[mkgmap-dev] small issue with Way.getCofG()

Tue Jan 6 15:15:55 GMT 2015

Hi Mike,

50% sounds better than my algo, but still quite a lot. I'll have a closer look at your
algo later.
Please note that your change has a side effect on the house number generator.
Up to now this doesn't contain a filter for generated POI, so each polygon
with a house number is processed twice, once because of the POI, once
because the Generator uses Way.getCofG(). If both have different positions
this might have a negative impact.

Gerd

From: mike at tvage.co.uk
To: mkgmap-dev at lists.mkgmap.org.uk
Date: Tue, 6 Jan 2015 14:56:30 +0000
Subject: Re: [mkgmap-dev] small issue with Way.getCofG()

I have a working solution for ensuring that the created point is placed
within the polygon when using --add-pois-to-areas, based on drawing the
polygon on to a small monochrome bitmap and then looking for the point that
is furthest from the surrounding area. I used a 9x9 bitmap for polygons
having a small number of points and 15x15 for longer polygons. There is
however a performance penalty. My standard map takes about 1 hour 20
minutes; using this algorithm the time increases by about 50% to about 2
hours. I am not currently able to commit changes to SVN (perhaps someone can
help out with that) but I have attached the code changes. I suggest that due
to the performance penalty, if we adopt this, then the --add-pois-to-areas
option be extended to be --add-pois-to-areas[=centre|optimised] or something
similar, with the default being centre and functioning as now and the
optimised option invoking the new code. Please try out the suggested change.
Note I don't expect this to work properly where a polygon is formed from a
multiploygon relation, but the code could quite easily be adapted for this
circumstance.

Regards,
Mike

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