[mkgmap-dev] Water polygons in default style

Mon Jun 8 07:37:01 BST 2015

Hi Carlos,

I have tested your proposals.

1) If I got that right the major difference is 
that the default style uses type 0x3c for natural=water+water=reservoir
and 0x3f for landuse=reservoir .
I agree that both should be treated the same, 
the change was committed with r3617 
(the svn comment is misleading, it only mentions the change in res)

I did not find a similar correspondance between landuse=basin and any of the 
water=* tags, so my proposal for this part would be to 
change the rule
landuse=basin|landuse=reservoir [0x3f resolution 20]
to
landuse=basin [0x3f resolution 20]
(landuse=reservoir | (natural=water & water=reservoir)) [0x3f resolution 20]

2) I am not sure about the part reg. area_size() usage. 
My understanding so far:
Garmin has different types for water polygons, 
GPSMapEdit shows them like this:

0x28: Sea/Ocean
0x29: Body of water  (invisible in Basecamp/MapSource ?)
0x32 : Sea
0x3b : Body of water (invisible in Basecamp/MapSource ?)
0x3c: Large lake (250-600 km²) 
0x3d: Large lake (77-250 km²) 
0x3e: Medium lake (25-77 km²)
0x3f: Medium lake (11-25 km²) 
0x40: Small lake (0.25-11 km²)
0x41: Small lake (<0.25 km²) 
0x42: Major lake (>3300 km²) 
0x43: Major lake (1100-3300 km²)
0x44: Large lake (600-1100 km²) 
0x45: Body of water (invisible in Basecamp/MapSource ?)

My Oregon 600 shows all polygon types
0x28 - 0x45 with the same blue color, so I 
think it is okay to use the same type for all water polygons
as long as we don't use a typ file.

Your changes reg. area_size() seem to remove visible details,
so I'd prefer not to use them.

3) It seems that 
natural=sea [0x32 resolution 10]
instead of 
natural=sea { add mkgmap:skipSizeFilter=true } [0x32 resolution 10]
has no effect. I assume it is obsolete now because of the 
ShapeMergeFilter, but it should do no harm either.

In short: 
My proposal for the new inc/water_polygons:
landuse=basin [0x3f resolution 20]
(landuse=reservoir | (natural=water & water=reservoir)) [0x3f resolution 20]

natural=bay [0x3d resolution 18]
natural=glacier [0x4d resolution 18]
natural=marsh [0x51 resolution 20]
natural=mud [0x51 resolution 20]
natural=wetland [0x51 resolution 20]

natural=water [0x3c resolution 18]
natural=waterfall | waterway=waterfall [0x47 resolution 21]
natural=sea { add mkgmap:skipSizeFilter=true } [0x32 resolution 10]

waterway=riverbank [0x46 resolution 20] 

Gerd

> Date: Fri, 5 Jun 2015 13:44:47 +0200
> From: cdavilam at orangecorreo.es
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: [mkgmap-dev] Water polygons in default style
> 
> According to wiki [1] landuse=reservoir and 
> natural=water+water=reservoir are equivalent, but the latter (and 
> preferred) form is missing in default style.
> Another thing to comment is that all water bodies are treated the same 
> in default style, despite they can vary from a few square meters (ponds) 
> to thousands hectares. I've been playing a bit with area_size() and 
> found some values that avoid too small water polygons at certain zoom 
> levels in MapSource (it may require some more test though).
> Below is current water_polygons file in my style. Do you think it's 
> worth including such rules in default style?
> landuse=basin|landuse=reservoir & area_size()>125000 [0x3f resolution 18]
> landuse=basin|landuse=reservoir & area_size()>35000 [0x3f resolution 20]
> landuse=basin|landuse=reservoir [0x3f resolution 22]
> 
> natural=bay [0x3d resolution 18]
> natural=glacier [0x4d resolution 18]
> natural=marsh [0x51 resolution 20]
> natural=mud [0x51 resolution 20]
> natural=wetland [0x51 resolution 20]
> natural=water & water=reservoir & area_size()>125000 [0x3f resolution 18]
> natural=water & water=reservoir & area_size()>35000 [0x3f resolution 20]
> natural=water & water=reservoir [0x3f resolution 22]
> natural=water & area_size()>125000 [0x3c resolution 18]
> natural=water & area_size()>35000 [0x3c resolution 20]
> natural=water [0x3c resolution 22]
> natural=waterfall | waterway=waterfall [0x47 resolution 21]
> natural=sea [0x32 resolution 10]
> 
> waterway=riverbank [0x46 resolution 20]
> 
> [1] http://wiki.openstreetmap.org/wiki/Key:water
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