps.
</para>
</listitem>
</itemizedlist>
</para>
<para>
You will need a lot of memory on your computer if you intend to split a
large area.
A few options allow configuring how much memory you need.
With the default parameters, you need about 4-5 bytes for every node and
way.
This doesn't sound a lot but there are about 1700 million nodes in the
whole planet file and so you cannot process the whole planet in one pass
file on a 32 bit machine using this utility as the maximum java heap
space is 2G.
It is possible with 64 bit java and about 7GB of heap or with multiple
passes.
</para>
<para>
The Europe extract from Cloudmade or Geofabrik can be processed within
the 2G limit if you have sufficient memory.
With the default options europe is split into about 750 tiles.
The Europe extract is about half of the size of the complete planet file.
</para>
<para>
On the other hand a single country, even a well mapped one such as
Germany or the UK, will be possible on a modest machine, even a netbook.
</para>
</refsect1>
<refsect1 id='usage'>
<title>USAGE</title>
<para>
Splitter requires java 1.6 or higher.
Basic usage is as follows.
</para>
<screen>
<command>mkgmap-splitter</command> <replaceable><filename>file.osm</filename></replaceable> > <replaceable><filename>splitter.log</filename></replaceable>
</screen>
<para>
If you have less than 2 GB of memory on your computer you should reduce
the <option>-Xmx</option> option by setting the JAVA_OPTS environment
variable.
</para>
<screen>
JAVA_OPTS="<replaceable>-Xmx512m</replaceable>" <command>mkgmap-splitter</command> <replaceable><filename>file.osm</filename></replaceable> > <replaceable><filename>splitter.log</filename></replaceable>
</screen>
<para>
This will produce a number of .osm.pbf files that can be read by
<citerefentry>
<refentrytitle>mkgmap</refentrytitle>
<manvolnum>1</manvolnum>
</citerefentry>.
There are also other files produced:
</para>
<para>
The <filename>template.args</filename> file is a file that can
be used with the <option>-c</option> option of
<command>mkgmap</command> that will compile all the files.
You can use it as is or you can copy it and edit it to include
your own options.
For example instead of each description being "OSM Map" it could
be "NW Scotland" as appropriate.
</para>
<para>
The <filename>areas.list</filename> file is the list of bounding
boxes that were calculated.
If you want you can use this on a subsequent call the the
splitter using the <option>--split-file</option> option to use
exactly the same areas as last time.
This might be useful if you produce a map regularly and want to
keep the tile areas the same from month to month.
It is also useful to avoid the time it takes to regenerate the
file each time (currently about a third of the overall time
taken to perform the split).
Of course if the map grows enough that one of the tiles overflows
you will have to re-calculate the areas again.
</para>
<para>
The <filename>areas.poly</filename> file contains the bounding
polygon of the calculated areas.
See option <option>--polygon-file</option> how this can be used.
</para>
<para>
The <filename>densities-out.txt</filename> file is written when
no split-file is given and contains debugging information only.
</para>
<para>
You can also use a gzip'ed or bz2'ed compressed .osm file as the input
file.
Note that this can slow down the splitter considerably (particularly true
for bz2) because decompressing the .osm file can take quite a lot of CPU
power.
If you are likely to be processing a file several times you're probably
better off converting the file to one of the binary formats pbf or o5m.
The o5m format is faster to read, but requires more space on the disk.
</para>
</refsect1>
<refsect1 id='options'>
<title>OPTIONS</title>
<para>
There are a number of options to fine tune things that you might want to
try.
</para>
<variablelist>
<varlistentry>
<term><option>--boundary-tags=<replaceable>string</replaceable></option></term>
<listitem>
<para>
A comma separated list of tag values for relations.
Used to filter multipolygon and boundary relations for
problem-list processing.
See also option <option>--wanted-admin-level</option>.
Default: use-exclude-list
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--cache=<replaceable>string</replaceable></option></term>
<listitem>
<para>
Deprecated, now does nothing
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--description=<replaceable>string</replaceable></option></term>
<listitem>
<para>
Sets the desciption to be written in to the
<filename>template.args</filename> file.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--geonames-file=<replaceable>string</replaceable></option></term>
<listitem>
<para>
The name of a GeoNames file to use for determining tile names.
Typically <filename>cities15000.zip</filename> from
<ulink url="http://download.geonames.org/export/dump">geonames</ulink>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--keep-complete=<replaceable>boolean</replaceable></option></term>
<listitem>
<para>
Use <option>--keep-complete=false</option> to disable two
additional program phases between the split and the final
distribution phase (not recommended).
The first phase, called gen-problem-list, detects all ways and
relations that are crossing the borders of one or more output
files.
The second phase, called handle-problem-list, collects the
coordinates of these ways and relations and calculates all output
files that are crossed or enclosed.
The information is passed to the final dist-phase in three
temporary files.
This avoids broken polygons, but be aware that it requires to read
the input files at least two additional times.
</para>
<para>
Do not specify it with <option>--overlap</option> unless you have
a good reason to do so.
</para>
<para>
Defaulte: true
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--mapid=<replaceable>int</replaceable></option></term>
<listitem>
<para>
Set the filename for the split files.
In the example the first file will be called
<filename>63240001.osm.pbf</filename> and the next one will be
<filename>63240002.osm.pbf</filename> and so on.
</para>
<para>
Default: 63240001
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--max-areas=<replaceable>int</replaceable></option></term>
<listitem>
<para>
The maximum number of areas that can be processed in a single pass
during the second stage of processing.
This must be a number from 1 to 4096.
Higher numbers mean fewer passes over the source file and hence
quicker overall processing, but also require more memory.
If you find you are running out of memory but don't want to
increase your <option>--max-nodes</option> value, try reducing
this instead.
Changing this will have no effect on the result of the split, it's
purely to let you trade off memory for performance.
Note that the first stage of the processing has a fixed memory
overhead regardless of what this is set to so if you are running
out of memory before the <filename>areas.list</filename> file is
generated, you need to either increase your <option>-Xmx</option>
value or reduce the size of the input file you're trying to split.
</para>
<para>
Default: 512
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--max-nodes=<replaceable>int</replaceable></option></term>
<listitem>
<para>
The maximum number of nodes that can be in any of the resultant
files.
The default is fairly conservative, you could increase it quite a
lot before getting any 'map too big' messages.
Not much experimentation has been done.
Also the bigger this value, the less memory is required during the
splitting stage.
</para>
<para>
Default: 1600000
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--max-threads=<replaceable>value</replaceable></option></term>
<listitem>
<para>
The maximum number of threads used by
<command>mkgmap-splitter</command>.
</para>
<para>
Default: 4 (auto)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--mixed=<replaceable>boolean</replaceable></option></term>
<listitem>
<para>
Specify this if the input osm file has nodes, ways and relations
intermingled or the ids are not strictly sorted.
To increase performance, use the <command>osmosis</command> sort
function.
</para>
<para>
Default: false
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-trim=<replaceable>boolean</replaceable></option></term>
<listitem>
<para>
Don't trim empty space off the edges of tiles.
This option is ignored when <option>--polygon-file</option> is
used.
</para>
<para>
Default: false
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--num-tiles=<replaceable>value</replaceable>string</option></term>
<listitem>
<para>
A target value that is used when no split-file is given.
Splitting is done so that the given number of tiles is produced.
The <option>--max-nodes</option> value is ignored if this option
is given.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--output=<replaceable>string</replaceable></option></term>
<listitem>
<para>
The format in which the output files are written.
Possible values are xml, pbf, o5m, and simulate.
The default is pbf, which produces the smallest file sizes.
The o5m format is faster to write, but creates around 40% larger
files.
The simulate option is for debugging purposes.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--output-dir=<replaceable>path</replaceable></option></term>
<listitem>
<para>
The directory to which splitter should write the output files.
If the specified path to a directory doesn't exist,
<command>mkgmap-splitter</command> tries to create it.
Defaults to the current working directory.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--overlap=<replaceable>string</replaceable></option></term>
<listitem>
<para>
Deprecated since r279.
With <option>--keep-complete=false</option>,
<command>mkgmap-splitter</command> should include nodes outside
the bounding box, so that <command>mkgmap</command> can neatly
crop exactly at the border.
This parameter controls the size of that overlap.
It is in map units, a default of 2000 is used which means about
0.04 degrees of latitude or longitude.
If <option>--keep-complete=true</option> is active and
<option>--overlap</option> is given, a warning will be printed
because this combination rarely makes sense.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--polygon-desc-file=<replaceable>path</replaceable></option></term>
<listitem>
<para>
An osm file (.o5m, .pbf, .osm) with named ways that describe
bounding polygons with OSM ways having tags name and mapid.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--polygon-file=<replaceable>path</replaceable></option></term>
<listitem>
<para>
The name of a file containing a bounding polygon in the
<ulink url="">osmosis polygon file format</ulink>.
<command>mkgmap-splitter</command> uses this file when calculating
the areas.
It first calculates a grid using the given
<option>--resolution</option>.
The input file is read and for each node, a counter is increased
for the related grid area.
If the input file contains a bounding box, this is applied to the
grid so that nodes outside of the bounding box are ignored.
Next, if specified, the bounding polygon is used to zero those
grid elements outside of the bounding polygon area.
If the polygon area(s) describe(s) a rectilinear area with no more
than 40 vertices, <command>mkgmap-splitter</command> will try to
create output files that fit exactly into the area, otherwise it
will approximate the polygon area with rectangles.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--precomp-sea=<replaceable>path</replaceable></option></term>
<listitem>
<para>
The name of a directory containing precompiled sea tiles.
If given, <command>mkgmap-splitter</command> will use the
precompiled sea tiles in the same way as <command>mkgmap</command>
does.
Use this if you want to use a polygon-file or
<option>--no-trim=true</option> and <command>mkgmap</command>
creates empty *.img files combined with a message starting "There
is not enough room in a single garmin map for all the input data".
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--problem-file=<replaceable>path</replaceable></option></term>
<listitem>
<para>
The name of a file containing ways and relations that are known to
cause problems in the split process.
Use this option if <option>--keep-complete</option> requires too
much time or memory and <option>--overlap</option> doesn't solve
your problem.
</para>
<para>
Syntax of problem file:
</para>
<programlisting>
way:<id> # comment...
rel:<id> # comment...
</programlisting>
<para>
example:
</para>
<programlisting>
way:2784765 # Ferry Guernsey - Jersey
</programlisting>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--problem-report=<replaceable>path</replaceable></option></term>
<listitem>
<para>
The name of a file to write the generated problem list created with
<option>--keep-complete</option>.
The parameter is ignored if <option>--keep-complete=false</option>.
You can reuse this file with the <option>--problem-file</option>
parameter, but do this only if you use the same values for
<option>--max-nodes</option> and <option>--resolution</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--resolution=<replaceable>int</replaceable></option></term>
<listitem>
<para>
The resolution of the density map produced during the first phase.
A value between 1 and 24.
Default is 13.
Increasing the value to 14 requires four times more memory in the
split phase.
The value is ignored if a <option>--split-file</option> is given.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--search-limit=<replaceable>int</replaceable></option></term>
<listitem>
<para>
Search limit in split algo.
Higher values may find better splits, but will take longer.
</para>
<para>
Default: 200000
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--split-file=<replaceable>path</replaceable></option></term>
<listitem>
<para>
Use the previously calculated tile areas instead of calculating
them from scratch.
The file can be in .list or .kml format.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--status-freq=<replaceable>int</replaceable></option></term>
<listitem>
<para>
Displays the amount of memory used by the JVM every
<option>--status-freq</option> seconds.
Set =0 to disable.
</para>
<para>
Default: 120
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--stop-after=<replaceable>string</replaceable></option></term>
<listitem>
<para>
Debugging: stop after a given program phase.
Can be split, gen-problem-list, or handle-problem-list.
Default is dist which means execute all phases.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--wanted-admin-level=<replaceable>string</replaceable></option></term>
<listitem>
<para>
Specifies the lowest admin_level value of boundary relations that
should be kept complete. Used to filter boundary relations for
problem-list processing. The default value 5 means that
boundary relations are kept complete when the admin_level is
5 or higher (5..11).
The parameter is ignored if <option>--keep-complete=false</option>.
Default: 5
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--write-kml=<replaceable>path</replaceable></option></term>
<listitem>
<para>
The name of a kml file to write out the areas to.
This is in addition to <filename>areas.list</filename>
(which is always written out).
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
Special options
</para>
<variablelist>
<varlistentry>
<term><option>--version</option></term>
<listitem>
<para>
If the parameter <option>--version</option> is found somewhere in
the options, <command>mkgmap-splitter</command> will just print
the version info and exit.
Version info looks like this:
<screen>
splitter 279 compiled 2013-01-12T01:45:02+0000
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--help</option></term>
<listitem>
<para>
If the parameter <option>--help</option> is found somewhere in
the options, <command>mkgmap-splitter</command> will print a list
of all known normal options together with a short help and exit.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id='tuning'>
<title>TUNING</title>
<para>
Tuning for best performance
</para>
<para>
A few hints for those that are using <command>mkgmap-splitter</command>
to split large files.
</para>
<itemizedlist>
<listitem>
<para>
For faster processing with <option>--keep-complete=true</option>,
convert the input file to o5m format using:
<screen>
<command>osmconvert</command> <option>--drop-version</option> <filename>file.osm</filename> <option>-o=<filename>file.o5m</filename></option>
</screen>
</para>
</listitem>
<listitem>
<para>
The option <option>--drop-version</option> is optional, it reduces
the file to that data that is needed by
<command>mkgmap-splitter</command> and <command>mkgmap</command>.
</para>
</listitem>
<listitem>
<para>
If you still experience poor performance, look into
<filename>splitter.log</filename>.
Search for the word Distributing.
You may find something like this in the next line:
<screen>
Processing 1502 areas in 3 passes, 501 areas at a time
</screen>
This means splitter has to read the input file input three times
because the <option>--max-areas</option> parameter was much smaller
than the number of areas.
If you have enough heap, set <option>--max-areas</option> value to a
value that is higher than the number of areas, e.g.
<option>--max-areas=2048</option>.
Execute <command>mkgmap-splitter</command> again and you should find
<screen>
Processing 1502 areas in a single pass
</screen>
</para>
</listitem>
<listitem>
<para>
More areas require more memory.
Make sure that <command>mkgmap-splitter</command> has enough heap
(increase the <option>-Xmx</option> parameter) so that it doesn't
waste much time in the garbage collector (GC), but keep as much
memory as possible for the systems I/O caches.
</para>
</listitem>
<listitem>
<para>
If available, use two different disks for input file and output
directory, esp. when you use o5m format for input and output.
</para>
</listitem>
<listitem>
<para>
If you use <command>mkgmap</command> r2415 or later and disk space
is no concern, consider to use <option>--output=o5m</option> to
speed up processing.
</para>
</listitem>
</itemizedlist>
<para>
Tuning for low memory requirements
</para>
<para>
If your machine has less than 1 GB free memory (eg. a netbook), you can
still use <command>mkgmap-splitter</command>, but you might have to be
patient if you use the parameter <option>--keep-complete</option> and
want to split a file like <filename>germany.osm.pbf</filename> or a
larger one.
If needed, reduce the number of parallel processed areas to 50 with the
<option>--max-areas</option> parameter.
You have to use <option>--keep-complete=false</option> when splitting an
area like Europe.
</para>
</refsect1>
<refsect1 id='notes'>
<title>NOTES</title>
<itemizedlist>
<listitem>
<para>
There is no longer an upper limit on the number of areas that can be
output (previously it was 255).
More areas just mean potentially more passes being required over the
.osm file, and hence the splitter will take longer to run.
</para>
</listitem>
<listitem>
<para>
There is no longer a limit on how many areas a way or relation can
belong to (previously it was 4).
</para>
</listitem>
</itemizedlist>
</refsect1>
<refsect1 id='see-also'>
<title>SEE ALSO</title>
<citerefentry>
<refentrytitle>mkgmap</refentrytitle>
<manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>osmconvert</refentrytitle>
<manvolnum>1</manvolnum>
</citerefentry>
</refsect1>
</refentry>