On Tue, Mar 11, 2008 at 1:54 PM, James Ewen <[EMAIL PROTECTED]> wrote: > So, I've just started into my current obsession... mapping Strathcona > County, just east of Edmonton, Alberta, Canada. > > I'm running into problems trying to learn how to get things done. > > I want to define an area, that borders on another area. i.e. The > border between Strathcona County, and Elk Island National Park. These > two entities share a common border. I have defined Strathcona County > by drawing a way around the full extent of the county. I would assume > that you set the tag to boundary=civil or administrative for the > county, and boundary=national park for Elk Island. > > What do you do about the shared border? It can only belong to one or > the other entity. All borders should be shared between two entities. I > saw an entry about defining the left and right sides of a boundary, > but do not understand how to use it. Has anyone figured these things > out, and have an practical examples to look at? > > It seems to be very counter-intuitive to have to draw a common > boundary twice, once for each entity, especially if it is a very > convoluted boundary following for example a river. > > James > > _______________________________________________ > newbies mailing list > [email protected] > http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/newbies >
There are currently two commonly used border drawing methods: 1) Draw a complete closed polygon around the area, sharing nodes where they meet other borders. 2) Make a border up of separate ways so one way defines one border between two places, using a relation to group the pieces of a region's border together. Each method has its advantages and disadvantages, which an editor uses is generally up to their own personal style, there is no real overall preference for either yet. In your case, it might just be easiest to use the separate way method, since you note that some sections of the border are particularly complex. In that case, you'd split the way where an area on either side changes and tag appropriately. I may as well give an example as well. http://openstreetmap.org/?lat=51.3598&lon=-0.2241&zoom=15&layers=0BFT This area of London has quite a complex border. The border visible is between the districts of Epsom and Sutton and the counties of Surrey and Greater London respectively. The border runs down the edge of Nonsuch Park (west) and Cheam Park/Recreation Ground, and along Cheam Road to the south. The parks are all drawn as closed polygons, sharing the nodes at the edges where they join. The border is drawn as a single way with the tags: admin_level=6 left:county=Greater London left:district=Sutton boundary=administrative right:county=Surrey right:district=Epsom & Ewell The border in turn shares nodes with the parks and the road. I hope this helps and that I haven't confused too much. -- Regards, Thomas Wood (Edgemaster) _______________________________________________ newbies mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/newbies
