Hi Brendan, I've just looked at the piece of coastline in question and found two errors in it (both now fixed):
* There was a duplicate node * At a different place, the coastline overlapped itself. I can see how these (particularly the overlap) could be confusing to the DB. It may be worth trying it again with the new data. Dermot 2009/2/18 brendan barrett <[email protected]>: > Hi > > I've just signed up to the dev mailing list, and hopefully i'll catch > up by reading the archives. For now though I have a question and > please don't follow up with insults if you see the names Microsoft or > SQL Server :P > > I'm trying to render coastlines in an application that I am building. > The concept is simple: find the lines, and join them end on end until > you get an area. Now my problem is with OGC standards. I'm using Sql > Server 2008 *ducks for cover* and more specifically the new Sql Server > Spatial types (Geography and Geometry). Sql Server 2008 seems to be > pretty strict with OGC standards, and I am but a beginner when it > comes to OGC standards. > > The problem i'm having is with some coastlines in OSM that double back > on themselves. Like this one: > > This way http://www.openstreetmap.org/browse/way/13858554 doubles back > on itself with this node > http://www.openstreetmap.org/browse/node/130020792 having the same > latitude as this consecutive node > http://www.openstreetmap.org/browse/node/130020793. > > I think this is the reason for the way being invalid in Sql Server's > eyes. The MS folks have included the MakeValid() function which > "corrects" the way to comply with OGC standards, but this changes the > latitude and longitude of every point in the line ever so slightly, > and that's not desirable if you are matching ways end on end. I can > use the Node Ids to match them, but the bigger issue is that my data > is "invalid" and I can't use other spatial methods on it. > > I have 4 questions: > 1. Is this doubling back really an OGC restriction? It makes sense > that these ways don't double back because it doesn't serve any purpose > for a coastline (or for any line, you would expect even a path that > doubles back to be at least some distance apart, or simply labeled two > way). > 2. If this is a problem, is it something that will be fixed in the > editors / the API? > 3. Is there anyone else here with experience with SQL Server 2008 > Spatial and OSM that might have some tips on dealing with all these > ways? > 4. Does PostGIS have these types of issues? > > I'm thinking that the only way for me to deal with this is to correct > the data in OSM (if it's clearly incorrect) or in my database once > imported (if there's no other solution). > > Thoughts? > > _______________________________________________ > dev mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/dev > -- -------------------------------------- Iren sind menschlich _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
