[OSM-talk] Mapping huge lakes as coastline

[M∡rtin Koppenhoefer]

I wonder if it would not be better to map really big lakes as
coastline. This is done somewhere, e.g. here
http://www.openstreetmap.org/browse/relation/555716
(Baikal lake)

but it is not done here:
http://www.openstreetmap.org/browse/relation/1308279
(Lake Onega)

This results in bad rendering for low zoom tiles, with the lake
showing up on zoom6 but not on zoom5 (in Mapnik).

A few similar cases (quite big lakes modeled as water and not as
coastline) can be found all over the world, e.g.
- http://www.openstreetmap.org/browse/relation/1239458
(Vänern in Sweden, which by the way has a warning attached that
suggests it once was a coastline ;-) )

- http://www.openstreetmap.org/browse/relation/38997
(Lago de Nicaragua)

- some lakes in Canada, ...

Modelling these as multipolygons also might slower the rendering speed
the more complex the polygons get by adding further detail.

cheers,
Martin