Bogus "Areas share segment" warning by validator

[mkoniecz]

Maybe there are cases where warning like this is useful but for now I encountered it only for buildings where it is correct tagging.

Example - entire old city of Kraków: ​http://www.openstreetmap.org/?mlat=50.061667&mlon=19.937222&zoom=15#map=16/50.0618/19.9371 (see ​https://en.wikipedia.org/wiki/File:Sukiennice_and_Main_Market_Square_Krakow_Poland.JPG and ​https://en.wikipedia.org/wiki/Main_Square,_Krak%C3%B3w)

Maybe after excluding building=* this rule will start reporting something useful.

[simon04]

If areas share a long segment, it might be better to introduce multipolygons. This is the idea of this informational message. Thus, I'd close this as invalid.

[Don-vip]

Mmmm in that case we're talking about adjacent buildings that share a segment, yes, but converting all of them to multipolygons doesn't bring much. This is a normal way of tagging buildings in urban areas, I agree it should not raise any message, even informational.

Why do we have this check to begin with ?

[simon04]

Right, we could exclude buildings. In my area, some large forest areas are split at artificial points to make the way polygon smaller in size. Instead, they share a long+complex segment (e.g. way/146342814 + way/146342845). This test identifies such cases.

[simon04]

We also could change this test to generate a warning only if a way segment consisting of at least 4 nodes is shared.

[Don-vip]

In France you can easily find buildings with small segments and more than 4 nodes. Think of buildings adjacent to churches for example, like here:
​http://www.openstreetmap.org/#map=19/43.60096/1.43959

[simon04]

In 6862/josm:

see #9598 - Validator: report "Overlapping ways" only if at least 3 segments are shared

[simon04]

Do we want a separate handing for buildings?

[Don-vip]

Replying to simon04:

Do we want a separate handing for buildings?

It is much better right now, but not still perfect in urban areas, there's still too much noise :) So yes I think we can ignore warnings when both areas are buildings.

[Don-vip]

Or maybe just when one of them is a building. There's plenty of areas drawn alongside a building (parkings, gardens, etc.). We could also ignore barriers (see #9695).

[simon04]

In 6870/josm:

fix #9598 - Validator: do not report "Overlapping ways" for buildings

[simon04]

A testcase

[mkoniecz]

Is it possible to mention "it might be better to introduce multipolygons" in message? It is not obvious, I wanted to again report this bug because I had no idea what should be fixed.

I know that it would mean additional work for translators.

[Don-vip]

Please don't reopen defects closed long ago to request something else. Please open a new enhancement for this, or simply update the online documentation for this warning.

[Don-vip]

See #16933 for building:part