Hi, I’m trying to map a school, and I marked the school grounds with landuse=education, but the school grounds are fenced, do I add a barrier=fence tag to the same closed way that has the landuse=education tag or what should I do?
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Adding barrier=fence around the school way seems reasonable to me.
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no, you absolutely shouldn’t add barrier=fence to the object that represents the school, it would be conflating the fence and the school.
There are several alternative options how to handle it:
- add fenced=yes to the school (note it is a property, not a feature tag, and also note that it is marked as deprecated and will not be rendered by most maps)
- create a multipolygon for the school (create a relation, add the way to it with the role “outer” and move the school tags from the way to the relation), then add barrier=fence to the way.
- draw another way over the way representing the school, reusing the nodes, and add barrier=fence to it.
While option 2 may sound complicated at first, it actually just takes 2 steps in JOSM: select the school, hit ctrl+b to convert to a multipolygon and move the tags all in one go, then alt+a to add the barrier tag to the way.
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Adding barrier=fence to the landuse may be an ok shortcut to get some quick results, but it’s cleaner to map the fence as a second way:
- It makes it clear whether any additional tags describe the fence or the fenced area.
- It avoids duplicate fences between two adjacent properties.
- It allows the fence to be split when necessary, e.g. to add different tags to different sections of the fence.
The fastest approach to add the second way depends on your editor. Most offer some kind of “follow way” feature which makes this pretty quick. JOSM power users may want to consider the shrinkwrap plugin.
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Well, that’s a fency schema… 
(sorry for the joke)
for 2, I would add barrier=fence to the same way that has the landuse tag, IN the multipolygon? Sorry, being new to OSM mapping I still don’t 100% understand multipolygons.
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yes, there would be a way that
- has
barrier=fencetag - has
outerrole in multipolygon, multipolygon is tagged as a school
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Nothing multi about that polygon.
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they meant Relation:multipolygon - OpenStreetMap Wiki that can also be used for cases where there is single outer member.
It can be useful in cases where way itself would get different tagging
Not very surprising, @dieterdreist was the user adding that use case to the wiki page. In my opinion it is not a valid use for that relation type.
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In this way, how would I select the fence instead of the landuse then? if they both share nodes, there’s no easy way to even know the way with the barrier is under the way with the landuse tag, right?
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in my opinion it is a valid use and superior to multiple ways sharing the same nodes
Look at the Tenniscourt here as sample. Point your mouse directly to the way representing the fence and you can mark the fence. Point the mouse into the green stripe within the fenced area und you can mark the tennis court.
This represents the option 3. proposed by @dieterdreist
This is a quite simple solution if you are not yet used to relations.
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Well, a multipolygon is defined as a combination of multiple polygons for cases where complex structures can’t be accurately mapped with a simple polygon. This is not the case here.
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Not really. Multipolygon is defined as having 1 or more polygons forming it. Multipolygons with single outer member are still valid, though in some cases the same can be expressed by tagging it directly on outer way (but not in this case)
I usually use the parallel copy tool in JOSM to drag the landuse 20 cm inwards and make that the fence. The fence can than be edited much more realisticly.
Example with hedges.
Landuse and barrier on the same polygon is not the right way in my opinion.
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That seems appealingly simple. But it is described as deprecated in the wiki. I know the wiki does not always provide definitive answers, but it does suggest that using this tag may not achieve what the mapper wants.
https://wiki.openstreetmap.org/wiki/Key:fenced
That seems appealingly simple. But it is described as deprecated in the wiki. I know the wiki does not always provide definitive answers, but it does suggest that using this tag may not achieve what the mapper wants.
Key:fenced - OpenStreetMap Wiki
yes, it would have a good chance of being missed, generally usage is dropping for the tag: http://taghistory.raifer.tech/#***/fenced/ so if you want the information to be shown on maps, barrier=fence is much more likely to be used.
I only mentioned it for completeness, and because it illustrates the difference of a property and a feature tag
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In my opinion, this is more indirection than necessary. While it’s great that folks here are taking the time to explain multipolygon semantics, the fact is that new mappers often make their first edits around schools, parks, and playgrounds. Creative uses of relations are likely to confuse these mappers, who are more likely to make a mess of them.
Moreover, considering the schoolground to be coextensive with the fence is often just a crude approximation. If you come back later and realize there’s an opening in the fence or part of the schoolground lies outside it, then you have to perform surgery on the fence, and the multipolygon turns out to be counterproductive.
This is the most conceptually straightforward representation (apart from fenced=yes). Some mappers dislike this approach because coincident ways are more difficult to select in JOSM. In iD, you can select the schoolground area by clicking on its translucent partial fill, and you can select the fence by clicking on the outer edge. In JOSM, you have to double-click the interior of the schoolground area to select it and Alt+click (Option-click) the outer edge a couple times to select the fence.
Even so, I think this is a weak reason to disfavor using coincident ways in this case, since it’s otherwise more maintainable. For example, if you ever need to differentiate between the schoolground’s and fence’s geometries in the future, both editors let you detach the two features using a single keystroke.
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| Minh_Nguyen Minh Nguyễn
November 21 |
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dieterdreist:
create a multipolygon for the school (create a relation, add the way to it with the role “outer” and move the school tags from the way to the relation), then add barrier=fence to the way.
In my opinion, this is more indirection than necessary. While it’s great that folks here are taking the time to explain multipolygon semantics, the fact is that new mappers often make their first edits around schools, parks, and playgrounds. Creative uses of relations are likely to confuse these mappers, who are more likely to make a mess of them.
Moreover, considering the schoolground to be coextensive with the fence is often just a crude approximation. If you come back later and realize there’s an opening in the fence or part of the schoolground lies outside it, then you have to perform surgery on the fence, and the multipolygon turns out to be counterproductive.
I don’t experience this. With iD you do not even notice it is a multipolygon, you only see a school and a fence. If you have to add more details on the fence, you can add nodes to it and split the way. All the editors I am using will keep (add) the way parts in the multipolygon-relation automatically. On the other hand, with overlapping ways, the problems start (which way do you want to split, and into which do you want to add the nodes, etc.)
draw another way over the way representing the school, reusing the nodes, and add barrier=fence to it.
This is the most conceptually straightforward representation (apart from
fenced=yes). Some mappers dislike this approach because coincident ways are more difficult to select in JOSM. In iD, you can click the schoolground area’s translucent partial fill to select it without fussing with the fence line. However, to my knowledge, this is not possible in JOSM even with the iD map paint style enabled. The closest thing is the Ctrl+middle click gesture (Cmd+middle click on macOS) to show a menu of overlapping ways.
Even so, I think this is a weak reason to disfavor using coincident ways in this case, since it’s otherwise more maintainable. For example, if you ever need to differentiate between the schoolground’s and fence’s geometries in the future, both editors let you detach the two features using a single keystroke.
with the multipolygon approach, you simply draw the new geometry you like and remove the tag from the part of the outer way (select 2 nodes and split if required). No need to select and detach (potentially many) nodes. If the geometry is different, you also may not want to use the same amount of nodes for both, so after detaching you will also potentially have to delete nodes you do not need if you are going to develop the new geometry by transforming the other.