Hi.
I made a few tests to lower the size of the maps.

Comparison is made to my standard map which is based on the styles example in
mkgmap but extended a bit for my purposes. This has 100 % size.
There are 4 levels, 24 is the most detailed resolution.

Setting the resolution to 23 and changing relevant polygons, lines, points to
show at 23 instead of 24. 4 levels (option file).
Size 78 %.

Setting the resolution to 23 and changing relevant polygons, lines, points to
show at 23 instead of 24. 3 levels (option file). levels = 0:23, 1:20, 2:18
Size 64 %.


Using my minimal style (discussed earlier in this thread).
Compared to normal map, it is about 75 % in size.

Using minimal style and 
Setting the resolution to 23 and changing relevant polygons, lines, points to
show at 23 instead of 24. 4 levels (option file).
Size 63 %.

Using minimal style and 
Setting the resolution to 23 and changing relevant polygons, lines, points to
show at 23 instead of 24. 3 levels (option file). levels = 0:23, 1:20, 2:18
Size 51 %.


I noted that when resolution is set to 23 polygons smaller than the mentioned
raster at ~4.8 m disappear. They also do get distorted. Buildings are such
polygons that are effected a lot, and it is (in my opinion) a good idea to
disable buildings and similar polygons entirely when lowering the resolution.
Coast lines and alike become less detailed of course.
Some line segments have become a bit misaligned (i noted bus stop platforms
and similar short lines can have this issue).


I yet have to check how well these maps work on a unit but it seems possible
to lower the size quite a lot if it is desired.


Regards
Karl




On onsdag 30 december 2020 kl. 13:27:06 CET Vuki wrote:
> Hi,
>
> am also working on a "lite" style and there may be some nice idea in yours
> to use :) will check that out, thanks!
>
>
> Köszi:
> Vuki
> On 2020.12.30. 12:08, 7770 wrote:
>
> Hi.
> I am ok with sharing the style, but i was not able to do it until today
> (planned today or tomorrow).
> 5 files attached, 4 related to style, 1 to TYP (foskan.txt).
> Only those 4 style files have changes, compared to the standard.
>
> The complete set of files is ./mkgmap-rNNNN/examples/styles/default/
>
>
> There is nothing fancy nor complex, nor have i played around with the levels
> yet.
>
> For reference i also added my TYP-file, which may help in case you find some
> type codes which are non standard (there might be a few). The type file is
> shared and does contain a few things that are not used by the minimal style
> (don't get confused).
>
>
> Summery of the style, which is based on the default mkgmap example.
> All changes comments are marked with ## to be able to tell them apart from
> regular comments given after #.
>
> polygons and points do have a lot of disabled information.
> Buildings, shops, and most of the parking types are disables.
>
> lines doesn't have as many changes and probably a few more small waterways
> (streams, rapids, waterfalls) can be disabled to remove yet a bit of data.
>
> note for polygons.
> Waters and forests are still visible, since it adds information to the map,
> but if natural objects are not important for you, there is more space to
> save.
>
> i have made one change in lines file to display the road name on tertiary
> roads instead of the reference. this does make sense in nordic countries,
> where tertiary roads are usually only referred to with the name.
>
> Ski lifts (arealways in general) are set in similar way as railroads.
>
> One last thing to mention is that i have updated the inc/address file.
> Close to the end there is a section in which the mkgmap:phone is updated to
> show information about which fuels are sold at fuel stations. This is not
> fully complete for all fuel types but the ones i somehow considered
> important. Depending on where one is, a few more fuel types can easily be
> added.
>
> A note.
> The mkgmap:phone seems to be 50 characters maximum, longer data will be
> truncated and not shown on the device it seems.
>
>
> Regards and happy new year!
> Karl
>
> On onsdag 30 december 2020 kl. 10:16:51 CET Vuki wrote:
>
> Hi Karl,
>
> don't you want to share your minimal style? :)
>
>
> Köszi:
> Vuki
> On 2020.12.27. 20:59, 7770 wrote:
>
> Hi.
> A few observations about the TopoActive europe map. (i have it on a GPSMAP
> 66st).
>
> The map is rendered slower than most custom made maps.
> Updates occur 2 times per year, but even at those times many changes to OSM
> are not present. Perhaps they only update some parts yearly.
> Points lack all kind of additional information which other mappers add
> (opening hours, region, phone numbers, etc.).
> One nice thing is colour marked national parks and reserves.
> Being an outdoor map, it lacks some information about shelters in the
> wilderness.
> Routing is possible only for outdoor activities (cycle, walk, hike, direct),
> automotive routing (car, motorcycle) is disabled.
>
> I have tried creating a minimal style. This lowers the data to about 75 % or
> my normal set up. But i did not change the level, which i will try :-)
> Currently I am no way near the compression which TopoActive achieves. Using
> input data which is about 6,7 GB in pbf format, creates a gmapsupp just
> below 4 GB for normal and around 3 GB for minimal style. These numbers
> feels similar to getting France into 1.9 GB from 3.7 GB pbf (geofabrik).
>
>
> The minimal set up is not very fancy at all, it disables things not wanted.
> Buildings, shops, most of parkings, and a bit more.
>
> Today i cannot send off any style, but in case that would be of interest let
> me know and i can share it in a few days (guessing Wednesday or Thursday).
>
>
> Regards
> Karl
>
> On söndag 27 december 2020 kl. 20:08:10 CET Gerd Petermann wrote:
>
> Hi Pierre,
>
> my first guess would be that the level 0 is at resolution 23 instead of 24.
>
> Gerd
>
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von
> Pierre Brico <pierre.brico@gmail.com> Gesendet: Sonntag, 27. Dezember 2020
> 19:37
> An: Development list for mkgmap
> Betreff: [mkgmap-dev] Garmin Topo Europe map
>
>
> Hello guys,
>
> I've just discovered the Garmin TopoActive Europe map based on OpenStreetMap
> data. This map is sold at a price of 50€ or is pre-installed on some new
> devices. I've just seen it on the device of one of my friends and it looks
> very good. I'm surprised to see that for West Europe, it takes only 2.8GB
> and is quite complete (index for search, routable, ...).
>
> For now, I generate my own maps based on your excellent tool but the result
> is much bigger (1.9GB only for France with probably more details). So, my
> question is: does anybody have a similar configuration (style files and
> command line) to obtain a result like the Garmin TopoActive Europe ?
>
> Thanks,
> Pierre
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>
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