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[mkgmap-dev] Split gmapsupp.img

From Felix Hartmann extremecarver at gmail.com on Fri Oct 23 11:46:51 BST 2020

Yes this would work. Of course if mkgmap could group by region instead of
by map-id it would be better - because then you could maybe just load two
of the gmapsupp.img or a single one instead of all.
The simplest approach would be that mkgmap just takes from *0001 to 0xxx
until 3600 or 3700MB filesize is reached - then add the mdr/mdx and put it
into a gmapsup1.img, then gmapsup2.img for the next 3700MB.

Or maybe mkgmap splitter could be changed to group the tile numbers a bit
more intelligently?
my approach would be
4 gmapsupp regions

9 gmapsupp regions

12 regions
1 2 4 7
3 5 810
6 91112

because splitter doesn't know how big a tile will be - give an average
value as option - I have 7MB per tile on average. So to be safe use
3200/7=457 - meaning 457 tiles per gmapsupp region. but I'm not sure if
such a raster is possible or maybe way too difficult to program.
My europe map is now about 23GB in size. So I guess in 2 years it will not
fit a single microSD anymore anyhow (because some space should be left for
other data).
Also of course a simple overview map about the regions then would be great.
But then the effort gets bigger and bigger. So maybe forget about all of
this and simply create gmapsupp by tile number until 3700MB. KISS
Then for Europe one could create 4 regions with OSMcut - and create 4 part
Europe each part overlapping 200km or so. Each part then would be usable or
many years. I kinda feel like up to 12-16GB of mapdata is not slowing down
devices too much. However right now with the 4GB limit it would be too many
maps to compile.

On Fri, 23 Oct 2020 at 10:39, Gerd Petermann <
gpetermann_muenchen at hotmail.com> wrote:

> Hi Felix and Carlos,
> sorry, I am a bit lazy here because it's no fun to wait many minutes or
> hours for a result while my machine is barely usable...
> My current assumption is this:
> You use splitter to split e.g. Europe or Asia or Africa. You either split
> with a given split-file or you let splitter calculate the tiles each time
> you are splitting.
> The resulting OSM files are compiled and give a set of tiles, e.g. from
> 47110001.img to 47113456.img, all located in the same directory.
> You want to compile one or more gmapsupp files for this set. A single
> gmapsupp would be created with e.g.
> java -Xmx4G -jar mkgmap.jar --gmapsupp --no-tdbfile --index
> --description=MyMap family-id=4711 [... other options] 4711*.img My.TYP
> but that would be too large. Let's assume the size of all the 4711*.img
> files is > 4 G and below 6G my simple approach would be something like this:
> set options=--gmapsupp --no-tdbfile --index --description=MyMap
> family-id=4711 [... other options]
> java -Xmx4G -jar mkgmap.jar %options% 47110*.img 47111*.img My.TYP
> ren gmapsupp.img gmapsupp1.img
> java -Xmx4G -jar mkgmap.jar %options% 47112*.img 47113*.img My.TYP
> ren gmapsupp.img gmapsupp2.img
> This creates 2 files containing all the tiles, each probably < 4G.
> Does this work? If yes, I have an idea how to change mkgmap.
> @Felix: My test with MapInstall produced three files for a selection of
> ~6G, each between 2G and 2.5G.
> Gerd
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von
> Gerd Petermann <gpetermann_muenchen at hotmail.com>
> Gesendet: Mittwoch, 21. Oktober 2020 15:50
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] Split gmapsupp.img
> Hi Andrej,
> great thanks, that seems to work fine.
> Gerd
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von
> Andrzej Popowski <popej at poczta.onet.pl>
> Gesendet: Mittwoch, 21. Oktober 2020 15:40
> An: mkgmap-dev at lists.mkgmap.org.uk
> Betreff: Re: [mkgmap-dev] Split gmapsupp.img
> Hi Gerd,
> empty usb drive is treated as a SD card, where only single gmapsupp.img
> is supported. Try to copy \Garmin\GarminDevice.xml from a GPS to
> pendrive, then MapInstall will treat it as a real GPS.
> There is other possibility. Select an empty folder on your HDD, unpack
> there files from attached archive and execute vgps-install.bat. This
> will create some config for MapInstall, which will use your selected
> folder as a destination for maps. You can then remove installation files
> from the folder.
> --
> Best regards,
> Andrzej
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Felix Hartman - Openmtbmap.org & VeloMap.org
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