[Tagging] editing polygons in JOSM

[Peter Wendorff]

Hi Tom

Cutting by a line is easy:
- add a way with nodes for start and end of the line where it cut's the
polygon first and last.
- add nodes where that new way intersects the old polygon
- split the new way at these nodes
- split the old polygon at these nodes
- delete the parts of the old polygon that is outside the new one
- combine polygon and some of the new ways (parts of the one you drawed
initially) where that should be done

If that creates holes, combine the resulting parts as a multipolygon if
necessary.

Clipping by a new polygon is basically the same - but draw that new
polygon first instead of the line, then proceed as described above.

As far as I know there is no automatic way to do one of these.

regards
Peter


Am 27.05.2014 20:23, schrieb Tom Gertin:
> I don't know if the tagging listserv is the appropriate forum for this
> questions, but I can't find a better one.
> 
> I want to try to complete several polygon editing operations using JOSM.
> Anybody know if this is possible or how to accomplish these tasks in JOSM
> or any other free editor?
> 
> 1. Clip a polygon using another polygon
> 2. Cut a polygon using a line
> 
> I already know how to create a hole in a polygon using a polygon and relate
> them, thus creating a multi-polygon.
> 
> Thanks!
> 
> Tom G.
> 
> 
> 
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