[mkgmap-dev] more refined mkgmap:skipSizeFilter=true handling

Wed May 15 11:05:47 BST 2013

Hi,

Felix Hartmann-2 wrote
> (also I still don't understand, why mkgmap makes so small squares for 
> the sea, instead of larger squares - which should also save on .img size).

I've committed r2610 in the overview2 branch which generates fewer polygons.
It combines land-only and sea-only polygons first. This seems to improve
speed and 
decreases the img size.

There is still one problem left:
The SeaGenerator uses a raster of 32768 map units, means, it is very likely
to generate polygons
with a max dimension of 32768. The maximum allowed value in mkgmap is 0x7fff
(32767), 
so many of the polygons created by the SeaGenerator are split into smaller
parts just because of this
one map unit.

In some sources we use the test <= 0x7fff, in others < 0x7fff.
If I got this right, the limit is not really the size of the polygon, but
the largest offset from
any of its points to the center of the sub division. With a max dimension
less than 0x7fff we just 
make sure that this offset can't be > 0x7fff.
So, it might be possible to allow a max dimension of 327678 if we make sure
that the sub division center is not too far away from the center of the
largest polygon in it. 

Gerd

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