[mkgmap-dev] Bay polygons points conversion

Fri Dec 20 18:01:07 GMT 2019

Hi all,

reg. search: I think Garmin maps allow to search for some polygons, but mkgmap doesn't add them to the global index.
For the experts: The MDR file has groups >= 64 (or was it 0x64?) for named polygons, I think I saw that in at least one of
the demo maps using display tool MdrDisplay.
I did not dig into the details because probably everybody uses --add-pois-to-areas and thus we would just double the information in the index.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
Gesendet: Freitag, 20. Dezember 2019 18:33
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] Bay polygons points conversion

Hi David

If I understand you correctly, you don't want duplication of an element
as both a polygon and a POI, and, for all elements except 'bay', you
want the polygon if define as such by OSM, but not the POI as well, but
for 'bay', you want a POI only, regardless of it maybe being defined in
OSM as a polygon.

Assuming this is the case, then what you have is a way of doing it.
Another would be something like, at the top of points:

natural=bay [0x6503 resolution 18]
mkgmap:area2poi=true {deletealltags}

But:
1/ it seems strange that you single out bays for this treatment.
2/ searching by name and showing nearby POI will be very inconsistent,
ie depend on if OSM defined them as a point or polygon
3/ 3mb is not much extra in an .img file

Ticker

On Fri, 2019-12-20 at 16:47 +0000, Gerd Petermann wrote:
> Hi David,
>
> not sure but it sounds like a missunderstanding.
> The --add-pois-to-areas option generates a node for each polygon, but
> the rules in the points file decide if a POI is added to the map for
> such a node.
> So, if you remove the natural=bay from the polygon rules there is no
> need to distinguish between generated natural=bay nodes or real OSM
> nodes with that tag.
>
> Gerd
>
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von David <david.tlp at orange.fr>
> Gesendet: Freitag, 20. Dezember 2019 17:06
> An: mkgmap-dev at lists.mkgmap.org.uk
> Betreff: [mkgmap-dev] Bay polygons points conversion
>
> The if else is needed in my case because the option « add-pois-to
> -areas » adds at least one point for each polygon/multipolygon. For
> example, if a polygon is used to display a named hospital, you will
> then have also a point with the same name. As explained in the
> documentation, it makes possible to search the hospital. For Ireland,
> adding pois to polygons adds at least 3Mb more to the final img file.
> In Qmapshack, the name of extra POIs is displayed. With the if
> statement, I do not render bay polygon in polygons style file but I
> add a corresponding POI in points style file only for bays.
>
> This simple trick may need few lines in the documentation.
>
> But, I think the problem is that a bay is an inner part of something
> bigger (like an administrative area is a part of a country). As we do
> not render counties with a special polygon, bay should not be
> rendered because they are parts of ocean or sea with no really
> borders. Last point the style 0x3d chosen for bays is in Garmin
> Europe map and other Garmin products used for lakes with a size
> between 77 and 250 km2. 0x3b and 0x45 are known as to be blue like
> sea polygon and correspond to « unknown ».
>
> David
>
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