[OSM-newbies] Coastline

[Rob Reid]

Douglas Luery wrote the following on 30/01/2008 03:47:
>
> I was hoping Eric Brelsford request for help (7^th Jan 08) in creating 
> "coastline" would have resulted in help/hints – unfortunately I did 
> not see any.
>
> I have, after a fair amount of struggling, managed to complete the 
> coastline of Antigua in the Eastern Caribbean (Shown on the world map 
> by the capital "St. Johns")
>
> Only to find after a couple of weeks that when viewed in Osmarender, 
> two significantly large portions of the coastline have disappeared - 
> it appears that two large tiles, on the once coastline, have become 
> designated as land, with land now going miles out to sea, - completely 
> messing up the mapping of Antigua .
>
> I am at a loss how to correct this as the affected areas are one 
> complete "way" of coastline passing into and out of the two erring 
> tiles but show correctly in the neighboring tiles.
>
> Help!
>
> Douglas Luery
>
>
> 	
> 	
>
Douglas, I'm running a re-render of your affected tiles now and they 
look fine here. I will upload when they are complete. I suspect what may 
have happened is that your troublesome tiles were affected by the bug in 
Osmarender detailed here : 
http://lists.openstreetmap.org/pipermail/tilesathome/2008-January/001779.html

Even though your tiles should now be OK the following info may be of use 
to you.

One useful resource for coastlines is the Coast Line Error checker 
<http://wiki.openstreetmap.org/index.php/Coastline_error_checker>.

In the case of Antigua it is picking up a couple of errors.
http://tile.openstreetmap.nl/coastlines.html?zoom=9&lat=17.13504&lon=-61.81458&layers=B00T
Note that in your case it is a bit hard to tell where the errors are due 
it not showing outline of the main island (I suspect this may be due any 
recent coastline changes you have made and the outline should appear in 
the next update or so).

As you stated the coastline of the main island appears to be ok but I 
can see a couple of problems on some of the smaller islands. I'll detail 
them here but won't fix them so that you get a chance to see them unless 
someone else gets there first.
- On the west cost there is 4 small islands here 
http://www.openstreetmap.org/edit.html?lat=17.08006&lon=-61.90957&zoom=16
- counting from the left the 2nd and 4th island are tagged with 
key=coastline rather then natural=coastline
- the 3rd island has a small extra piece of coastline sticking out from 
the bottom.

Ok, I'll stop listing them as it looks like someone else is fixing the 
others I saw.

Cheers

rcr