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Fixing broken riverbanks

於 2017年二月24日 由 PlaneMad 以English發表。

Stumbled upon a dried up Nile on the map, which seems to be a jumble of large multipolygons.

This might require the expertise of an expert with the JOSM relation editor which can be a time consuming process.

It would be great if someone could make a simple howto tutorial for fixing such scenarios to help fix so many other big rivers that are broken this way.

位置： Ad Douiem, White Nile, Sudan
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討論

由 imagico 於 2017年02月24日 15時17分 發表的評論

There is no universal recipe to fix this kind of problem. There are many different kinds of mistakes that occur in broken multipolygons and each of them requires a different approach.

Things that are helpful usually with with riverbank polygons:

  • make the individual polygons small - don’t make the mistake of fixing things by merging everything into one big polygon.
  • decide on which area your polygon is meant to cover along the river
  • throw out all members outside this area
  • throw out duplicate members (which are in the relation several times)
  • assemble a closed outer ring, if necessary drawing new ways or splitting ways
  • add all islands within as inner rings
  • make sure all tags are on the relation and none are left on the member ways (unless they apply only to them)
  • create additional polygons using members previously removed as necessary

This is all a matter of exercise and training but even with a lot of experience this is still tedious work.

由 mustafakamil 於 2017年03月 2日 05時12分 發表的評論

I’m from Sudan, I am having the same problem in riverbanks of the Nile because the Nile in flood season comes out of the main stream

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