[Talk-ca] Building Import update

Sun Feb 3 19:09:30 UTC 2019

 Le «acid test» de John, avec une architecture aussi irrégulière, a abimé les «Bay Windows» et l'eau fuit de partout tout comme son analyse basée sur Orléans à l'extérieur de la zone étudiée ! Une analyse plus approfondie de la zone du centre-ville nous montre qu'il y a peu de telles architectures. Cette réponse ne tient pas la route et n'explique pas le ratio élevé de polygones avec formes irrégulières dans la base OSM.

Le feedback de Nate pour Toronto montre qu'il a a beaucoup de données à corriger pour orthognaliser. voir https://lists.openstreetmap.org/pipermail/talk-ca/2019-February/009080.html

Ce que je comprends bien aux réactions de John depuis le début, c'est laissons les données telles qu'elles.  Plusieurs évitent de se pronconcer. Cela ne me convainct pas de l'urgence pour un petit groupe de se hâter à importer les données sans tenir compte de problèmes de qualité importants.

J'ai révisé mon script qualité pour cerner davantage les formes régulières. Il tenait compte jusqu'ici des angles à 90 degrés et des autres formes régulières (hexagones, octogones, etc). Je l'ai révisé au cours des derniers jours acceptant une tolérance jusqu'à 5 degrés. Les angles à 45 degrés  (ie. 45, 135, 225, 315) sont maintenant pris en compte. 

Ces modifications ont eu peu d'impact sur le nombre de bâtiments identifiés avec formes irrégulières. Cela confirme qu'il a a des polygones avec formes qui s'éloignent sensiblement de formes régulières.

Avec une tolérance de 3 à 5 degrés, on constate que 17% des bâtiments peuvent être orthogonalisés automatiquement à l’aide de scripts. Ou encore il serait possible de réviser tous les bâtiments avec tolérance de 1 à 5 degrés (ceux à moins de 1 degrés resteraient tels quels. Malgré tout, Il reste toujours 25% des bâtiments qui doivent être analysés manuellement et voir si des corrections sont nécessaires.

 Pierre 

    Le jeudi 31 janvier 2019 20 h 48 min 03 s HNE, john whelan <jwhelan0112 at gmail.com> a écrit :  

 I can't think of a way to pull in all the suspect buildings but if you have a look here:
https://www.openstreetmap.org/search?query=k4a%201m7%20canada#map=19/45.47095/-75.48696

556, 558, 560 are all examples that I think would fail your test.  However they are the shape of the buildings.
As far as I am aware we haven't had any outraged users complaining about the building shapes in Ottawa and that I think is the acid test.  The Ottawa building import has been useful certainly in gaining new mappers and adding tags to the outlines.
Your test originally was to pick out very badly mapped buildings that had been done in iD and I would agree with you that some were very bad.  Sometimes 3 or 4 times the size of the building and some very odd shapes indeed.  From memory most were done on HOT tasks with the iD editor.
These I think we should definitely aim to avoid but where the representation of the building is reasonably accurate then I think they are acceptable.  We are using reasonably experienced mappers who would balk at importing some of the stuff we saw in Nepal etc and rightly so.  They'd almost certainly be very vocal about the quality of the data.
There is a case to be made that most residential buildings would be acceptable if they were mapped with the JOSM buildings_tool plugin and all the small blobs take up database size.  There is also a case that you get a better sense of the building with the small blobs, bay windows etc.  I don't have strong feelings either way but I strongly suspect there are examples of both already in OSM in Canada.
I note that both Google and Bing have most buildings these days and it has almost become a map user expectation.  Certainly there are apps that guide blind people that use the building outlines in OSM.  There is a case that says to keep up with the competitors we really ought to have buildings.
I think someone else has commented that parts of the Microsoft building outline from scanned images in the US is problematic.
So given the results in Ottawa are comparable to Ontario and in my opinion Ottawa is acceptable then I think the rest is also acceptable.  Certainly Kingston where not all building angles were right angles weren't noticeable to me by eye or perhaps my eyesight is just getting worse with age.
Cheerio John

On Thu, 31 Jan 2019 at 19:51, Pierre Béland <pierzenh at yahoo.fr> wrote:

Salut John,
Voici les résultats d'analyse de géométrie des bâtiments pour Ottawa centre-ville.bbox : 45.4224,-75.6994,45.4568,-75.6122
-  20,372 Bâtiments
-      173 Bâtiments avec superposition  (0.1%)
-   11,534 Bâtiments avec formes irrégulières  (56.6%)

Nous avons donc un résultat semblable aux imports en Ontario que j'ai analysé il y quelques jours. A mon avis, en haut de 5%, il faut regarder de plus près et expliquer pourquoi autant de formes irrégulières.

J'ai créé des Requêtes overpass pour extraire les bâtiments identifiés dans l'analyse. Télécharger les requêtes à partir des fichiers ci-joints. 

Pierre 

173 Batiments avec superposition
Req Overpass voirhttps://www.dropbox.com/s/fp1cimouhhfbm9s/on_Ottawa_centre_2019-01-31_batiments_superposes_OSM_req_Overpass.txt?dl=0

11,534 Bâtiments avec formes irrégulières  (56.6%)
Req Overpass voir https://www.dropbox.com/s/c68nb9dbudtp679/on_Ottawa_centre_2019-01-31_batiments_irreg_OSM_req_Overpass.txt?dl=0

-------------------------------------------------------------------------------------

    Le lundi 28 janvier 2019 09 h 17 min 37 s HNE, john whelan <jwhelan0112 at gmail.com> a écrit :  

 Interesting, although I'm not sure what the best approach is.  
31 Hamilton is interesting.  If you look at the buildings next to it they don't have house numbers.  Look at the history and you'll see it was first created in 2010 with potlatch and edited once more in 2011.
At my first glance at Kingston the small deviations form 90 degrees did not stand out. 
I think we can reasonably expect Microsoft to create a Canadian buildings file and you seem to be comfortable that the ones it has in the US are of a reasonable standard.
Part of my background is large databases and my personal view is the minimum data needed the faster the system runs and less data needs to get flipped round and backed up.
Could you run the analysis over Ottawa?
Looking closely at a few in Ottawa I note that there are some bay windows and other small features I might not have bothered with if mapping with JOSM with the buildings_tool. Because of a few 45 degree angles involved this isn't something that can be easily solved.
Ottawa I think at some level can be considered a reasonable success.  Certainly we added a lot of extra information to the building outlines.
I think the trade off is using the municipal data gives us the buildings with perhaps more detail than I might like but many would like to see the buildings imported.
Dunno (Do not know for translate tools.)
What is the ideal building outline in OpenStreetMap?
What is an acceptable building outline in OpenStreetMap?  

Suggestions
Thanks
Cheerio John

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-ca/attachments/20190203/b6af1c47/attachment-0001.html>