Coastline Eemscentrale not connected

Help and support
1

When using osmcoastline on a map in the area of Eemhaven, there is an error message that reads

“Closing ring between node 2730742930 and node 48484912” I have captured this note

https://www.openstreetmap.org/note/5219939#map=14/53.43725/6.89426&layers=N

because I was not sure how to fix it. Looking at the osmcoastline output for the map in the proximity of Niedersachsen, there are a few of these messages. The broken map causes rendering problems with navigation software as discussed here: How to stop the flooding? · Issue #1399 · navit-gps/navit · GitHub

It would be great if we could fix it somehow. Being new I am unsure of the procedure and was sent here when asking in openstreetmap@conference.macaw.me

I have searched but so far it is not even clear where between those two nodes the actual problem exists.

2

The coastline is fine, as you can see here: OSM Inspector | Geofabrik Tools

The problem most likely stems from you using an in-exact extract of the OSM data that somehow cuts of some data here. I suggest you either just download the coastline data from https://osmdata.openstreetmap.de/ or use a larger OSM extract and cut the coastline to the needed area after processing. That way you don’t get weird problems around the boundaries.

3

This problem was likely caused by parts of the Netherlands coastline being included in Geofabrik’s Niedersachsen export, and that has been repaired in avoid including Dutch coastline in Niedersachsen file · geofabrik/polygons_download.geofabrik.de@a85bad4 · GitHub - however, due to the fact that multipolygon relations are completed when Geofabrik build their extracts, something like this can always happen - imagine a large multipolygon that has among its members some coastline bits in Germany and some in the Netherlands, but not the complete coastline. This would lead to a patchy Netherlands coastline being included in the Germany (or Niedersachsen) extract.

4

Haha, then we can all have the conversation here :slight_smile:

I do appreciate the help a lot, thank you very much. By both of you, @Jochen_Topf and @woodpeck

I attempted to do another osmium extract using the very same poygon cutout. Unfortunately that did not yet help as there are still artefacts. If I remove the coastline entirely, then the map looks ok except at the coast, which is an improvement except when I need these areas at the coast.

osmcoastline seems to be able to close the open rings, and write its output to a spatial database but I cannot get it to output a pbf file, nor have I found another tool that could convert the spatial db to pbf. I tried

spatialite_osm_filter -d test -o test.osm -w wk
SQLite version: 3.46.1
SpatiaLite version: 5.1.0

DB ‘test’
doesn’t seems to contain valid OSM-RAW data …

for this content of the file wk:

POLYGON((6.295165 51.293485, 6.295165 54.239552, 11.607313 54.239552, 11.607313 51.293485))

The goal of this is to process a pbf file that may contain coastline-debris from adjacent map areas and fix it with osmcoastline before using the result in a navigation tool.

5

That’s not something you can do with osmcoastline.