I'm trying to edit the area here https://www.openstreetmap.org/edit?editor=id#map=17/42.86431/22.57677 because the border between the heath and forest areas north of the boundary stone named Руй on the Bulgarian side of the border is wrong. The forest area appears to be connected to the Administrative Boundary, so I would like to disconnect it so I can expand the heath area. However, at the boundary stone, I can't disconnect because the point is part of a relation, while the other points on the administrative boundary can't be disconnected because "there aren't enough lines/areas to disconnect here" (i.e. the look connected but they aren't?). How to make this edit?

asked 04 Aug, 17:41

rhhsmits's gravatar image

accept rate: 0%

A quick warning first: This forest area is tagged as landuse=forest, this can include forests managed for things like paper production where areas may be clear-cut and re-seeded. Recently cut or seeded areas are generally considered to still be part of this kind of landuse.

Assuming that's not the case here:

This forest and heath are mapped as part of multipolygons. These are relations used to describe more complex areas made up of several different ways. In this case the border line was used as one of the outer ways of the forest multipolygon so the forest doesn't have dedicated geometry here.

A good description of how multipolygons work is here on the wiki.

This is quite a large edit for one session in iD. You are probably better off using something like JOSM. JOSM can view a way this long without dropping out of edit mode and has a relation window that displays relations in a better format (closer to the way they are described and stored).

If you use iD:

The easiest way to correct the forest geometry is probably to:

  • Add a node to the way shared by the heath and forest at the point where the forest breaks away from the existing line.
  • Split the way at this point.
  • If you now select the way to the left of the new split and scroll down on the left panel you will be able to delete the way from the forest relation (iD describes it a little backwards).
  • You can also now delete the border way from the forest relation.
  • Now draw a new way from the split you created to the other end of the border way following the edge of the forest
  • Add the new way to the (correct) forest relation using the + symbol under the relations heading in the left panel.
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answered 05 Aug, 00:10

InsertUser's gravatar image

accept rate: 21%

edited 05 Aug, 00:17


Editing relations like this is a good reason to avoid using iD. It's tricky enough doing it in JOSM, especially if you are new to relations. Using the Relation Toolbox inside JOSM makes these sorts of operations much easier but it still takes some practice.

My 2 cents

(05 Aug, 00:38) AlaskaDave

Thanks for your replies! I think I'll read a bit more about relations and JOSM, because I might mess up if I don't :) Here's a picture of the actual area that I took yesterday morning. https://commons.wikimedia.org/wiki/File:View_from_Ruj_summit.jpg

(05 Aug, 08:09) rhhsmits

The mapping in that area is a mess. Landuse=forest is not what I would choose for any of those wooded areas, rather use natural=wood. Then there are long ways of landuse=forest polygons that are adjacent but do not touch for some reason even though the "forest" is contiguous. When rendered by any software, this leaves a gap in the forest where none exists.

(05 Aug, 08:54) AlaskaDave

@AlaskaDave for some reason the heath multipolygon has a disconnected sections elsewhere and the holes in the forest are grouped together as a separate scrub relation. Unless they are closely associated or managed as a group most should probably be broken up into simple polygons. Some of the tags look a little odd too.

(05 Aug, 09:36) InsertUser

Indeed it looks like someone in the local municipality uploaded their own landuse data to OSM. They might be out of date: the area is getting depopulated and land that used to be grazed is getting overgrown and becomes scrub and then unmanaged forest.

(06 Aug, 18:46) rhhsmits
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question asked: 04 Aug, 17:41

question was seen: 183 times

last updated: 06 Aug, 18:46

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