[PATCH] Reduce the resolution of natural=coastline
I would like to commit this patch, to bring natural=coastline to the same level with other water features (natural=water, landuse=reservoir, waterway=river). This patch would reduce the size of the Finland map by about 200 kilobytes and speed up map browsing at low resolution (wide zoom). With this patch, with full map detail on the Edge 705, both natural=water polygons and natural=coastline lines will be displayed at 30km or closer, and disappear at 50km or further. Any objections? Best regards, Marko
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. On 04.03.2010 13:10, Marko Mäkelä wrote:
I would like to commit this patch, to bring natural=coastline to the same level with other water features (natural=water, landuse=reservoir, waterway=river).
This patch would reduce the size of the Finland map by about 200 kilobytes and speed up map browsing at low resolution (wide zoom). With this patch, with full map detail on the Edge 705, both natural=water polygons and natural=coastline lines will be displayed at 30km or closer, and disappear at 50km or further.
Any objections?
Best regards,
Marko
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Felix Hartmann schrieb:
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.
For the setting of dp filter: Would it be a reasonable solution to take the settings from the options file of the style folder? I.e. in the style file should be a line like dpfilter = 0:12 1:20 2:50 3:100 similar to the resoltuion settings. With this it would be possible to set the filter for each resolution. Or would it be a better aproach to set this line at the commandline as a parameter? Regards, Johann
On 04.03.2010 20:03, Johann Gail wrote:
Felix Hartmann schrieb:
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.
For the setting of dp filter: Would it be a reasonable solution to take the settings from the options file of the style folder?
I.e. in the style file should be a line like dpfilter = 0:12 1:20 2:50 3:100 similar to the resoltuion settings. With this it would be possible to set the filter for each resolution.
Or would it be a better aproach to set this line at the commandline as a parameter?
Regards, Johann
I think it would be best like the resolution file. But it needs to be seperated by polygons and lines (there's already a patch "reducepolygonpointdensitypatch" to have different behaviour on roads vs polygons. It would just be needed to have additional settings for each resolution). Maybe it could be included into the resolution file in the style. (and if not given then put in some defaults. A little bit more ramp up should be default however). My ideal settings would be more or less (multiplied by the resolution bits, meaning the same correction as right now if I set e.g. 5.4, it shall correspond to that 5.4 as it is used currently, and not multiplied by the resolution bits)) - as for the resolutions I'm currently using: Resolution:linesdp/polygonsdp 0=24 -- currently not possible without breaking routing. A reduction of roads with very very dense points would be great however. No clue to which agressiveness dp filter would have to be setup. 1=22:2/2 2=21:4/6 3=20:6/9 4=19:8/13 5=18:9/15 6=16:10/20 (-- Ideally this would be inside the overview map) 7=14:15/30 (-- Ideally this would be inside the overview map)
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
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 _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
On Fri, Mar 05, 2010 at 12:16:46PM +0100, Felix Hartmann wrote:
Well for me any lake marked with natural=coastline is plain wrong. Just people mapping for the renderers.
Yes, but some controversy arised when I converted Saimaa (the biggest lake of Finland) to a number of multipolygons. It was simply too big (thousands of ways) for a single multipolygon, and even as it is now, Osmarender and OpenCycleMap are having trouble, especially around Kuopio.
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.
Agreed, it would be nice to see all big lakes at resolution 12. Could tuning the DP filter help realize that? Marko
participants (3)
-
Felix Hartmann -
Johann Gail -
Marko Mäkelä