[Talk-ca] Coastline rendering problems, Richelieu River

[Pierre Béland]

There are also Coastline rendering problems on the Richelieu river around Saint-Jean-sur-Richelieu and Chambly.  The OSM history changesets list shows many Non-ct data remove and recreate operations in the area done by user PurpleMustang recently.

In Saint-Jean-sur-Richelieu, to correct the situation, I redrawed part of the riverbank who was simply deleted.

In Carignan, Ile Ste-Marie is still flooded.  There is no riverbank relation and I dont know if it has simply been deleted.

In Chambly, the river enlarges. There are two river that connect to the basin and island around extremity of these two rivers. There is a relation that was probably containing all the riverbanks roles (outer and inner).  But the relation 305614 only contains to inner roles representing two islands.

In south-east part of Chambly Basin, there is a point and islands on the east riverbank facing Fort de Chambly. The two islands included in the relation are rendered as lake and the water as land.
see http://www.openstreetmap.org/?lat=45.45798&lon=-73.26392&zoom=15&layers=M&relation=305614

Just
 on the right, there is the Huron river coming in. The polygon 
representing the part of the riverbank that join the Richelieu River is 
lost. And there is way waterway=river for this river. This means that 
the flow of water in the river is not indicated an no river name can be 
showed on the map.

http://www.openstreetmap.org/?lat=45.46277&lon=-73.25257&zoom=16&layers=M&relation=1775822

Part of the Huron riverbank joining into the Richelieu near the point as simply vanished.
see http://www.openstreetmap.org/?lat=45.45798&lon=-73.26392&zoom=15&layers=M&way=120716933

The riverbank around the basin is not included in the relation. This way is also improperly traced on the point facing Fort Chambly. It should be closer to the shore and not going around the tw islands.
see http://www.openstreetmap.org/?lat=45.45798&lon=-73.26392&zoom=15&layers=M&way=164251774

On this last image of the Basin, we see on top four islands for wich I cannot find the coastlines.Ile Goyer, Ile Demers, Ile-aux-Lièvres, Ile-aux-foins riverbanks have disappeared.North of these islands, the Riviere L'Acadie is joining Richelieu River.  The junction of the two rivers is improperly traced.  Polygons 24346195 (Riviere L'Acadie riverbank) and 164254015 (Riviere Richelieu) simply do not join.
http://www.openstreetmap.org/?lat=45.47204&lon=-73.2869&zoom=15&layers=M&relation=1775822
 
I have to conclude again that these rendering problems are caused by improper definition of coastlines and riverbanks.


In JOSM, we can see what the riverbank should look like using Geobase Imagery.
wms:http://ows.geobase.ca/wms/geobase_en?service=wms&request=GetMap&version=1.1.1&SRS=EPSG:4326&style=&format=image/png&transparent=true&layers=nhn:hydrography,nhn:network&WIDTH={width}&height={height}&BBOX={bbox}&



Pierre 
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