[mkgmap-dev] Generate-sea oddities

Fri Jan 1 20:29:34 GMT 2010

Happy new year to all!  I begin it by looking in the gift horse's mouth,
trying to generate sea polygons for Finland.  Some oddities:

First, without --generate-sea, the lake at
http://www.openstreetmap.org/?mlat=60.620864&mlon=25.087002&zoom=14
is visible at all zoom levels from 5m to 2km.  With --generate-sea,
it is not visible between 5m and 500m but visible between 800m and 2km.
This could apply to all lakes; initially I did not find any nearby
lakes in the map.

Second, the coast line of the Åland archipelago is missing (it is all
yellow).

Third, much of the land and sea is inverted.
(i) At around lat=60.515400 lon=21.172457 there is the NW corner of a
rectangle that covers the SE corner of the southmost map tile.
Inside this box, the land and sea are reversed.
(ii) At around lat=60.515421 [same as (i)] lon=25.140496 there is the
NW corner of a rectangle.  West of the longitude, the background is
initially drawn as sea but later filled with yellow when the Edge 705
completes drawing.  East of the longitude, the background is initially
drawn as land but later filled as sea (light blue). 
(iii) Further corners of magic rectangles are at
lat=62.578126 [tile border] lon=21.172456 [same as (i)] and at
lat=64.819337 [tile border] lon=24.128254

The options are as at http://www.polkupyoraily.net/osm/, with one addition:
generate-sea: polygons,land-tag=natural=scrub

I can provide the gmapsupp.img if needed.  It looks the same in QLandKarteGT:
only the west coast north of (i) is OK in the north and south tiles,
and the middle tile is completely flooded.  The tiles are as follows:

63240001: 2768896,890880 to 2916352,1472512
#       : 59.414063,19.116211 to 62.578125,31.596680
63240002: 2916352,890880 to 3020800,1472512
#       : 62.578125,19.116211 to 64.819336,31.596680
63240003: 3020800,890880 to 3266560,1472512
#       : 64.819336,19.116211 to 70.092773,31.596680

Best regards,

	Marko