Re: [mkgmap-dev] State of the coastline art

2010-04-01 Thread NopMap


Hi!

Just to let you know. Encouraged by your statements, I tried to do the
German coast along the baltic sea with --generate-sea=multipolygon. The map
was made up of 3 tiles.

The result was rather disillusioning. In about 1/4 of the coast it looked
good, on half of the coast the water was missing completely and about 1/4
was inverted with the land flooded and the sea clear.

My conclusion is that I'll stick to the old technique for the time being
(manually edited sea polygons derived from the shapefiles used by mapnik).

bye
  Nop

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Re: [mkgmap-dev] State of the coastline art

2010-04-01 Thread Apollinaris Schoell
What was the input? a geofabrik download or a osmosis extract with complete
coastline ways?
then you should try --generate-sea=extend-sea-sectors as Chris recommends.
I create all osm files with osmosis and  coastline will be complete and
touch tile boundaries.

another idea is to take the area.list from processing a germany extract and
feed it together with a planet or europe extract into splitter to get
complete coastlines.




On Thu, Apr 1, 2010 at 1:24 PM, NopMap ekkeh...@gmx.de wrote:



 Hi!

 Just to let you know. Encouraged by your statements, I tried to do the
 German coast along the baltic sea with --generate-sea=multipolygon. The map
 was made up of 3 tiles.

 The result was rather disillusioning. In about 1/4 of the coast it looked
 good, on half of the coast the water was missing completely and about 1/4
 was inverted with the land flooded and the sea clear.

 My conclusion is that I'll stick to the old technique for the time being
 (manually edited sea polygons derived from the shapefiles used by mapnik).

 bye
  Nop

 --
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 http://n2.nabble.com/State-of-the-coastline-art-tp4829364p4839472.html
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Re: [mkgmap-dev] State of the coastline art

2010-03-31 Thread Apollinaris Schoell
On Wed, Mar 31, 2010 at 12:30 AM, Marko Mäkelä marko.mak...@iki.fi wrote:

 On Tue, Mar 30, 2010 at 11:08:40PM -0800, NopMap wrote:
  - What level of confidence do you achieve with generate sea? Many posts
  still mention minor failures, disappearing islands etc.

 As far as I am concerned, it just works.  Any errors will be logged and
 will
 come through my error message filter.  You can fetch my scripts and files
 at
 http://www.polkupyoraily.net/osm/ and adapt to your area.


can confirm that. now also --generate-sea=multipolygon works and didn't have
any failures on whole california which has some real complex coastlines.
don't remember the exact mkgmap version. any newer one will do.
I like it more this way because I don't need to have a typ file


 Also, when debugging coastline errors (gap in coastline, coastline not
 extending to map border), you may want to use a command like this:

 osmosis --rx finland.osm.bz2 --tf accept-ways natural=coastline --used-node
 \
 --wx finland-coastline.osm


xapi is your friend and can achieve the same without downloading the planet
or excerpts
wget
http://www.informationfreeway.org/api/0.6/way\[natural=coastline\]\[bbox=-124.5,32,-114,42\]-O
coastline.osm


 The resulting file should be so small that you can load it in JOSM
 to see the way and node ids of the broken coastlines.

  - Is it possible to save the resulting sea/land polygons for later
 re-use?
  Apparently the OSM data changes more frequently than the actual coastline
  and re-generating it from scratch every time you update is not necessary.

 Generating the coastline is not that slow any more.  If you absolutely
 wanted,
 I guess you could generate a separate map layer with just the sea, and
 compile
 your regular map without --generate-sea.

Marko
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Re: [mkgmap-dev] State of the coastline art

2010-03-31 Thread Marko Mäkelä
On Wed, Mar 31, 2010 at 09:27:19AM -0700, Apollinaris Schoell wrote:
  Also, when debugging coastline errors (gap in coastline, coastline not
  extending to map border), you may want to use a command like this:
 
  osmosis --rx finland.osm.bz2 --tf accept-ways natural=coastline --used-node
  \
  --wx finland-coastline.osm
 
 
 xapi is your friend and can achieve the same without downloading the planet
 or excerpts
 wget
 http://www.informationfreeway.org/api/0.6/way\[natural=coastline\]\[bbox=-124.5,32,-114,42\]-O
 coastline.osm

Yes, xapi can be useful if you are interested in particular features, but it
won't help you in debugging a problem with a particular planet extract.
The data may have changed since the extract was taken, or the extract may
not completely contain some features.  I prefer to work with extracts, because
I don't have access to a fast mirror of the OSM database that would quickly
produce country-size map extracts on demand.

Someone pointed out to me that the Geofabrik cutting polygons aren't set in
stone.  Indeed, I emailed Frederik Ramm today, and he promptly sent me the
boundary polygon in JOSM format.  I edited it slightly in order to exclude
or include a few islands, and sent it back.  It will be interesting to see
if tomorrow's extract works out of the box (with the exception of tweaking
the endpoints of the mainland coastline).  If not, in a few iterations it
will.  (Now that I think of it, I should also fix the broken lake
multipolygons near the Finnish-Russian border by editing the Geofabrik
cutting polygon.)

Marko
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