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The banks of part of the Chao Phraya River flowing through Bangkok, Thailand are missing from the Mapnik rendering (http://www.openstreetmap.org/?lat=13.6671&lon=100.5497&zoom=13&layers=M ). Map tiles older than August still show the proper rendering and they seem fine in Osmarender. The ways/areas are tagged only with waterway=riverbank. What could be causing this?

asked 06 Sep '11, 18:47

Paul_012's gravatar image

accept rate: 33%

Try adding natural=water

(06 Sep '11, 23:47) LM_1

Try adding natural=water

natural=water is for lakes. It is incorrect to use it for river banks.

(07 Sep '11, 08:29) kolen

rivers are natural water bodies and this is even mentioned on riverbank wiki article http://wiki.openstreetmap.org/wiki/Tag:waterway%3Driverbank

(07 Sep '11, 10:16) LM_1

The reason why natural=water would usually not be used is that there is the specific riverbank tag for mapping riverbanks. Riverbanks do render without natural=water on them and the tag does convey more information then natural=water. So natural=water might not be strictly "incorrect" but it is unnecessary and not the usual way to do it.

(07 Sep '11, 11:43) dieterdreist

If you look carefully the way 23060205, you may notice that the polyline is self-intersecting in the right upper corner. Such geometry errors can disturb software applications trying to convert closed ways to polygons like osm2pgsql/Mapnik. Fix the self-intersecting way and problem should be solved.

Note that some quality assurance tools can report such errors.

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answered 07 Sep '11, 00:22

Pieren's gravatar image

accept rate: 15%

edited 07 Sep '11, 10:40

There are several broken multipolygon relations in that area, though I'm not sure if they would affect rendering of the river.

See for example Relation 1171990 and Relation 1171991. Both of these contain several ways which don't make closed areas, plus the parts with role inner are actually outside the polygon. Loading the area in JOSM and running the validator highlights these problems (plus more errors in that area).

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answered 07 Sep '11, 01:18

Vclaw's gravatar image

accept rate: 22%

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question asked: 06 Sep '11, 18:47

question was seen: 6,675 times

last updated: 07 Sep '11, 11:45

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