[mkgmap-dev] Option to output polygons in size order

Wed Jul 27 12:41:57 BST 2016

Hi Felix,

okay, maybe I'll add this as an experimental option as well.

One big question here is: At what point would the cutting

happen? Before style processing (as we do with mp-relations)

or maybe as a new stage before the img data is written.

What I don't yet understand is the idea that a smaller

polygon is more important. Do you have examples for that,

esp. cases where shapes do only partially overlap?

Gerd

________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Felix Hartmann <extremecarver at gmail.com>
Gesendet: Mittwoch, 27. Juli 2016 13:24:37
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] Option to output polygons in size order

On 27 July 2016 at 09:29, Gerd Petermann <GPetermann_muenchen at hotmail.com<mailto:GPetermann_muenchen at hotmail.com>> wrote:

reg. the idea of "cutting out overlaps": I guess it would consume quite a lot of CPU and it would heavily increase the img size

because we would have to write many more points. Think of a shape for "place=village" with hundreds of holes for each building

shape. Up to now we save the shape for the village and the shapes for the buildings. With cutting we have to calculate what

remains of the village shape, this would be a very complex shape with many holes, so it would have many points.

I don't think that would be a good idea.

Well that's why I wrote we will need an additional file in the style-file for this. So only for certain polygons this should be done.
Prime examples are: any kind of forest, most kind of water, and maybe a handful more. However definitely not buildings or for example poygons you can put semi-transparent.

I'm quite sure with this limited approach 90% of problems would be gone. And mapsize only a couple percent bigger. However I have no clue about complexity and CPU cycles for such a limited approach.

--
Felix Hartman - Openmtbmap.org & VeloMap.org
Schusterbergweg 32/8
6020 Innsbruck
Austria - ?sterreich
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