[mkgmap-dev] Commit: r2477: Avoid that multipolygon cutting algorithm creates very small polygons

Thu Feb 7 14:01:25 GMT 2013

On 07.02.2013 13:31, GerdP wrote:
> Felix Hartmann-2 wrote
>> Well, I just tried it out with min-size-polygon=12 instead of 18, then
>> it works quite nicely. So the sea polygon parser is still cutting rather
>> small sea polygons. It should rather be the opposite way around I
>> suppose though. Through away small islands instead of throwing away the
>> sea.
>>
>> This is using:
>> --generate-sea --precomp-sea=\maps\sea
> It is the filter that throws away small shapes. The cut algo just creates
> sea and land shapes
> which cover  the whole area. Later, the shape size filter throws away small
> shapes, no matter
> what they are.
> So, until WanMil has finished the work on the new mp-cut branch you should
> see better results if you use the default for min-size-polygon (8) or even a
> smaller value.
>
> Gerd
>
My thinking was more, I want to have rather sea than land. So throw away 
small islands, instead of throwing away sea. So run a filter throwing 
away islands first IF the area is covered by precompiled sea. I'ld have 
to give it a try again, but I'm pretty sure that the old sea-generation 
not using precompiled sea, worked much more like this and did rather 
drop islands than sea (or rather flood things, than miss sea).