[mkgmap-dev] mkgmap ToDo list

Wed Apr 30 10:49:34 BST 2014

I would love if there was a possibility that you pass the used max-nodes 
value to mkgmap.
When mkgmap is compiling the maps, then after the .img is created it 
should check
a) did it crash due to too many max-nodes
b) for me not important - but for others with very old GPS, etrex 10, 
---> is tile bigger than X (usually 8) MB.

if a) or b) true, then pass the file back to splitter and split with 60% 
of maxnodes - and compile the resulting .img files again. Should it fail 
again, use 40%, again 25%... Sometimes there are awful tiles, that need 
supersmall max-nodes till they compile, however lately (last 1-2 years) 
I never encountered them anymore. I think that happened rather due to a 
but in splitter/mgkmap that is fixed now.

okay, you could also do this with a script, but it gets rather 
complicated to multithread it (you need to wait till mgkmap finished 
compiling all .img files - and run mkgmap first without address index to 
save time) and do some clever routines on making sure that the map id 
(e.g. 6340????.img)  stay correct. Even more complicated to have 
consequent map id...

For europe with a fixed max-node I get tiles from 1.9MB up to 18MB. 
That's factor 9 - so it's huge...
If I could narrows that down easily to 8-18MB - without getting tiles 
crashing due to too high max-nodes values, that would be sweet.

As for the scripts - would they run on windows too? - What programming 
language are they in?

On 29.04.2014 21:39, osm at na1400.info wrote:
> Oh, and ofcourse anyone interested can get my scripts, send an email. 
> They'll be on Github someday anyway.
>
>
> On 2014-04-29 20:37, Gerd Petermann wrote:
>> Hi Lambertus,
>>
>> okay, if I got that right you finally get *.img files with a size
>> near (but below) 8MB, so maybe Henning can use that script, too.
>>
>> If you do that for e.g. Germany, how small is tpically the smallest
>> *.img file ?
>> Is it probably near 4 MB?
>>
>> Gerd
>>
>>> To: mkgmap-dev at lists.mkgmap.org.uk
>>> Date: Tue, 29 Apr 2014 20:30:27 +0200
>>> From: osm at na1400.info
>>> Subject: Re: [mkgmap-dev] mkgmap ToDo list
>>>
>>> These are the direct results from Splitter. The format is o5m, both
>>> input as output. Splitter version is: r321.
>>>
>>> For this test I split the original source with --max-nodes=8000000.
>> Then
>>> I render the initial tiles, when the result is larger than 8MB it's
>>> subsplit again with --max-nodes=(8000000-(attempt*100000)). The
>> initial
>>> source files are ~70MB (o5m) and after several subsplits the two
>> *.img
>>> are < 8MB. During this process --max-nodes has been reduced to e.g.
>>> 7500000 and the source file is split up in two o5m files of about
>> 37MB.
>>>
>>> I can upload an example source file and it's two subsplit siblings
>> if
>>> you want.
>>>
>>>
>>> On 2014-04-29 19:38, GerdP wrote:
>>> > Hi Lambertus,
>>> >
>>> > that's interesting. Are these the img file sizes or the osm file
>> sizes?
>>> >
>>> > Gerd
>>> >
>>> >
>>> > Lambertus wrote
>>> >> Unfortunately I cannot confirm that. Below is a bit of logging
>> from my
>>> >> script:
>>> >> Original: 97000020 (70551453), New: 0 (35684445), New: 1
>> (36852845)
>>> >> Original: 97000001 (74621042), New: 0 (37522992), New: 1
>> (37222739)
>>> >> Original: 97000002 (73391358), New: 0 (37679505), New: 1
>> (38098627)
>>> >> Original: 97000003 (77862567), New: 0 (39075311), New: 1
>> (39261197)
>>> >>
>>> >> The original files above contain contour data, the filesize is
>> between
>>> >> brackets. As you can see both resulting file are approximately
>> the
>>> >> same
>>> >> size.
>>> >>
>>> >> On 2014-04-29 15:39, Gerd Petermann wrote:
>>> >>> Hi Lambertus,
>>> >>>
>>> >>> and I guess that even after this optimization you will
>>> >>> see a factor 3 or higher between the largest tile and the
>> smallest.
>>> >>> Can you confirm that?
>>> >>>
>>> >>> Gerd
>>> >>>
>>> >>>> Date: Tue, 29 Apr 2014 15:32:38 +0200
>>> >>>> From:
>>> >
>>> >> osm@
>>> >
>>> >>>> To:
>>> >
>>> >> mkgmap-dev at .org
>>> >
>>> >>>> Subject: Re: [mkgmap-dev] mkgmap ToDo list
>>> >>>>
>>> >>>> Num-tiles=x would indeed be better for this specific need.
>>> >>>>
>>> >>>> It is my experience that it regularly takes multiple calls to
>>> >>> Splitter
>>> >>>> to get 2+ sub-tiles when you reduce the max-nodes by 100k for
>> each
>>> >>>> sub-split attempt. This is what I currently do to get an
>> optimum in
>>> >>>> tile-size vs total number of tiles.
>>> >>>>
>>> >>>>
>>> >>>>
>>> >>>> On 29/04/2014 15:09, Gerd Petermann wrote:
>>> >>>> > Hi Lambertus,
>>> >>>> >
>>> >>>> > that sounds like a possible change in splitter:
>>> >>>> > Instead of specifying max-nodes you may specify --num-tiles=x
>>> >>>> > and splitter will try to find a split that produces excactly
>> x
>>> >>> tiles
>>> >>>> > which are not too narrow and have a node number which is not
>>> >>>> > too far from the average (but still aligned to a multiple of
>> map
>>> >>> units
>>> >>>> > as now).
>>> >>>> > So, for your script that means you don't have to find the
>>> >>> max-nodes
>>> >>>> > value.
>>> >>>> >
>>> >>>> > I'll think about this again...
>>> >>>> >
>>> >>>> > Gerd
>>> >>>> >
>>> >>>> > > Date: Tue, 29 Apr 2014 14:59:36 +0200
>>> >>>> > > From:
>>> >
>>> >> osm@
>>> >
>>> >>>> > > To:
>>> >
>>> >> mkgmap-dev at .org
>>> >
>>> >>>> > > Subject: Re: [mkgmap-dev] mkgmap ToDo list
>>> >>>> > >
>>> >>>> > > While this possibly can be solved in Splitter or Mkgmap, it
>>> >>> could also
>>> >>>> > > be solved by your build-script when you add a maximum tile
>> size
>>> >>> check
>>> >>>> > > and re-split (with a lower number of max-nodes) until you
>> get
>>> >>> two or
>>> >>>> > > more sub-tiles. Granted, this adds complexity to the script
>> but
>>> >>> it works
>>> >>>> > > well for me.
>>> >>>> > >
>>> >>>> > > On 25/04/2014 21:54, Henning Scholland wrote:
>>> >>>> > > > Hi Gerd,
>>> >>>> > > >
>>> >>>> > > > I would like to have img-tiles which have globally nearly
>> the
>>> >>> same
>>> >>>> > > > filesize, so that they use the space of devices like
>> eTrex 10.
>>> >>>> > > >
>>> >>>> > > > With my actual map I use globally the same value for
>>> >>> max-nodes. But the
>>> >>>> > > > size of the img-tiles differ more then factor 2. Eg. a
>> tile in
>>> >>> Germany
>>> >>>> > > > is between 2 and 5 mb where a tile in China is about 10
>> mb. If
>>> >>> I remove
>>> >>>> > > > details, this difference will increase, because in
>> Germany
>>> >>> more objects
>>> >>>> > > > will be removed from the img-tile then in China.
>>> >>>> > > >
>>> >>>> > > > Henning
>>> >>>> > > >
>>> >>>> > > > _______________________________________________
>>> >>>> > > > mkgmap-dev mailing list
>>> >>>> > > >
>>> >
>>> >> mkgmap-dev at .org
>>> >
>>> >>>> > > > http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
>>> >>>> > >
>>> >>>> > > _______________________________________________
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>>> >>>> > >
>>> >
>>> >> mkgmap-dev at .org
>>> >
>>> >>>> > > http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
>>> >>>> >
>>> >>>> >
>>> >>>> > _______________________________________________
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>>> >
>>> >> mkgmap-dev at .org
>>> >
>>> >>>> > http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
>>> >>>> >
>>> >>>>
>>> >>>> _______________________________________________
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>>> >
>>> >> mkgmap-dev at .org
>>> >
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>>> >>>
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>>> >
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>>> >
>>> >
>>> >
>>> >
>>> >
>>> > --
>>> > View this message in context:
>>> >
>> http://gis.19327.n5.nabble.com/mkgmap-ToDo-list-tp5803388p5804588.html
>>> > Sent from the Mkgmap Development mailing list archive at
>> Nabble.com.
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-- 
keep on biking and discovering new trails

Felix
openmtbmap.org & www.velomap.org