Extract data from a multipolygon.
I’m not a fan of multipolygons because they make post-processing much more difficult. Now I’m stuck with another one of these unnecessary things—a location that was mapped as an MP just because there’s a fountain on it.
So I want to break it up, but copying the data is really cumbersome.
Wasn’t there an add-on for JOSM? I seem to remember one, but I can’t find it.
Could you please mention the OSM object ID (and use the term “multipolygon” in the thread title)?
You seem to want to edit this multipolygon only to make it easy for your tool to consume the data.
If there’s really a problem with the tagging or mapping of the multipolygon, or because it’s out of place, then it should be fixed; but if you only want to delete the multipolygon just because it’s tricky for your tool to process it, that’s tagging for the render (or tagging for the data consumer in this case) and it should be avoided.
I’m certainly not a fan of multipolygons where there is an alternative, but that does seem like an entirely correct use of an MP.
What issues do you have with postprocessing, as long as you are not reinventing the wheel you should find good tool support fro MPs.
Landuse is used without any issues without an MP; no one would map a `landuse=grass` within a `landuse=residential` area as an MP either. So why is it done so often for a square or other features? That said, I’ve also seen quite often that someone has turned a `landuse=residential` into an MP just because there was a cemetery in it. But a cemetery belongs just as much to a residential area as a school, hospital, etc. You have to be able to generalize; otherwise, the map will eventually become unusable.
Please post the specific example in OSM you have in mind
Wanna bet? =) Judging by a quick database search, there are about 500 such instances in Sweden alone (which is what I have loaded into PostGIS).
(I’m not saying that this is the Right Way to map, just that there are more than zero persons doing it.)
I just came across another roundabout here—okay, that’s not really a big deal—one that’s mapped with landuse=grass and has a fountain (as a polygon) in the middle, so that it’s correctly classified as an MP, since there’s no grass in the fountain. You see things like that all the time. A square with a fountain or a kiosk that becomes an MP, and so on.
for place=square you won’t cut these out, but for area highway=pedestrian you would