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<p>Hi Felix,</p>
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<p>okay, I like the idea reg. layer, but I was not yet able to find an example in OSM.</p>
<p>I assume the problem appears only in specific regions wheres such an unexperienced</p>
<p>mapper is active. Do you know such a region?</p>
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<p>Gerd<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>Von:</b> mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Felix Hartmann <extremecarver@gmail.com><br>
<b>Gesendet:</b> Mittwoch, 27. Juli 2016 14:31:28<br>
<b>An:</b> Development list for mkgmap<br>
<b>Betreff:</b> Re: [mkgmap-dev] Option to output polygons in size order</font>
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<div>Well the smaller polygon in usual is the one that people expect to end up on top. HOWEVER - before even checking for size - there could be a check for the layer tag. It is still commonly used by people who do not understand how to use multipolygons.
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So an approach could be - take polygon overlap check for values defined in "overlap" style-file - after multipolgyon overlap is gone.<br>
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Check if layer tag is present on either of the polygons. If yes - then cut out according to layer.<br>
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If not - cut out the smaller from the bigger. Usually it's the smaller polygon that should appear.<br>
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I guess it needs to happen quite late therefore. Why smaller - well quite often people contacted me about islands missing/flooded or similar - and usually it was the smaller polygon that should have been on top. I guess with layer tag however 90% of all cases
can already be resolved. (I do this in a very limited way already - by having some polygons like water and forest in several versions with different priority based on layer tag - this did help a lot)<br>
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Felix<br>
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<div class="gmail_quote">On 27 July 2016 at 13:41, Gerd Petermann <span dir="ltr">
<<a href="mailto:GPetermann_muenchen@hotmail.com" target="_blank">GPetermann_muenchen@hotmail.com</a>></span> wrote:<br>
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<p>Hi Felix,</p>
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<p>okay, maybe I'll add this as an experimental option as well. <br>
</p>
<p>One big question here is: At what point would the cutting</p>
<p>happen? Before style processing (as we do with mp-relations)</p>
<p>or maybe as a new stage before the img data is written.</p>
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<p>What I don't yet understand is the idea that a smaller </p>
<p>polygon is more important. Do you have examples for that,</p>
<p>esp. cases where shapes do only partially overlap?<br>
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<p>Gerd<br>
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<div dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><span class=""><b>Von:</b> mkgmap-dev <<a href="mailto:mkgmap-dev-bounces@lists.mkgmap.org.uk" target="_blank">mkgmap-dev-bounces@lists.mkgmap.org.uk</a>> im Auftrag von
Felix Hartmann <<a href="mailto:extremecarver@gmail.com" target="_blank">extremecarver@gmail.com</a>><br>
</span><b>Gesendet:</b> Mittwoch, 27. Juli 2016 13:24:37<span class=""><br>
<b>An:</b> Development list for mkgmap<br>
<b>Betreff:</b> Re: [mkgmap-dev] Option to output polygons in size order</span></font>
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<div class="gmail_quote">On 27 July 2016 at 09:29, Gerd Petermann <span dir="ltr">
<<a href="mailto:GPetermann_muenchen@hotmail.com" target="_blank">GPetermann_muenchen@hotmail.com</a>></span> wrote:<br>
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<p>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<br>
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<p>because we would have to write many more points. Think of a shape for "place=village" with hundreds of holes for each building</p>
<p>shape. Up to now we save the shape for the village and the shapes for the buildings. With cutting we have to calculate what</p>
<p>remains of the village shape, this would be a very complex shape with many holes, so it would have many points.</p>
<p>I don't think that would be a good idea.</p>
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<div class="gmail_extra">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.<br>
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<div class="gmail_extra">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.<br>
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<div class="gmail_extra">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.<br>
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<div>Felix Hartman - Openmtbmap.org & VeloMap.org<br>
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Schusterbergweg 32/8<br>
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<div>6020 Innsbruck<br>
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Austria - Österreich</div>
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<div>Felix Hartman - Openmtbmap.org & VeloMap.org<br>
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Schusterbergweg 32/8<br>
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<div>6020 Innsbruck<br>
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Austria - Österreich</div>
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