[OSM-talk] Waterway rel with mix of line & poly

Dave F davefoxfac63 at btinternet.com
Fri Sep 21 12:33:07 UTC 2018



On 21/09/2018 00:31, Warin wrote:
> On 21/09/18 06:11, Jem wrote:
>> Thank you both. That's very helpful.
>>
>> On Thu, 20 Sep 2018 at 22:25, Dave F <davefoxfac63 at btinternet.com 
>> <mailto:davefoxfac63 at btinternet.com>> wrote:
>>
>>     Hi
>>
>>     Short answer: Yes
>>
>>     There's a few problems here:
>>
>>     Relations should not be used to collect thing together.
>>
> ? That is what they can be used for. See the site relation as an example.

This reinforces my point. Site is repeatedly used to form unnecessary 
collections of things (such as braces of bus stops, one on each side of 
the road which already share the same name: 
https://www.openstreetmap.org/relation/2726555)

...or by people who are unaware OSM is geospatially aware. Note the 
'site' example given on the wiki: "Relation to group elements of a site 
such as a school together.". If the school has a amenity=school polygon 
boundary, which it should, everything within it is a part of that school.

It wouldn't be so bad if people didn't give up half way through creating 
them.

>>     There shouldn't be tags on the ways which conflict with those in
>>     the relations
>>
> True.
>>
>>     MP relations require a 'type' tags and 'inners' & 'outers' roles
>>
> True
>>
>>     In this case the Southern section shouldn't be a polygon
>>
> Did not look.

Clarification: It shouldn't be a part of the multipolgon relation. It 
should still be a polygon.

>>     MP relations should be restricted to the areas which have inners:
>>     https://www.openstreetmap.org/relation/2571440#map=19/51.15275/-2.05045
>>
> No. They can be used to collect a series of outer ways to form the 
> boundary of a feature e.g. an administration boundary usually shares 
> ways with adjacent administrations.

Clarification: I was referring to specific examples of river MP's to 
include islets. It makes it much easier to maintain if the relations are 
kept as small as possible around any inners. If the MPs are large, some 
contributors mistake them as untagged ways and add duplicating tags to 
them. To help avoid this confusion I add a note tag to the way: 
https://www.openstreetmap.org/way/431275464

Cheers
DaveF
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