Some water bodies & shorelines are not rendered at all

[Matthew Marsh]

There are some major water bodies which are present in the OSM database, but which do not render in OsmAnd.

One example: In Lake Ontario / St. Lawrence River near co-ordinates 44.2453, -76.3819, the entire river, lake and shoreline is present in the OSM database and displays correctly in browser-based views. When viewed in OsmAnd, all of Lake Ontario south of this point is rendered as light gray (land) with no shoreline.

It appears as if the shoreline might be represented by a series of open path/polyline objects, rather than as closed polygons covering the water - perhaps OsmAnd is unable to determine which side of the shoreline the water should be on?

[Max Erickson]

Traditionally the Great Lakes have been represented using natural=coastline (which OSMAnd interprets as having water on the right). Someone decided that was not correct and changed Lake Ontario:

https://www.openstreetmap.org/changeset/24692392

I haven't checked that this is the problem, but it could be related. Because it's OpenStreetMap, we also have another user removing natural=water from the Lake Michigan relation:

https://www.openstreetmap.org/changeset/27063265

Of course, these look to be Europeans pursuing (different versions of) correctness without bothering to ask anybody on talk-us what they think.


Max

[t.]

Besides this, or in addition to, there is another issue for water bodies formed as multi-polygons spanning different political entities.

For the US, as well as for Germany, the maps are split into Federal States. These map files are generated from the OSM-extracts produced by Geofabrik. It is a well known issue there that large multi-polygons at the boundary of these extracts (which are slightly larger than the state it covers) can be incomplete. 

See the discussion here: https://groups.google.com/forum/#!topic/osmand/1f337Gc-GIk

[Aceman444]

The Great lakes are noticeably missing also on the default "World map" so there should be no problem caused by OsmAnd splitting political areas into different files. Only Canadian part of Lake Superior is visible. So either OsmAnd is rendering something wrongly or the lakes are split on country boundaries and using different tags on ways on each side of the boundary and just collected into an inconsistently tagged multipolygon or something like that.
The World map is dated 30th of July 2014 so it shouldn't be a recent "vandalism" or tagging fight. Or is the dispute going on for months?

[Matthew Marsh]

All of that sounds plausible. There does appear to be something funny in the way polygons are closed (or not closed) in some areas, 44.2453, -76.3819 for example. It's pretty clear when you load the in-browser editor from openstreetmap.org that the shoreline representation is inconsistent from segment to segment.
What confuses me, though, is that other OSM viewers - notably, the openstreetmap.org in-browser viewer - nevertheless parse the Great Lakes shorelines correctly. It's only in OsmAnd that the shorelines fail to render at all.

[t.]

As said before, OsmAnd data are generated from individual files per federal state, thus, even if they overlap, large relations can be broken.

The OSM slippy map is rendered from a database that contains the whole planet file, thus no broken relations on file boundaries. 

[Fabien Nicollet]

Hello,

The issue with the Ontario lake is still present in the recent OsmAnd data files, the map is rendered either with the map being filled with water or with land. 

Is there a way to fix this issue or a workaround? Should the data be edited in OSM to get the proper tags?

Thanks,

Fabien