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So here is a managed forest area (which wasn't created by me, FYI). Technically, this isn't wrong as this whole area is owned by Boston Woods Trust and they've named it "Beech Wood". Only parts of it are actually managed forest though. It's built like a park, with exercising spots, benches and tables, etc.

Most importantly, it's got grassy areas, meadows, and some scrub/heath. However, I can't just map meadows on top of the wood, kind of like I tried on the right there. They just overlap and the tree icons are still displayed on top of the meadow, when there aren't actually trees there.

I'd really like it if there was a tag such as leisure=nature_reserve for areas like this. That way the whole area wouldn't just be represented as a wood, and you'd be able to map smaller areas within it, like you do with national parks and nature reserves.

What's the alternative? Should I map each separate wood area, and then merge the polygons and name it as "Beech Wood"? Should the meadow polygons also be merged since they're part of the park/wood/area? Or did I just make a needlessly long thread about what is clearly a nature reserve? Even though I've not seen it categorised as such anywhere?

asked 03 Oct '19, 09:53

AdventrrGrrl's gravatar image

accept rate: 0%

edited 03 Oct '19, 10:33

Hi, You need a multipolygon to hold the overall outer area (woods)and all the inner areas (grass) that are not woods. The meadow area you mapped is correct. Now have a look at making a multipolygon in the iD editor here :- If you need any help please just ask.

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answered 03 Oct '19, 15:21

BCNorwich's gravatar image

accept rate: 20%

Thank you! That page is pretty confusing. I've succeeded in making a multipolygon, although I'm still not sure what is meant by "contour".

Now I don't know how to add more areas to the multipolygon. I've mapped another grass area, but when I try to merge it the same way I did the first one, it seems like a new multipolygon is created as the whole wood gets a white overlay.

Edit 1: Oh, it seems for every inner relation you add, you need to add an outer one. Which confused me, because you'd think the multipolygon would "know" that the managed forest is the outer area/relation/contour/thing, so why would you need to re-enter it as the outer relation every time?

(03 Oct '19, 20:02) AdventrrGrrl

The updated mapping isn't bad, but note that using a multipolygon doesn't fully solve the problem. When you add inner rings to a multipolygon tagged name=Beech Wood, then what you're formally stating is that these are not part of the area called "Beech Wood". That's probably not true here, though.

An ideal modelling of the situation would require 1. a polygon for the area as a whole, carrying the name, and 2. smaller polygons for the patches of trees and grass. Unfortunately, there's no fitting tag for #1 yet (unlike for parks). Until someone invents one, the current solution is likely the best compromise.

(21 Oct '19, 20:22) Tordanik

Hi, I use the JOSM editor which is a lot easier for relations. I think in the iD editor a contour is a polygon (an area enclosed by a continous line). I think also you have to create all of the contours (areas) first, then tag only the outer area before selecting all contours and hit c in order to combine them into what is called a multipolygon. You should then be able to go back and tag the inner area as whatever (grass).

I've removed all the extra multipolygons, removed a duplicated area from your first multipolygon and all now looks OK.

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answered 03 Oct '19, 20:37

BCNorwich's gravatar image

accept rate: 20%

Ah, then I was doing it wrong. I thought "tagging" included adding new relations to the outer polygon, marking it as outer. Then, I'd merge it with the other polygons, which is probably why there were duplicate multipolygons.

So I tried doing it the way you described, testing it out on the Grange Wood, just south of it -

It seems fine, no duplicates or anything. At least I think!

What would happen if I extended inner areas up to the edge of the outer area? If you look at Grange Wood, the east edge is mostly wooded whilst the rest are grassy. What would you do in this case?

(06 Oct '19, 10:50) AdventrrGrrl

What I'd tend to do with areas such as this is add the whole area as a "landuse=forest" with the name on it and then add individual natural=wood areas within it for where the trees are (and also appropriate tagging for the non-tree areas). I've also suggested that "landuse=forestry" might work for this sort of thing (although perhaps not in this case) - but that is in no way a mainstream tag with similar usage to the other ways of tagging "places with trees".

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answered 05 Oct '19, 11:18

SomeoneElse's gravatar image

SomeoneElse ♦
accept rate: 16%


This looks to be broad-leaved woodland managed as a nature reserve. In general in the UK we map such places as natural=wood, leaving landuse=forest for commercial forestry plantations. The guidance on the OSM wiki more reflects usage elsewhere in Europe where forestry is often largely carried out in natural rather than planted woodland. I do second @SomeoneElse's suggestion of using landuse=forestry for the gamut of forestry operations (new plantings, recently felled areas etc), but I don't think it applies here.

(05 Oct '19, 21:12) SK53 ♦

I figure it's okay to leave it be as a managed forest. Making it a multipolygon is the best option, it seems.

Mapping edges that are grassy, by the way, can be done by adding inner polygons near the edge, but not exactly at the edge. As multipolygon is made and inner polygons are tagged as landuse=grass (or whatever else), you can drag those grass areas up to the edge of the outer polygon and it works fine.

Basically, solved. Thanks, everyone!

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answered 07 Oct '19, 11:07

AdventrrGrrl's gravatar image

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question asked: 03 Oct '19, 09:53

question was seen: 2,637 times

last updated: 21 Oct '19, 20:22

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum