I want to add riverbank to a river, the Wang, that is a tributary to another river, the Ping. The Ping is a member of a large relation and has a defined riverbank already. How do I best construct the "junction" between the two riverbanks? The area of interest is included in the link below


Thanks for your help, as always

asked 30 Nov '13, 02:57

AlaskaDave's gravatar image

accept rate: 16%

Hmmm... Good answer. Thanks.

(30 Nov '13, 07:32) AlaskaDave

Thanks for the hint Andy.

I tried adding my new closed-way riverbank to the existing Ping River relation but it ended badly with open polygon errors aplenty. So I backed out and started again. I converted my closed-way riverbank to a multipolygon relation, then joined them as you would any other two relations. That is, I connected the two multipolgon riverbanks at top and bottom at the junction of the two rivers then deleted the way that was originally used to complete the Wang riverbank. I then made sure the Ping River relation AND the Wang River relation shared the small segment that now formed the interface between them.

Phew, It's a lot harder to explain in words than it is to do it.

Thanks again.

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answered 30 Nov '13, 08:56

AlaskaDave's gravatar image

accept rate: 16%

seen this? http://wiki.openstreetmap.org/wiki/Tag:waterway%3Driverbank#River_junctions added edit:- Dave. I just opened the editor again and i see that neither of the polygons seems to be complete, i'm sure they need to be.. they don't highlight as yellow all the way around when selected which they should. The way that forms the junction should be used as part of both riverbank polygons although the link suggests that this bit is not really a river bank, maybe someone can help us both on that point. I usually create long rivers by breaking the polygons into smaller ones that have common joining ways. like the one just mentioned. This works for me. Maybe that this will also be confirmed as ok.

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answered 30 Nov '13, 07:01

andy%20mackey's gravatar image

andy mackey
accept rate: 4%

edited 30 Nov '13, 19:43


@Andy: You were correct. Did you spot this in Potlatch, or iD? (JOSM doesn't highlight in yellow.)

They both looked alright in JOSM and the OSM slippy map but I had forgotten to add the shared segment into my new Wang River multipolygon. I added it as "outer" to that relation, double checked to see it was included in the Ping River relation and now assume everything is kosher.

Good call Andy.

(01 Dec '13, 00:31) AlaskaDave

I used Potlatch2

(01 Dec '13, 07:37) andy mackey

Dave and anyone else. I have just found that Potlach2 does not highlight the whole polygon if it is part of a multipolygon, I wrongly thought that the total highlight or lack of it showed a broken one. I see that the rivers render fine now. you live and learn.

(02 Dec '13, 07:40) andy mackey
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question asked: 30 Nov '13, 02:57

question was seen: 3,089 times

last updated: 02 Dec '13, 07:40

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