On 17-11-2011 16:54, Michal Migurski wrote:
On Nov 17, 2011, at 6:46 AM, Frank Steggink wrote:
Quoting Michal Migurski<[email protected]>:
A cry of frustration:
I do bimonthly runs of the worldwide coastlines
(http://metro.teczno.com/#coastline), and Canada seems to be a recurring
source of problems. What the heck is going on up there? I consistently see new
imports of what seems to be Canvec data screwing up coastlines and making for
some deeply broken renders:
http://mike.teczno.com/img/broken-coast.png
Hi Michal,
The rendering error northeast of Quebec City was caused by a novice user who
has adjusted the Canvec data which was already there. The import in this region
was done by me about half a year ago.
The user in question had adjusted the coastline tags to waterway=riverbank, in
order for him to show it up properly on his GPS (while using mkgmap for the
conversion). He already became aware of what he has done, and has fixed the
error himself (which I think is laudable). I've done a check, and the coastline
looks all right to me. I'm not sure what to do with the remaining
waterway=riverbank tag. This is part of a larger discussion about what to do
with large waterbodies.
The slippy map doesn't show the corrected situation yet, because the coastline
shapefile is not updated very often.
I had noticed a lot of waterway=riverbank up there, you're right.
The first black and white image I link above is derived from the current,
November 10 planet dump, so it's a very recent picture of coastline errors.
Many of those errors didn't exist in the coastline I made from the November 3
planet dump.
Here are some sample locations in Canada where the checker has found errors:
http://www.openstreetmap.org/?lat=58.790035&lon=-94.202604&zoom=17&layers=M
http://www.openstreetmap.org/?lat=56.749700&lon=-92.698650&zoom=17&layers=M
http://www.openstreetmap.org/?lat=45.260826&lon=-66.086208&zoom=17&layers=M
http://www.openstreetmap.org/?lat=45.298267&lon=-66.117219&zoom=17&layers=M
http://www.openstreetmap.org/?lat=56.970073&lon=-92.627314&zoom=17&layers=M
http://www.openstreetmap.org/?lat=47.086208&lon=-70.745529&zoom=17&layers=M
http://www.openstreetmap.org/?lat=57.053591&lon=-92.000000&zoom=17&layers=M
http://www.openstreetmap.org/?lat=45.238757&lon=-66.055341&zoom=17&layers=M
http://www.openstreetmap.org/?lat=44.936914&lon=-74.704294&zoom=17&layers=M
-mike.
----------------------------------------------------------------
michal migurski- [email protected]
415.558.1610
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I've fixed some coastline issues at the Nelson River / Hayes River
mouths in the Hudson Bay, see [1]. There were some duplicated
coastlines, and an "inland" island (which was running the wrong way).
Near Churchill, MB [2] the coastline was already fixed by the Canvec
import user a few days ago. I didn't see any coastline mistakes there.
However, the treatment of "intermittent" water is far from perfect, and
not how I would have done it. I'd rather convert it to natural=wetland,
wetland = tidalflat, indicating that mudflats show up at low tide. Doing
this along the entire Canadian coastline, which is very extensive, is a
tough task. The coastline is really peculiar in some places, like here:
[3], so I'm afraid we haven't seen the last error. Tools assisting us in
error checks would be great, and absolutely necessary in the Canadian case.
Frank
[1] http://www.openstreetmap.org/browse/changeset/9856941
[2] http://osm.org/go/W6dBGeK-
[3] http://osm.org/go/W7CeaB
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