Hi everyone!

For context, I am talking about the island called "Stora Jolpan" found here: https://www.openstreetmap.org/#map=15/59.4781/18.8179

On the regular rendering, the island is not covered with forest, however the little island "Lilla Jolpan" below is. The larger island is, however, a multipolygon that is tagged with landuse=forest. So why does it not get rendered?

Why I am asking: I did not map this, but I was about to add the forest to this island when I discovered that someone had already added it. Now I don't know how to fix the fact it's not rendering...

Thanks a lot!

asked 21 Aug '19, 09:25

novabeat's gravatar image

accept rate: 0%


I've redrawn the forest areas separate from the coastline, removed the coastline multipolygon, created two new multipolygons. I think when re-rendered it will be OK, I'll look again later.

The island is rather crudely drawn, needs a bit of time and patience to tweak it.

(07 Sep '19, 12:54) BCNorwich

@BCNorwich can you maybe link to the changeset? I'd like to see what you did so I can learn from it

(08 Sep '19, 08:09) novabeat

Hi, It was Changeset: 74203875

(08 Sep '19, 09:56) BCNorwich

The multipolygon defining the forest (relation 9678248) seems to be broken. I cannot check in detail now but by just looking at it I see that for example the wetland between Stora and Lilla Jolpan is supposed to be an inner within the outer Stora Jolpan way. But in fact both intersect.

I would try to clean up the multipolygon so that it only has true inners. One of the quality tools out there might find more problems with the relation.

The mentioned wetland is half floating on the ocean. I guess that needs to be mapped differently anyway.

permanent link

answered 21 Aug '19, 10:01

TZorn's gravatar image

accept rate: 14%

edited 21 Aug '19, 10:02

thanks for the advice. I am not feeling very comfortable with relations. Do you have some tips on how to learn about how to fix that?

(01 Sep '19, 09:54) novabeat

I see you are already using JOSM. You should stick to that editor when editing relations. There are a couple of guides out there that can assist you. Check them out and come back here if you get stuck somewhere.


(02 Sep '19, 08:45) TZorn

Awesome! Thanks for the links and the advice!

(08 Sep '19, 08:09) novabeat

That looks like a bit of a mess.


Tip: Any 'inner' which touches an 'outer' shouldn't be part of the MP relation. So all wetlands & beaches plus a couple of grassed areas which reach to the coast. They should be mapped as ways so remove the inner relation ref. The 'outer' should be drawn around them.

permanent link

answered 22 Aug '19, 13:50

DaveF's gravatar image

accept rate: 9%

thanks for the advice. I am not feeling very comfortable with relations. Do you have some tips on how to learn about how to fix that?

(01 Sep '19, 09:55) novabeat
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question asked: 21 Aug '19, 09:25

question was seen: 761 times

last updated: 08 Sep '19, 09:56

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