[mkgmap-dev] [PATCH] Reduce the resolution of natural=coastline

Fri Mar 5 11:16:46 GMT 2010

Well for me any lake marked with natural=coastline is plain wrong. Just 
people mapping for the renderers.

A better solution would be, to simply have higher limits of how big a 
polygon needs to be at a certain resolution. As well as the DP filter 
aggressiveness, at resolutions lower than 20, we would need more 
aggressive dropping of small polygons.
Dropping coastline already at 18, is superstrange if one is using 
--generate-sea=polygons.

Everything is features we already have, they are just not yet dependant 
on resolution. Reducing sea to 18 from 16 is just a crutch (if the goal 
is to have faster map redraw) in comparison to more aggressive DP filter 
and larger minimum polygon size at lower resolutions. It's especially on 
resolutions 13-16 where ocean helps orientation and will be even more 
important once we have a non empty basemap for Mapsource.

On 05.03.2010 12:10, Marko Mäkelä wrote:
> Hi Felix,
>
> On Thu, Mar 04, 2010 at 04:50:34PM +0100, Felix Hartmann wrote:
>    
>> It would be better to have more aggressive dp-filter instead. As I
>> wrote a while back, the increase of the dp filter in low resolutions
>> has to be much higher. Currently a level of 10 is very good, but too
>> strong for resolutions 23-21 and a bit too strong for 20.
>>      
> Better compared to what?  Currently, all other water features are at
> resolution 18, while natural=coastline is at resolution=12.  Resolution 12
> means that all lakes that are mapped as natural=coastline will show up
> and seriously slow down the map drawing at wide zoom.  It is just plain
> illogical that some water features disappear but others do not.
>
> It could be nice to have presets for resolutions in the style file, so
> that you could say 'resolution water' in all map features and define
> 'water' as 18, for instance.
>
> 	Marko
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