mapping holes in an area


In my local area I have a lake with an island in the middle and this is causing me a couple of problems.

Firstly I read the wiki:

Now it might just be because i’m dyslexic, but that to me isn’t even English.

Can someone explain this concept a little more clearly? (images would help me, if you have the time!)

Also second issue, I know if it’s an island I need to use “natural=land” but it’s also got allot of trees on it, so ideally i would like to do “natural=wood”… can i do both? I read somewhere that you can double up by doing “natural=land;wood” does that work and render well? or should i just do “natural=wood”? or maybe two layers?

Thanks for any help you can give me!

  • Daniel

It isn’t particularly clear but I think what it is saying is to create a ‘polo’ shaped object, make a ‘C’ shape, where you go around one way, then go inwards and back around the other way to mark the inside. Then to make it a ‘polo’ make the 2 sections of the ‘C’ where you turn around so close that they use the same nodes.

By psuedo edge I think it’s referring to the wood itself, rather than a pseudo edge for the osm-data, which is rather confusing.

For lakes though I thought just drawing an island with natural:land; layer:1 would work

2nd Question:

Natural:land;wood won’t render, and seems a messy way to go. You should either just make the island just natural:wood, or make a wood on the island (separate way) tagged natural:wood again, or make 2 ways on the same circle, one tagged natural:wood, the other tagged natural:land

A diagram

A. 2 ways…
B. A C shaped wood
C. Shift the edges of the C shape together

Excellent, thanks for your help! much clearer now.

I’ve changed the description on the wiki page you linked to. Please check it and edit it if you feel it still makes little sense from your perspective.

Then there’s this Relations/Multipolygon concept which seems to be tackling the same problem, but I’m not sure if any renderers look at that data yet.

@Harry Wood.

I think they do, there are some beautiful multipolygon houses in Helsinki.