[Talk-ca] Définition de zones fluviale / cotières vs chenaux de navigation ou baies

[Pierre Béland]

Indian Arm est effectivement un exemple où ses contours sont aussi définis dans Burrard Inlet et Osmose ne rapporte pas de problème.
Indian Arm (8330415) https://www.openstreetmap.org/relation/8330415Burrard Inlet (8330512) https://www.openstreetmap.org/relation/8330512#map=11/49.3520/-122.7077 Je vais poursuivre la révision pour remettre les contours extérieurs des Estuaires comme ils étaient auparavant.

Pierre 
 

    Le vendredi 11 mars 2022, 16 h 23 min 14 s UTC−5, David E. Nelson via Talk-ca <talk-ca at openstreetmap.org> a écrit :  
 
 Hence another reason for me using "one point, one name".  It would forestall data quality assurance tools such as Osmosis from throwing such errors.
I do not know if we have any existing explicit examples of such a hierarchy, but as a couple of implicit examples, you have the Saguenay Fiord as a child of the St. Lawrence River Estuary in Quebec, and you have the Indian Arm as a child of the Burrard Inlet in British Columbia, which itself is a child of the Strait of Georgia.  And I do not particularly believe that you can be in both Burrard Inlet and the Strait of Georgia at the same time.
Perhaps relations with type "boundary" should be used to refer to bodies of seawater that have at least one child, as the role "subarea" is valid for boundary relations, while "multipolygon" relations are used for the lowest level bodies of seawater, those with no children at all.
- David E. Nelson

On Mar. 11, 2022 11:55, Pierre Béland <pierzenh at yahoo.fr> wrote:

 Le jeudi 10 mars 2022, 18 h 04 min 15 s UTC−5, David E. Nelson via Talk-ca <talk-ca at openstreetmap.org> a écrit :  

A simple parent-child approach can be used to associate side bays with larger straits, gulfs or seas, either explicitly by adding the side bays to the larger bodies as child relations, or implicitly by observing that if that you can only enter a small bay from the open ocean by boat by passing through a larger seawater body, such as a sea, strait or gulf, then that small bay is a child of the larger seawater body. 

Si nous retracons les estuaires comme ils étaient originalement en suivant les contours de la rive, nous aurons :1. premier niveau hiérarchique avec relation-polygone correspondant à l'estuaire2. des relations-polygones qui définissent chenaux et baies (natural=[bay|strait]).
Avec une telle définition, les polygones vont se superposer et il est possible que les outils de qualité tels que Osmose vont indiquer comme erreur cette superposition des polygones ce qui amenera des contributeurs à venir constamment réviser ces infos.
A-t-on des exemples existants de telle hiérarchie des différents polygones estuaire, baie, etc ?
Pierre 
 

    Le jeudi 10 mars 2022, 18 h 04 min 15 s UTC−5, David E. Nelson via Talk-ca <talk-ca at openstreetmap.org> a écrit :  
 
 There wasn't a consensus that my method was unacceptable either, which left me with no such guidance on this.  If I was to rewind time and do this over again, I probably would have reached out to the community first, perhaps even put a project page on the wiki, and reached out for such guidance.  But obviously, as you can see, I leapt before I looked.  Such is the benefit of hindsight.
There are two very simple reasons I used a "one point, one name" system for mapping bodies of seawater.  First, I wanted to minimize my own interference with editors wanting to work on the coastline.  If they choose to edit the coastline, perhaps splitting or joining parts of it, without downloading any relations first, it would minimize the time I would have needed to subsequently fix up the seawater relations, as as few of the seawater relations would have ended up broken.  Second, it is a "divide and conquer" approach, meant to divide the coastline into logical parts so that as few member ways as possible would need to be used to form each of the seawater areas.  A simple parent-child approach can be used to associate side bays with larger straits, gulfs or seas, either explicitly by adding the side bays to the larger bodies as child relations, or implicitly by observing that if that you can only enter a small bay from the open ocean by boat by passing through a larger seawater body, such as a sea, strait or gulf, then that small bay is a child of the larger seawater body.  I did not mean at all for this scheme to imply any false shapes for seawater bodies.
- David E. Nelson  

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