Hi, >From my understanding, natural=coastline is just a way to map large water >areas.
- The advantage of using this tag is that it can be composed by multiple ways without the need of a relation type=multipolygon or doesn't need that all ways be joined togeter to get a single closed way. - The problem using this tag is that processing is a "complicated matter" and "It has not been updated since several months" (!) http://wiki.openstreetmap.org/wiki/Coastline http://wiki.openstreetmap.org/wiki/Coastline_error_checker So, you can delete a coastline without problems as long the way(s) you are deleting create a closed feature (like small island or lake). If you delete a larger coastline (to replace it by a Canvec natural=water polygon for example) you must make sure to join both undeleted coastline extremities to remove all gaps. Actually, for large water area, I find it easier to replace segments of the original coastline with corresponding geometry of the Canvec water feature... - Cut both coastline/Canvec water feature overlapped segments; - Delete the overlapped coastline segment; - Change the natural=water tag of the Canvec segment for natural=coastline; - Join both Canvec segment extremities to the original coastline; - Check for the direction of the coastline. The rule is "water on the right". Once every overlapped Coastline/Canvec water feature are replaced, remove unused Canvec segments. Use the Validator (including upload check option) to find problems in the coastline. Hope it helps Daniel -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of G. Michael Carter Sent: September 23, 2010 11:56 To: Nakor Cc: [email protected]; [email protected] Subject: Re: [Talk-ca] Missing islands and coastline The mix of natual=water and natural=coastline is because their dual objects. The natural=coastline is needed as the great lakes (as far as I know) is connected to the ocean. So deleting the coastline would delete portions of the Atlantic Ocean. What I'm doing is enclosing the Canadian side of the great lakes, (object http://www.openstreetmap.org/browse/relation/1120169 (which needs to be loaded in sections in JOSM) My reasons: 1. Coastline's need to be complete to render properly. So if your loading Toronto island (Lake Ontario) into a system, you have to pull half the worlds oceans to get it to render properly... as with incomplete data a rendering engine can't till which side contains the water. Having a enclosed relation allows you to pull just that area. 2. It's currently impossible to tell if a coastline object is fully enclosed inside JOSM editing. But if you have a enclosed relation object (with type natural=water) where just one side is the coastline. You can easily tell by downloading the relation (aka 1120169) 3. Naming. Can't name a sting of coastline as easy as a single relation. As for coastlines inland (like Lake Simcoe) make absolutely no sense to me as it's not a coastline. So my thought, if you have a natural=water object that more accurately represents the body of water... use it to replace the interior coastline. But that's just my take... On 22/09/10 12:46 PM, Nakor wrote: > Michael, > > The relation in question is > http://www.openstreetmap.org/browse/relation/1124369 but hit a wall > here. I cannot modify it (both Potlatch and JOSM time out). Isle > Royale (which was my initial concern) is still missing on a couple > zoom levels. > > Before I continue trying to fix this it seems there are a mix of > natural=water and natural=coastline for the Great Lakes. I'd like to > have this consistent over the Great Lakes but am not sure which one to > use. Please comment which one would be better/worse and why? > > Thanks, > > N. > > > > On 9/20/2010 10:20 AM, G. Michael Carter wrote: >> It was brought to my attention there was some problems in Lake >> Superior area, but the problems seem to be all over the great >> lakes. There's a user, who's name I don't have handy, creating >> massive relationship objects of the great lakes. I think this might >> be sinking a lot of the islands. The island objects were last >> modified by this user in the cases I checked. >> >> However, if you refresh the mapnik (aka /dirty) the tiles everything >> seems to be refreshing ok. Just wanted to let people know. If >> you find some area underwater refresh the tiles, before investigating. >> >> Michael >> >> >> >> _______________________________________________ >> Talk-ca mailing list >> [email protected] >> http://lists.openstreetmap.org/listinfo/talk-ca > > > _______________________________________________ > Talk-ca mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/talk-ca _______________________________________________ Talk-ca mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-ca _______________________________________________ Talk-ca mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-ca
