[mkgmap-dev] The 0x4b background polygon in the overview map

Fri Jan 12 12:16:19 GMT 2018

Hi Gerd,

I probably didn't got your issue.

So far I understand I gave mkgmap a list of data tiles or already
compiled map tiles. based on this mkgmap creates a complete map. At the
moment the overview map is rectangle of maxlat,maxlon,minlat,minlon.
Based on my suggestion user in future would be able to gave a different
polygon for overview map. If I let mkgmap use the tiles of Bremen, I
should use a matching bounding polygon. Of course if overview map is
larger than detailed map, the exceeding area will only have rough
sea/land area and DEM. In your example, if I use Germany.poly for Bremen
map, I will see rough DEM of Germany and North Sea and Baltic Sea cost
line (based on polygon). I wouldn't see an issue unless it's fine for
Garmin. Are you talking about generating a partial map with
BaseCamp/MapSource? I haven't checked how Garmin handle overview map in
that case.

I'm not sure, if Garmin supports smaller/larger overview maps then
detailed map area is available. That's why I was thinking about if we
need to gave some limits, like overview map shouldn't be larger than
actual rectangle or not covering all the detailed map area.

Henning

On 12.01.2018 19:43, Gerd Petermann wrote:
> Hi Henning,
>
> I don't think that we should apply a bounding polygon only to the overview map.
> If you compile tiles for whole Germany and produce a map for Bremen using
> some of these tiles and an overview map that was created with a proper polygon
> I would assume that this looks strange when you zoom in/out.
>
> I don't understand what you mean with maximizing/minimizing the polygon.
> Please explain.
>
> Gerd
>
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Henning Scholland <osm at hscholland.de>
> Gesendet: Freitag, 12. Januar 2018 12:35:04
> An: mkgmap-dev at lists.mkgmap.org.uk
> Betreff: Re: [mkgmap-dev] The 0x4b background polygon in the overview map
>
> Hi Gerd,
>
> I think this would be best and additionally I would suggest to make the
> polygon defined by user (as suggested in DEM-poly and precomp-sea
> thread). As default I would limit overview map to the map tiles. Maybe
> then we should name the parameter --overview-map-polygon=filename
>
> I'm not sure, if the actual rectangle should be maximizing the polygon
> and the map tile area minimizing it or if Garmin doesn't care at all
> about it. If no external sea-data is given I would keep map tile area as
> background polygon. Otherwise it will look strange.
>
> Henning
>
> On 12.01.2018 19:19, Gerd Petermann wrote:
>> Hi all,
>>
>> up to now mkgmap always creates a rectangular 0x4b polygon for the overview map. I wonder
>> if I should change that so that the 0x4b polygons of the sub tiles are used.
>> This seems to be the better way if we start using non-rectangular 0x4b polygons?
>>
>> Gerd
>> _______________________________________________
>> mkgmap-dev mailing list
>> mkgmap-dev at lists.mkgmap.org.uk
>> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
>>
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